Rewrite the README sentence by sentence (closes #157 )

The README is rewritten from scratch against the prose rules of #157: every sentence under about 30 words, lists as bullets, every technical term defined where it first appears, and every statement checked against the code on next. It leads with what RouteWatch is and how to run it, then the pages, the API and the blocklists, then the settings, memory and upaas, and last the design and the development workflow. The dated entry goes into TODO.md. Model: fable-5-1
Rewrite TODO.md sentence by sentence (part of #157 )
2026-11-03 00:10:08 +01:00 · 2026-11-02 23:44:09 +01:00 · 2026-11-02 23:10:09 +01:00 · 2026-11-02 08:00:00 +01:00 · 2026-11-02 03:59:47 +01:00 · 2026-11-02 03:27:10 +01:00
24 changed files with 2241 additions and 1065 deletions
@@ -10,151 +10,223 @@

 # Status

-pre-1.0. No git tags. `main` last took `next` on 2026-10-06, through
-https://git.eeqj.de/sneak/routewatch/pulls/6. The linter and the tests are
-phases of the Docker build, and the Gitea workflow runs `script/cibuild` (the
-format check of the Go code and the markdown, both phases, then the image) on
-every push. The image sets memory ceilings for a 5 GiB container (README
-"Memory") and the README says how to run it under upaas (README "Running under
-upaas"). A 25-hour run of `a9b6860` on the live feed peaked at about 0.6 GiB
-(https://git.eeqj.de/sneak/routewatch/issues/3). A run of `825afa2` on the live
-feed found the prefix handler dropping about a quarter of its updates because
-its route writes were slower than the feed
-(https://git.eeqj.de/sneak/routewatch/issues/96); the cheaper writes since then
-are measured by a benchmark, not yet on the live feed.
+RouteWatch is pre-1.0, with no git tags. `main` last took `next` on 2026-10-27,
+through https://git.eeqj.de/sneak/routewatch/pulls/166.
+https://git.eeqj.de/sneak/routewatch/pulls/202 carries the commits since then
+into `main`. It is labelled `merge-ready` and waits for sneak.
+
+The linter and the tests are phases of the Docker build. The Gitea workflow runs
+`script/cibuild` on every push. That script runs the two phases and checks the
+formatting of the Go code and the markdown. Then it builds the image.
+
+The image sets memory ceilings for a 5 GiB container (README "Memory"). README
+"Running under upaas" says how to run it.
+
+A five-day run of `1c65656` on the live feed, from 2026-10-27 to 2026-11-01,
+found three problems:
+
+- The prefix handler dropped updates while a peer's session went down
+  (https://git.eeqj.de/sneak/routewatch/issues/216).
+- The AS handler dropped updates when the feed burst
+  (https://git.eeqj.de/sneak/routewatch/issues/217).
+- The WHOIS fetcher kept asking a registry that had refused it
+  (https://git.eeqj.de/sneak/routewatch/issues/218).
+
+All three are fixed on `next`. So is
+https://git.eeqj.de/sneak/routewatch/issues/222, which the third fix brought up.
+A run of `26d939a` on the live feed showed the prefix handler still dropping
+updates while the home page's cards were worked out.
+https://git.eeqj.de/sneak/routewatch/issues/226 fixed that on `next`.
+https://git.eeqj.de/sneak/routewatch/issues/225, also on `next`, takes the peers
+whose sessions go down together out of the table in one walk. A 24-hour run of
+`9bd0e91` on the live feed is checking whether any handler still drops updates.
+
+Two questions wait for sneak: which history the prefix page keeps
+(https://git.eeqj.de/sneak/routewatch/issues/161), and which fields the IP
+lookup answer gains (https://git.eeqj.de/sneak/routewatch/issues/203).
+
+The order of the project's remaining work is kept on
+https://git.eeqj.de/sneak/routewatch/issues/86.

 # Next Step

-Run `next` on the live feed, as README "Running under upaas" describes, until
-the routing table stops growing. Post its size and memory figures on
-https://git.eeqj.de/sneak/routewatch/issues/122. The same run makes the final
-check https://git.eeqj.de/sneak/routewatch/issues/96 names: whether the prefix
-handler still drops updates after the first hour. If it does, a new issue
-follows with the numbers. Then an audit of the code at the commit that run
-tested.
+Post the outcome of the 24-hour run of `9bd0e91` on
+https://git.eeqj.de/sneak/routewatch/issues/226: whether any handler still drops
+updates, and the process's peak memory against 5 GiB. File an issue for each
+problem the run finds.

 # Completed Steps

+- 2026-11-02: `README.md` is rewritten from scratch, sentence by sentence,
+  against the rules of https://git.eeqj.de/sneak/routewatch/issues/157. Every
+  statement was checked against the code on `next` (closes #157)
+- 2026-11-02: `TODO.md` is rewritten from scratch, sentence by sentence, against
+  the rules of https://git.eeqj.de/sneak/routewatch/issues/157. Every Completed
+  Steps entry keeps its date, its facts and its issue. Status and Next Step
+  describe the repo as the tracker shows it (part of #157)
+- 2026-11-02: when the sessions of several peers go down, the prefix handler
+  takes the peers out of the routing table together. The table's `PeersDown`
+  takes several peers out of every prefix in one walk. One walk runs at a time.
+  The next one takes every peer whose session went down since the previous one
+  began. Each peer used to have a walk of its own. A peer's messages stayed held
+  back while the walks queued ahead of its own ran. The handler holds back at
+  most 150,000 messages, about 150 MiB. It used to hold back at most 20,000. The
+  status page shows how many messages the handler holds back (closes #225)
+- 2026-11-02: working out the home page's cards no longer stops the prefix
+  handler. The walk over the routing table holds the table's lock for 10,000
+  prefixes at a time, then lets the lock go for as long again, as `PeerDown`
+  does. It used to take the lock back at once. The prefix handler then applied
+  about one update per 10,000 prefixes walked. During a walk, its queue could
+  fill, and the streamer then dropped updates for it (closes #226)
+- 2026-11-02: A skipped WHOIS lookup now makes the fetcher wait longer before
+  the next one, as a failed lookup does. A lookup is skipped when its RIR is
+  paused. An RIR is one of the five regional Internet registries. The longest
+  wait is one minute. The status page does not count a skip as a failure. A skip
+  used to leave the wait as it was. Each lookup asks IANA which RIR holds the AS
+  before it finds that RIR paused. So while most stale ASes belonged to a paused
+  RIR, the fetcher could ask IANA every second (closes #222)
+- 2026-11-02: A peer's session going down no longer stops the prefix handler.
+  The handler runs the routing table's `PeerDown` on a goroutine of its own, one
+  peer at a time. Meanwhile it goes on taking messages. `PeerDown` holds the
+  table's lock for 10,000 prefixes at a time, then lets the lock go for as long
+  again. The handler holds back the down peer's later messages until that peer's
+  `PeerDown` returns. Then the handler applies them in order, one at a time, and
+  takes new messages in between. It holds back at most 20,000 messages. At that
+  number, `HandleMessage` waits until one of them is applied. When `Stop` runs
+  past its deadline, it logs how many held-back messages were not applied
+  (closes #216)
 - 2026-11-02: RouteWatch pauses an RIR's or NIC.br's WHOIS server for an hour
-  after the server refuses a query. A refused or reset connection is a refusal.
-  So is an answer with an `%ERROR:201:` or `%ERROR:202:` line. Lookups at the
-  other servers go on. An AS whose RIR is paused is looked up after the pause.
-  IANA is never paused, because a pause of IANA would stop every lookup. A
-  refusal by IANA is an ordinary failure. NIC.br is also paused for an hour
-  after it says RouteWatch has passed NIC.br's query limit. Before, the fetcher
-  asked a server again within seconds of a refusal (closes #218)
- 2026-10-27: the tests of `internal/routewatch` no longer fail on a loaded
+  after the server refuses a query. NIC.br is Brazil's registry. A refused or
+  reset connection is a refusal. So is an answer with an `%ERROR:201:` or
+  `%ERROR:202:` line. Lookups at the other servers go on. An AS whose RIR is
+  paused is looked up after the pause. While NIC.br is paused, a Brazilian AS
+  gets the details from LACNIC's answer. IANA is never paused, because a pause
+  of IANA would stop every lookup. A refusal by IANA is an ordinary failure.
+  NIC.br is also paused for an hour after it says RouteWatch has passed its
+  query limit. Before, the fetcher asked a server again within seconds of a
+  refusal (closes #218)
+- 2026-11-02: The AS handler never waits for a database write. Its batch holds
+  one entry per AS, with the earliest and the latest time of its updates. So the
+  batch no longer grows with the feed's rate. It used to hold one entry for each
+  AS of each path. At 300,000 entries it waited for the write in progress. In a
+  burst of the feed its queue then filled, and the streamer dropped messages for
+  it (closes #217)
+- 2026-10-27: The tests of `internal/routewatch` no longer fail on a loaded
  host. Five of them gave `HandleMessage` two seconds to apply a full prefix
-  batch, which under the race detector can take longer. A test now waits up to
-  15 seconds for each step it expects. The tests of the handlers' limits give
-  the handlers small ones, so the package no longer runs past its 90-second
+  batch. Under the race detector that can take longer. A test now waits up to 15
+  seconds for each step it expects. The tests of the handlers' limits now give
+  the handlers small limits. So the package no longer runs past its 90-second
  limit (closes #213, #215)
- 2026-10-27: the server works out the home page's cards every minute until it
-  stops. It used to work them out only once, at startup: the end of the context
-  that `Start` is given stopped the refreshes (closes #211)
- 2026-10-27: README "Rationale" says why RouteWatch exists: to answer our other
-  services' questions about IP addresses, from its own routing table and the
-  WHOIS details it keeps. It still says what RIS Live does not give (closes
-  #204)
- 2026-10-27: every JSON answer carries `@meta`. A panic on a JSON route answers
+- 2026-10-27: The server works out the home page's cards every minute until it
+  stops. It used to work them out only once, at startup. The end of the context
+  given to `Start` stopped the refreshes (closes #211)
+- 2026-10-27: README "Rationale" says why RouteWatch exists. RouteWatch answers
+  our other services' questions about IP addresses, from its own routing table
+  and the WHOIS details it keeps. The section still says what RIS Live does not
+  give (closes #204)
+- 2026-10-27: Every JSON answer carries `@meta`. A panic on a JSON route answers
  500 with the JSON error body. `/status.json` and the health check answer 405
  with the JSON error body to any method they do not take. The 500 and the 405
  used to have an empty body. The home page's IP lookup shows the whole JSON
  answer, `@meta` included. It used to show only the answer's `data`, or only
  the message of an error answer. A test checks `@meta` on every JSON route, in
  its successes and its errors (closes #201)
- 2026-10-27: every value in a JSON answer that has a unit is a number, with the
-  unit at the end of its field name. `@meta.execution_time` is now
-  `execution_time_ms`. The stats' `uptime`, `connection_duration` and
-  `memory_usage` are now `uptime_seconds`, `connection_duration_seconds` and
-  `memory_usage_bytes`. `whois_stats.current_interval` is now
-  `current_interval_seconds`. They used to be strings such as "12 ms",
-  "1h18m34s" or "1.1 GB". `connection_duration_seconds` is null while the feed
-  is not connected. `API_POLICIES.md` is vendored from `sneak/prompts`, and
-  `REPO_POLICIES.md` re-vendored (closes #199)
- 2026-10-27: every result of the IP lookup has the same fields. A field without
-  a value is null. It used to be left out. An address with no live route has
-  every route and AS field set to null, and `ptr` is an empty list when there
-  are no PTR names. New fields give the number of origin ASes of the netblock,
-  in `num_origins`, and which they are, in `origin_asns` (closes #200)
- 2026-10-27: with `TRUSTED_PROXIES` unset, the server trusts reverse proxies at
+- 2026-10-27: Every value with a unit in a JSON answer is a number. The unit is
+  at the end of the field name. `@meta.execution_time` is now
+  `execution_time_ms`. In the stats, `uptime` is now `uptime_seconds`,
+  `connection_duration` is now `connection_duration_seconds`, and `memory_usage`
+  is now `memory_usage_bytes`. `whois_stats.current_interval` is now
+  `whois_stats.current_interval_seconds`. They used to be strings such as "12
+  ms", "1h18m34s" or "1.1 GB". `connection_duration_seconds` is null while the
+  feed is not connected. `API_POLICIES.md` is vendored from `sneak/prompts`, and
+  `REPO_POLICIES.md` is re-vendored (closes #199)
+- 2026-10-27: Every result of the IP lookup has the same fields. A field without
+  a value is null. It used to be left out. An address with no route in the
+  routing table has every route and AS field set to null. `ptr` is an empty list
+  when there are no PTR names. The new field `num_origins` gives the number of
+  origin ASes of the netblock, and `origin_asns` gives which they are (closes
+  #200)
+- 2026-10-27: With `TRUSTED_PROXIES` unset, the server trusts reverse proxies at
  the private addresses of RFC 1918. `/ip/`, the home page's `curl` card and the
  request log then give the client's address from `X-Forwarded-For`. They used
-  to give the proxy's address. A list in `TRUSTED_PROXIES` replaces the default,
-  and `TRUSTED_PROXIES` set but empty trusts no proxy (closes #198)
- 2026-10-27: the home page has cards with figures of the routing table: the
-  newest and oldest kept route, the newest and oldest updated AS, the AS with
-  the most prefixes, the ASes with a single prefix, and fifteen well-known
-  networks. Two cards count the bogon announcements and the prefixes with more
-  than one origin AS, and link to the new pages `/bogons` and
-  `/multiple-origins` that list them. A new package, `internal/bogon`, tells
-  which prefixes and AS numbers are reserved. The server works the figures out
-  once a minute (closes #154)
- 2026-10-27: the per-peer route tables are gone, with the code that wrote,
+  to give the proxy's address. A list in `TRUSTED_PROXIES` replaces the default.
+  `TRUSTED_PROXIES` set but empty trusts no proxy (closes #198)
+- 2026-10-27: The home page has cards with figures of the routing table. One
+  card shows the newest and the oldest kept route. One shows the newest and the
+  oldest updated AS. One shows the AS with the most prefixes. One shows the ASes
+  with a single prefix. One shows fifteen well-known networks. Two cards count
+  the bogon announcements and the prefixes with more than one origin AS. They
+  link to the new pages `/bogons` and `/multiple-origins`, which list them. A
+  new package, `internal/bogon`, tells which prefixes and AS numbers are
+  reserved. The server works the figures out once a minute (closes #154)
+- 2026-10-27: The per-peer route tables are gone, with the code that wrote,
  counted and read them. The prefix handler applies each update to the routing
-  table in memory and writes the table's changes every second. It also stores
-  each new prefix with its first-seen time. The image's memory limits are set
-  for a full routing table of about 1 GB: `GOMEMLIMIT` is 2.5 GiB, the writing
-  connection's page cache 512 MiB, and SQLite's heap limits 768 MiB and 1 GiB
-  (closes #122)
- 2026-10-27: the pages, the API and the stats read every route from the routing
+  table in memory. It writes the table's changes every second. It also stores
+  each new prefix with its first-seen time. The image's memory limits fit a full
+  routing table of about 1 GB. `GOMEMLIMIT` is 2.5 GiB. The writing connection's
+  page cache is 512 MiB. SQLite's soft and hard heap limits are 768 MiB and 1
+  GiB (closes #122)
+- 2026-10-27: The pages, the API and the stats read every route from the routing
  table in memory. For a prefix with several origin ASes, the IP lookup gives
  the one most peers carry. Its `last_seen` is the newest kept route's time. The
-  prefix page and API list every peer that carries the prefix, with an AS path,
-  next hop and time only for the kept routes. The stats count the origins whose
-  kept routes were all withdrawn, in `origins_without_kept_route` (part of #122)
- 2026-10-27: the prefix, AS and peer handlers make a timed write on every tick
-  of their timers, every 1, 2 and 2 seconds. They used to skip every other tick.
-  A full batch's write restarts the timer, so the next timed write comes one
-  interval after that write began (closes #192)
- 2026-10-27: once the stop deadline has passed, the AS, peer and peering
-  handlers start no write either. A full batch or a tick of the timer that
-  waited while a write ran past the deadline could still start one. The flush
-  goroutines of the prefix, AS and peer handlers now run the same code (closes
-  #189)
- 2026-10-27: once the stop deadline has passed, the prefix handler starts no
-  flush. A batch that filled while a write ran past the deadline could still be
-  written after it (closes #188)
- 2026-10-27: the prefix handler applies each update to the routing table in
-  memory, and writes the table's changes to the database every second. A write
-  takes at most 20,000 changed pairs, and the rest follow in the next writes. A
-  failed write is written again later. Startup reads the table before the
-  streamer connects. The pages still read the per-peer route tables (part of
+  prefix page and API list every peer that carries the prefix. Only the kept
+  routes show an AS path, a next hop and a time. The stats count the origins
+  whose kept routes were all withdrawn, in `origins_without_kept_route` (part of
  #122)
- 2026-10-27: the database keeps a copy of the whole routing table in a new
+- 2026-10-27: The prefix, AS and peer handlers make a timed write on every tick
+  of their timers. The prefix handler's timer ticks every second. The other two
+  tick every two seconds. They used to skip every other tick. A full batch's
+  write restarts the timer. So the next timed write comes one interval after
+  that write began (closes #192)
+- 2026-10-27: Once the stop deadline has passed, the AS, peer and peering
+  handlers start no write either. Before, a full batch or a timer tick could
+  wait while a write ran past the deadline. Either could then start one more
+  write. The flush goroutines of the prefix, AS and peer handlers now run the
+  same code (closes #189)
+- 2026-10-27: Once the stop deadline has passed, the prefix handler starts no
+  flush. Before, a batch that filled during a late write could still be written
+  after the deadline (closes #188)
+- 2026-10-27: The prefix handler applies each update to the routing table in
+  memory. It writes the table's changes to the database every second. A write
+  takes at most 20,000 changed pairs of prefix and origin AS. The rest follow in
+  the next writes. A failed write is written again later. Startup reads the
+  table before the streamer connects. The pages still read the per-peer route
+  tables (part of #122)
+- 2026-10-27: The database keeps a copy of the whole routing table in a new
  `routes` table, one row per prefix and origin AS. The peers' numbers are in a
-  new `route_peers` table. One function writes the pairs that changed in memory,
-  and another reads the whole table back into memory at startup. Nothing uses
-  them yet (part of #122)
- 2026-10-27: a new package, `internal/routetable`, holds the whole routing
+  new `route_peers` table. One function writes the pairs that changed in memory.
+  Another reads the whole table back into memory at startup. Nothing uses them
+  yet (part of #122)
+- 2026-10-27: A new package, `internal/routetable`, holds the whole routing
  table in memory. For each prefix and origin AS it keeps the peers that carry
-  it, one bit per peer, and the two newest of their routes. Nothing uses it yet
-  (part of #122)
- 2026-10-27: each result of the IP lookup lists the public blocklists the
+  it, one bit per peer. It also keeps the two newest of their routes. Nothing
+  uses it yet (part of #122)
+- 2026-10-27: Each result of the IP lookup lists the public blocklists the
  address is on, in `blocklists`. The lists are DShield, Feodo Tracker, two
-  FireHOL lists, Spamhaus DROP and the Tor exit list. RouteWatch downloads each
-  list on its own schedule and answers from copies in memory. The copies are
-  also kept in the state directory's `blocklists` directory. IP lookup answers
-  carry `Cache-Control`. An address with no live route now has a result too,
-  without route fields, so the IP lookup no longer answers 404 (closes #158)
- 2026-10-27: the home page has an IP information API card. It shows the `curl`
-  command that looks up the visitor's own address at `/ip/{addr}`, and that
-  command's live answer (closes #156)
- 2026-10-27: on the AS page, a click on the heading of the IPv4 or the IPv6
+  FireHOL lists, two Spamhaus DROP lists and the Tor exit list. RouteWatch
+  downloads each list on its own schedule and answers from copies in memory. The
+  copies are also kept in the state directory's `blocklists` directory. IP
+  lookup answers carry `Cache-Control`. An address with no route now has a
+  result too, without route fields. So the IP lookup no longer answers 404
+  (closes #158)
+- 2026-10-27: The home page has an IP information API card. It shows the `curl`
+  command that looks up the visitor's own address at `/ip/{addr}`. It also shows
+  that command's live answer (closes #156)
+- 2026-10-27: On the AS page, a click on the heading of the IPv4 or the IPv6
  prefix list folds or unfolds the list. Both lists start open (closes #155)
- 2026-10-27: the AS page lists its IPv4 and its IPv6 prefixes by mask length,
-  shortest first, and prefixes of one mask length by address. They used to be
-  listed by address (closes #153)
- 2026-10-27: on `/` and `/status`, a spinner beside the status turns one frame
-  each time the stats show more messages than the time before. A page that has
-  not seen more messages for three refreshes shows "stale" and the time since
-  then instead, in red (closes #152)
- 2026-10-27: the WHOIS details of a Brazilian AS keep their accented letters.
-  LACNIC's answer for such an AS comes from NIC.br, Brazil's registry, with each
-  accented letter replaced. The details now come from NIC.br's own server,
-  `whois.registro.br`. When that query fails, the details from LACNIC's answer
-  are kept and a warning is logged. After NIC.br answers that RouteWatch is over
-  its query limit, RouteWatch stops asking NIC.br for an hour (closes #174)
+- 2026-10-27: The AS page lists its IPv4 and its IPv6 prefixes by mask length,
+  shortest first. Prefixes of one mask length are listed by address. They used
+  to be sorted by address first, then by mask length (closes #153)
+- 2026-10-27: The connection status on `/` and `/status` gets a spinner. It
+  turns one frame each time the stats show more messages than the time before.
+  After three refreshes with no new messages, the page shows "stale" in red
+  instead. Next to it is the time since the last fresh answer (closes #152)
+- 2026-10-27: The WHOIS details of a Brazilian AS keep their accented letters.
+  LACNIC's answer for such an AS is NIC.br's answer with each accented letter
+  replaced. NIC.br is Brazil's registry. The details now come from NIC.br's own
+  server, `whois.registro.br`. When that query fails, the details from LACNIC's
+  answer are kept and a warning is logged. RouteWatch stops asking NIC.br for an
+  hour after NIC.br says RouteWatch is over its query limit (closes #174)
 - 2026-10-27: `make asupdate` stops with an error when the download of `as.csv`
  breaks off. The generator used to retry the failed read forever. A record that
  does not parse is still logged and skipped (closes #177)
@@ -163,182 +235,192 @@ tested.
  one AS. A failed download used to replace the list with an empty file. The
  generator reads `as.csv` from `ipverse/as-metadata`, the source's new name
  (closes #173)
- 2026-10-27: the WHOIS details of an AS at RIPE, APNIC or AFRINIC come only
+- 2026-10-27: The WHOIS details of an AS at RIPE, APNIC or AFRINIC come only
  from its `aut-num` object and the organisation object it names. RIPE and APNIC
  start their answer with the `as-block` object of the AS's block. Its dates
  were stored as the AS's (closes #168)
 - 2026-10-27: AS names keep their accented letters. The AS list built into
  RouteWatch is rebuilt from today's `as.csv`, which added a country code
  column. That file no longer lists AS 0 or the documentation AS numbers. A
-  WHOIS answer that is not valid UTF-8 is decoded as Latin-1, which RIPE and
-  APNIC send, before it is parsed and stored (closes #165)
- 2026-10-27: the Age column on the AS and prefix pages reads in words, such as
-  "5 minutes ago" or "2 weeks ago", instead of Go durations such as "360h0m0s
-  ago". An age under a minute reads in seconds, and one over a month in months
-  or years instead of a date (closes #163)
- 2026-10-26: a write to a stored AS, peering or peer keeps the earlier of the
-  two first-seen times and the later of the two last-seen times. An old update
-  from a collector catching up on a backlog no longer moves last seen back
-  (closes #162)
- 2026-10-26: the status page shows "Route Churn/min", the number of prefix
-  announcements and withdrawals, from all peers, in the last full clock minute.
-  `/api/v1/stats` reports it as `route_churn_per_min` in `stream`, which
+  WHOIS answer that is not valid UTF-8 is decoded as Latin-1 before it is parsed
+  and stored. RIPE and APNIC send Latin-1 (closes #165)
+- 2026-10-27: The Age column on the AS and prefix pages reads in words, such as
+  "5 minutes ago" or "2 weeks ago". It used to print Go durations such as
+  "360h0m0s ago". An age under a minute reads "now" or in seconds. An age over a
+  month reads in months or years instead of a date (closes #163)
+- 2026-10-26: A write to a stored AS, peering or peer keeps the earlier of the
+  two first-seen times. It keeps the later of the two last-seen times. An old
+  update from a collector catching up on a backlog no longer moves last seen
+  back (closes #162)
+- 2026-10-26: The status page shows "Route Churn/min". That is the number of
+  prefix announcements and withdrawals from all peers in the last full clock
+  minute. `/api/v1/stats` reports it as `route_churn_per_min` in `stream`. It
  replaces the moving average `route_churn_per_sec`. The messages and updates
  per second on `/` and `/status` are whole numbers (closes #160)
- 2026-10-26: the WHOIS fetcher backs off more slowly. A failure makes its wait
+- 2026-10-26: The WHOIS fetcher backs off more slowly. A failure makes its wait
  1.5 times as long, up to one minute instead of five. Its queries to RIPE,
-  APNIC and AFRINIC leave out person and role objects, which RIPE counts against
-  a daily limit per address. A refused query is logged with the RIR's error line
-  (closes #159)
- 2026-10-26: the home page's AS name search lists the ASes whose handle or
-  description holds the text, as links to their pages, from the new
-  `/api/v1/search/as`; the search ignores case. When the database has no record
-  of an AS, its page takes the handle and description from the AS list built
-  into RouteWatch and still lists the AS's prefixes (closes #151)
- 2026-10-19: README "HTTP Endpoints" lists every route with what it answers,
-  "Database Schema" matches `schema.sql`, and the rest of the README matches the
-  code; this file brought up to date (closes #72)
- 2026-10-19: route writes are cheaper: the live route and prefix tables lose
-  their random UUID keys and the prefix tables their duplicate index, a route
-  update sets only the columns that change, and every write goes through one
+  APNIC and AFRINIC leave out person and role objects. RIPE counts those objects
+  against a daily limit per address. A refused query is logged with the RIR's
+  error line (closes #159)
+- 2026-10-26: The home page's AS name search works. It lists the ASes whose
+  handle or description holds the text, as links to their pages. The new
+  `/api/v1/search/as` answers it. The search ignores case. When the database has
+  no record of an AS, its page takes the handle and description from the AS list
+  built into RouteWatch. It still lists the AS's prefixes (closes #151)
+- 2026-10-19: README "HTTP Endpoints" lists every route with what it answers.
+  README "Database Schema" matches `schema.sql`. The rest of the README matches
+  the code. This file is brought up to date (closes #72)
+- 2026-10-19: Route writes are cheaper. The live route and prefix tables lose
+  their random UUID keys. The prefix tables lose their duplicate index. A route
+  update sets only the columns that change. Every write goes through one
  connection with a page cache of 1 GiB (README "Memory"). A benchmark writes
  the prefix handler's largest batch faster than the feed sends it (closes #96)
- 2026-10-19: the WAL checkpoint, the incremental vacuum and ANALYZE take the
-  database lock every batch write holds, so a vacuum no longer fails with
-  "database is locked" and an ANALYZE no longer makes a batch write lose its
-  updates; ANALYZE runs as `PRAGMA optimize` with an analysis limit (closes #94)
- 2026-10-19: shutdown stops the streamer first, and each handler writes
-  everything left on its queue before it stops, so the updates waiting there are
+- 2026-10-19: The checkpoint of the WAL (SQLite's write-ahead log), the
+  incremental vacuum and `ANALYZE` take the database lock that every batch write
+  holds. So a vacuum no longer fails with "database is locked". An `ANALYZE` no
+  longer makes a batch write lose its updates. `ANALYZE` runs as
+  `PRAGMA optimize` with an analysis limit (closes #94)
+- 2026-10-19: Shutdown stops the streamer first. Each handler then writes
+  everything left on its queue before it stops. So the updates waiting there are
  no longer lost (closes #69)
- 2026-10-19: a path that ends in an AS set of several members has origin AS 0,
-  no known origin, instead of the set's last member, and the set adds no
-  peerings; the pages show such a route as having no known origin (closes #75)
+- 2026-10-19: A path that ends in an AS set of several members has origin AS 0,
+  which means no known origin. It used to have the set's last member as its
+  origin. The set adds no peerings. The pages show such a route as having no
+  known origin (closes #75)
 - 2026-10-19: `bgp_peer_count` drops to 0 when the last peer goes down (closes
  #92)
- 2026-10-19: `bgp_peer_count` counts every peer the feed has heard from, not
-  only those whose session opened since startup, and drops a peer whose session
-  goes down (closes #74)
- 2026-10-19: the shared files are re-vendored from `sneak/prompts` at
-  `0653579`: golangci-lint v2.14.0 and its configuration, lint and test as
-  `Dockerfile` phases that keep Go's and golangci-lint's caches, markdown
-  formatted with prettier, agent guidance in `AGENTS.md`; the code is fixed for
-  what the new linter configuration finds (closes #52)
- 2026-10-19: the streamer reads feed lines up to 1 MiB, so a line over 64 KiB
-  no longer ends the connection (closes #76)
- 2026-10-19: a peer's live routes are removed when its BGP session goes down;
-  `STATE` messages are never dropped for backpressure, and one that finds its
+- 2026-10-19: `bgp_peer_count` counts every peer the feed has heard from. It
+  used to count only the peers whose session opened since startup. It drops a
+  peer whose session goes down (closes #74)
+- 2026-10-19: The shared files are re-vendored from `sneak/prompts` at
+  `0653579`. The linter is `golangci-lint` v2.14.0 with its configuration. Lint
+  and test are `Dockerfile` phases that keep Go's and `golangci-lint`'s caches.
+  `make fmt` also formats the markdown with `prettier`. The agent guidance moves
+  to `AGENTS.md`. The code is fixed for what the new linter configuration finds
+  (closes #52)
+- 2026-10-19: The streamer reads feed lines up to 1 MiB. A line over 64 KiB used
+  to end the connection (closes #76)
+- 2026-10-19: A peer's live routes are removed when its BGP session goes down.
+  `STATE` messages are never dropped when a queue is full. One that finds its
  queue full waits for room ahead of the handler's other messages (closes #56)
- 2026-10-19: the prefix-length pages pick their sample with a bounded number of
-  index lookups instead of reading every route of that length, and list each
+- 2026-10-19: The prefix-length pages pick their sample with a bounded number of
+  index lookups. They used to read every route of that length. They list each
  prefix once (closes #66)
- 2026-10-19: a request past its time limit answers 504 instead of 408, and
+- 2026-10-19: A request past its time limit answers 504 instead of 408.
  `/api/v1/stats` answers 504 instead of 500 when its read runs out of time
  (closes #70)
- 2026-10-19: the AS, peer and prefix handlers write each batch outside the lock
-  their message handling needs, so messages keep coming off their queues during
-  a write; meanwhile the next batch grows to at most ten batch sizes (closes
+- 2026-10-19: The AS, peer and prefix handlers write each batch outside the lock
+  their message handling needs. So messages keep coming off their queues during
+  a write. Meanwhile the next batch grows to at most ten batch sizes (closes
  #65)
- 2026-10-19: a live route is identified by prefix and peer, so an announcement
-  with a new origin AS replaces the peer's route and a withdrawal removes it
+- 2026-10-19: A live route is identified by prefix and peer. So an announcement
+  with a new origin AS replaces the peer's route. A withdrawal removes it
  whatever its origin AS (closes #55)
- 2026-10-14: the streamer reconnects when RIS Live ends the stream or sends
-  nothing for 60 seconds, and the health check reports the feed disconnected
+- 2026-10-14: The streamer reconnects when RIS Live ends the stream or sends
+  nothing for 60 seconds. The health check reports the feed disconnected
  meanwhile (closes #53)
- 2026-10-14: the prefix page takes the names of the origin ASes from the prefix
-  query instead of reading every route of each origin AS (closes #67)
- 2026-10-14: the daemon exits with status 1 when its web server cannot listen
-  on its port, instead of running on without it (closes #73)
- 2026-10-14: the prefix pages parse the prefix before looking it up: one that
-  does not parse answers 400, and any valid way of writing a prefix finds its
-  routes (closes #71)
- 2026-10-14: the IP lookup ignores routes shorter than /8 for IPv4 and /16 for
-  IPv6, so a default route is no longer named as an address's owner (closes #57)
- 2026-10-14: a prefix batch keeps each peer's last update for a prefix, instead
-  of one update per prefix across all peers (closes #54)
+- 2026-10-14: The prefix page takes the names of the origin ASes from the prefix
+  query. It used to read every route of each origin AS (closes #67)
+- 2026-10-14: The daemon exits with status 1 when its web server cannot listen
+  on its port. It used to run on without a web server (closes #73)
+- 2026-10-14: The prefix pages parse the prefix before looking it up. One that
+  does not parse answers 400. Any valid way of writing a prefix finds its routes
+  (closes #71)
+- 2026-10-14: The IP lookup ignores routes shorter than /8 for IPv4 and /16 for
+  IPv6. So a default route is no longer named as an address's owner (closes #57)
+- 2026-10-14: A prefix batch keeps each peer's last update for a prefix. It used
+  to keep one update per prefix across all peers (closes #54)
 - 2026-10-14: `reconnect_count` in `/api/v1/stats` counts every reconnect
  (closes #68)
- 2026-10-03: `/api/v1/stats` serves the prefix distribution from memory, seeded
-  at startup and adjusted on every live-route write, so a request no longer
-  reads every live route (closes #30)
- 2026-10-03: a new database is created with `auto_vacuum` set to incremental,
-  through the connection string so it is set before the file is first written,
-  and each periodic incremental vacuum now returns up to 1000 free pages; the
-  late `PRAGMA auto_vacuum` in `Initialize`, which SQLite ignored, is gone
-  (closes #43)
- 2026-10-03: looking up an IP address no longer reads every IPv6 route: both
+- 2026-10-03: `/api/v1/stats` serves the prefix distribution from memory. The
+  distribution is seeded at startup and adjusted on every live-route write. So a
+  request no longer reads every live route (closes #30)
+- 2026-10-03: A new database is created with `auto_vacuum` set to incremental.
+  The setting goes in the connection string, so it is set before the file is
+  first written. Each periodic incremental vacuum now returns up to 1000 free
+  pages. The late `PRAGMA auto_vacuum` in `Initialize`, which SQLite ignored, is
+  gone (closes #43)
+- 2026-10-03: Looking up an IP address no longer reads every IPv6 route. Both
  families find the most specific live route with at most 33 or 129 lookups on
-  the prefix index, and the IPv4 range columns are gone. Prefixes from the feed
-  are stored in one text form, so an IPv6 withdrawal, which the feed sends
+  the prefix index. The IPv4 range columns are gone. Prefixes from the feed are
+  stored in one text form. So an IPv6 withdrawal, which the feed sends
  uncompressed, now removes its route (closes #48)
- 2026-10-02: a plain `docker build .` stamps the commit's tag or short commit
-  (`git describe --tags --always`) into the page footer instead of `unknown`:
-  `.dockerignore` sends `.git` without `.git/config`, a `VERSION` build argument
-  takes precedence, and `make build` stamps the same value (closes #46)
- 2026-09-29: the entrypoint creates the data directory if it is missing and
-  stops the start if a step fails; README "Running under upaas" no longer asks
+- 2026-10-02: A plain `docker build .` stamps the commit's tag or short commit
+  into the page footer. It used to stamp `unknown`. The value comes from
+  `git describe --tags --always`. `.dockerignore` sends `.git` without
+  `.git/config`. A `VERSION` build argument takes precedence. `make build`
+  stamps the same value (closes #46)
+- 2026-09-29: The entrypoint creates the data directory if it is missing. It
+  stops the start if a step fails. README "Running under upaas" no longer asks
  for the host directory to be created first (closes #42)
 - 2026-09-29: `.dockerignore` keeps `.git`, local build output, local databases
-  and `.env` out of the Docker build context, and so out of the source archive
-  in the image (closes #39)
- 2026-09-29: README first line names the MIT license and the author; the
-  License section now says MIT and links `LICENSE`, and an Author section was
-  added; this file brought up to date (closes #38)
- 2026-09-29: MIT `LICENSE` (closes #1)
- 2026-09-28: stopping the daemon while the feed is flowing no longer panics
-  with "send on closed channel": the read loop checks for a stop just before
-  handing a message to the handler queues, and a second `Stop` no longer closes
-  the queues again (closes #34)
+  and `.env` out of the Docker build context. So they stay out of the source
+  archive in the image (closes #39)
+- 2026-09-29: The README's first line names the MIT licence and the author. The
+  License section says MIT and links `LICENSE`. An Author section is added. This
+  file is brought up to date (closes #38)
+- 2026-09-29: `LICENSE` is added, with the MIT licence (closes #1)
+- 2026-09-28: Stopping the daemon while the feed is flowing no longer panics
+  with "send on closed channel". The read loop checks for a stop just before
+  handing a message to the handler queues. A second `Stop` no longer closes the
+  queues again (closes #34)
 - 2026-09-28: `docker stop` no longer kills the daemon 2 seconds after the stop
-  signal: the entrypoint switches to the `routewatch` user with `setpriv`
-  instead of `runuser`, so the daemon receives the signal itself and gets the
+  signal. The entrypoint switches to the `routewatch` user with `setpriv`
+  instead of `runuser`. So the daemon receives the signal itself. It gets the
  whole wait `docker stop` allows, up to its own 60-second limit (closes #33)
- 2026-09-28: ready to run under upaas: a set but invalid `PORT`,
-  `XDG_DATA_HOME` or `MALLOC_ARENA_MAX` stops the start, the health check
-  follows `PORT`, README "Running under upaas" section (closes #31)
- 2026-09-22: realtime in-memory database statistics: counts seeded at startup
-  and adjusted on every write, oldest/newest route timestamps via index-end
-  lookups; `/api/v1/stats` no longer scans the tables (closes #27)
- 2026-09-21: batch writes take the write lock when their transaction begins
-  (`_txlock=immediate`), so they wait out a WAL checkpoint instead of failing
+- 2026-09-28: RouteWatch is ready to run under upaas. A set but invalid `PORT`,
+  `XDG_DATA_HOME` or `MALLOC_ARENA_MAX` stops the start. The health check
+  follows `PORT`. README gains a "Running under upaas" section (closes #31)
+- 2026-09-22: The database statistics are kept in memory. The counts are seeded
+  at startup and adjusted on every write. The oldest and newest route times come
+  from a lookup at each end of an index. `/api/v1/stats` no longer scans the
+  tables (closes #27)
+- 2026-09-21: Batch writes take the write lock when their transaction begins
+  (`_txlock=immediate`). So they wait out a WAL checkpoint instead of failing
  with "database is locked" (closes #25)
- 2026-09-21: `MALLOC_ARENA_MAX=2` in the image caps glibc malloc arenas, so
-  memory outside the Go runtime no longer grows with the core count (closes #23)
- 2026-09-21: `GOMEMLIMIT=1536MiB` in the image; README Memory section with the
+- 2026-09-21: `MALLOC_ARENA_MAX=2` in the image caps the number of glibc malloc
+  arenas. So memory outside the Go runtime no longer grows with the core count
+  (closes #23)
+- 2026-09-21: The image sets `GOMEMLIMIT=1536MiB`. README "Memory" gives the
  memory budget and the 5 GiB container limit (closes #13)
- 2026-09-21: the four handler queues hold at most 20,000 messages each, down
+- 2026-09-21: The four handler queues hold at most 20,000 messages each, down
  from 100,000 (closes #11)
- 2026-09-21: two goroutine leaks fixed: the stats handlers after a timeout and
-  the streamer's tickers on every reconnect (closes #12)
- 2026-09-21: parsed RIS messages no longer keep the unused `Community` and
+- 2026-09-21: Two goroutine leaks are fixed. The stats handlers leaked after a
+  timeout. The streamer's tickers leaked on every reconnect (closes #12)
+- 2026-09-21: Parsed RIS messages no longer keep the unused `Community` and
  `Raw` fields (closes #9)
- 2026-09-21: `.editorconfig`, and a Gitea workflow that runs `script/cibuild`
+- 2026-09-21: `.editorconfig` is added. A Gitea workflow runs `script/cibuild`
  on every push (closes #14)
- 2026-09-21: the peering handler's AS-path map holds at most 500,000 paths and
-  is swapped for an empty one every 30 seconds instead of copied (closes #10)
- 2026-09-21: SQLite memory bounded across the whole connection pool: a 64 MiB
-  page cache on each connection, 1 GiB soft and 1.5 GiB hard heap limits (closes
-  #8)
- 2026-09-21: the Docker build runs the format check, the linter and the tests,
-  linting in a separate stage on a golangci-lint image pinned by digest (closes
-  #5)
- 2026-09-21: `make test` skips the live-network feed test (`-short`), so
+- 2026-09-21: The peering handler's AS-path map holds at most 500,000 paths.
+  Every 30 seconds it is swapped for an empty one instead of copied (closes #10)
+- 2026-09-21: SQLite's memory is bounded across the whole connection pool. Each
+  connection has a 64 MiB page cache. The heap limits are 1 GiB soft and 1.5 GiB
+  hard (closes #8)
+- 2026-09-21: The Docker build runs the format check, the linter and the tests.
+  Linting runs in a separate stage on a `golangci-lint` image pinned by digest
+  (closes #5)
+- 2026-09-21: `make test` skips the live feed test, with `-short`. So
  `make check` no longer depends on the network (closes #2)
- 2026-07-07 Adopted scripts-to-rule-them-all: `script/` entrypoints, Makefile
-  shims, README Entrypoints section
- 2026-02-22: repo policy compliance: required policy files, .gitignore update,
-  Makefile fmt-check/check/docker/hooks targets, gofmt pass
-  (repo-policies-compliance, unmerged)
- 2026-01-01: WAL checkpointing: periodic (5s), on startup with logging,
-  TRUNCATE mode; fixed slow queries
- 2025-12-31: status page: navbar, home page with search, oldest/newest route
-  timestamps, NULL handling in WHOIS stats; container runs as routewatch user
-  with proper state dir
- 2025-12-30: structured HTTP request logging, increased timeouts, CIDR prefix
-  URL routing fixes, status page metrics and footer
- 2025-12-29: Dockerfile multi-stage build with source archive; SQLite
-  incremental vacuum for non-blocking space reclamation
- 2025-07-27: initial RouteWatch BGP stream monitor
+- 2026-07-07: The scripts-to-rule-them-all layout is adopted. `script/` holds
+  the entrypoints. The `Makefile` targets `check`, `test`, `lint`, `fmt` and
+  `fmt-check` call them. So do `bootstrap`, `setup`, `docker` and `hooks`.
+  README gains an "Entrypoints" section
+- 2026-02-22: The repo is brought in line with the repo policies. The required
+  policy files are added. `.gitignore` is updated. The `Makefile` gains
+  `fmt-check`, `check`, `docker` and `hooks` targets. The Go code is formatted
+  with `gofmt`. The work was on the branch `repo-policies-compliance`, unmerged
+  when this entry was written
+- 2026-01-01: The WAL is checkpointed every 5 seconds, and at startup with a log
+  line. Checkpoints run in `TRUNCATE` mode. This fixed slow queries
+- 2025-12-31: The pages get a navigation bar and a home page with a search. The
+  status page shows the oldest and newest route times. The WHOIS stats query
+  handles `NULL`. The container runs as the `routewatch` user with the right
+  state directory
+- 2025-12-30: HTTP requests are logged as structured log lines. The HTTP
+  timeouts are longer. Prefix URLs with a slash in them route correctly. The
+  status page gets more metrics and a footer
+- 2025-12-29: The `Dockerfile` builds in stages and puts a source archive in the
+  image. SQLite reclaims space with incremental vacuum, which does not block
+- 2025-07-27: The first commit: RouteWatch, a BGP stream monitor

 # Future Steps
-
-None.
@@ -273,7 +273,7 @@ func TestVacuumReturnsFreePages(t *testing.T) {
 	writeTableChanges(t, db, table)

 	// The peer going down removes every prefix, and so every row.
-	table.PeerDown(peerA)
+	table.PeersDown([]string{peerA})
 	writeTableChanges(t, db, table)

 	var before int
@@ -107,7 +107,7 @@ func TestReadRouteTableGivesBackWhatWasWritten(t *testing.T) {

 	// A peer moves to another origin, one goes down and a new one comes.
 	announceTo(source, tablePrefixV4, asB, peerA, 60)
-	source.PeerDown(peerC)
+	source.PeersDown([]string{peerC})
 	announceTo(source, tablePrefixV6, asB, peerE, 70)

 	writeTableChanges(t, db, source)
@@ -133,7 +133,7 @@ func TestReadRouteTableGivesATableThatTakesLaterUpdates(t *testing.T) {
 	// another one goes down, and a new peer comes.
 	for _, table := range []*routetable.Table{source, read} {
 		table.Withdraw(netip.MustParsePrefix(tablePrefixV4), peerA)
-		table.PeerDown(peerB)
+		table.PeersDown([]string{peerB})
 		announceTo(table, tablePrefixShortV4, asB, peerD, 50)
 	}

@@ -10,10 +10,6 @@ import (
 	"git.eeqj.de/sneak/routewatch/internal/ristypes"
 )

-// walkBatch is how many prefixes the walk over the whole table reads in one
-// hold of the read lock. The updates waiting for the lock get it in between.
-const walkBatch = 10000
-
 // Overview holds figures about the whole table. Working them out takes a walk
 // over every prefix, so a caller asks for them now and then and keeps them.
 type Overview struct {
@@ -83,8 +79,9 @@ type OriginPeers struct {

 // Overview works out the table's overview. It lists at most maxListed bogon
 // announcements and at most maxListed prefixes with more than one origin AS:
-// the first in prefix order. It walks over every prefix, but holds the read
-// lock for walkBatch prefixes at a time.
+// the first in prefix order. It visits every prefix in the table, in batches
+// of walkBatch. After each batch, it lets the table's lock go for as long as
+// it held the lock for the batch.
 func (t *Table) Overview(maxListed int) Overview {
 	var overview Overview

@@ -114,15 +111,18 @@ func (t *Table) Overview(maxListed int) Overview {
 }

 // walkPrefixes calls visit with every prefix of the table and its origins. It
-// holds the read lock, but lets it go after every walkBatch prefixes, so the
-// updates waiting for it get in. A prefix that is added or removed in such a
-// gap may or may not be visited, as Go allows for a map that changes during a
-// range over it. visit must not keep origins once it returns.
+// holds the read lock for walkBatch prefixes at a time. After each batch, it
+// lets the table's lock go for as long as it held the lock for the batch.
+// During a walk over many batches, updates can then take the lock about half
+// of the time. The walk may or may not visit a prefix that is added or removed
+// while the lock is let go. Go allows this in a range over a map that changes.
+// visit must not keep origins once it returns.
 func (t *Table) walkPrefixes(visit func(prefix netip.Prefix, origins []*origin)) {
 	t.mu.RLock()
 	defer t.mu.RUnlock()

 	visited := 0
+	batchStart := time.Now()

 	for _, f := range []*family{&t.ipv4, &t.ipv6} {
 		for _, prefixes := range f.byLength {
@@ -131,8 +131,13 @@ func (t *Table) walkPrefixes(visit func(prefix netip.Prefix, origins []*origin))

 				visited++
 				if visited%walkBatch == 0 {
+					held := time.Since(batchStart)
+
 					t.mu.RUnlock()
+					time.Sleep(held)
 					t.mu.RLock()
+
+					batchStart = time.Now()
 				}
 			}
 		}
@@ -131,3 +131,61 @@ func TestWalkPrefixesLetsUpdatesIn(t *testing.T) {
 			"before its second batch")
 	}
 }
+
+// TestOverviewLetsUpdatesIn applies another peer's 1,000 announcements while
+// Overview walks a table with more prefixes than five of the walk's batches.
+// After each batch, the walk lets the lock go for as long as it held the lock.
+// So all 1,000 announcements must be applied before Overview returns. A walk
+// that takes the lock back at once lets in about one update per batch.
+func TestOverviewLetsUpdatesIn(t *testing.T) {
+	t.Parallel()
+
+	const (
+		asn       = 1000
+		peer      = "192.0.2.1"
+		otherPeer = "192.0.2.2"
+		// prefixCount is more prefixes than five of the walk's batches.
+		prefixCount   = 5*walkBatch + 1
+		announcements = 1000
+	)
+
+	routeTime := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+	table := New(Params{})
+	prefixes := make([]netip.Prefix, 0, prefixCount)
+	addr := netip.MustParseAddr("1.0.0.0")
+
+	for range prefixCount {
+		prefix := netip.PrefixFrom(addr, addr.BitLen())
+		table.Announce(prefix, asn, Route{Peer: peer, Time: routeTime})
+		prefixes = append(prefixes, prefix)
+		addr = addr.Next()
+	}
+
+	overviewDone := make(chan struct{})
+
+	go func() {
+		defer close(overviewDone)
+
+		table.Overview(0)
+	}()
+
+	// Wait until Overview holds the read lock. TryLock fails while a reader
+	// holds it.
+	for table.mu.TryLock() {
+		table.mu.Unlock()
+		runtime.Gosched()
+	}
+
+	for _, prefix := range prefixes[:announcements] {
+		table.Announce(prefix, asn, Route{Peer: otherPeer, Time: routeTime})
+	}
+
+	select {
+	case <-overviewDone:
+		t.Fatal("Overview returned before another peer's 1,000 announcements " +
+			"were applied")
+	default:
+	}
+
+	<-overviewDone
+}
@@ -227,7 +227,7 @@ func TestCounts(t *testing.T) {
 	})

 	// peerC was the last peer of the IPv6 prefix. It keeps its number.
-	table.PeerDown(peerC)
+	table.PeersDown([]string{peerC})
 	checkCounts(t, table, routetable.Counts{
 		Pairs:                2,
 		Peers:                3,
@@ -27,6 +27,11 @@ const (
 	// kept routes in order: each of its nodes holds up to 63 times.
 	keptTimesDegree = 32

+	// walkBatch is how many prefixes a walk over the whole table visits in
+	// one hold of the lock. Overview and PeersDown each walk the whole table.
+	// Callers waiting for the lock get it between batches.
+	walkBatch = 10000
+
 	ipv4Bits = 32
 	ipv6Bits = 128

@@ -200,24 +205,60 @@ func (t *Table) Withdraw(prefix netip.Prefix, peer string) {
 	}
 }

-// PeerDown applies a peer's session going down: the peer leaves every peer
-// set, and every route of it is dropped. When the peer carries any prefix, it
-// visits every prefix in the table.
-func (t *Table) PeerDown(peer string) {
+// PeersDown applies the sessions of peers going down: each of the peers leaves
+// every peer set, and every route of each is dropped. When any of them carries
+// a prefix, PeersDown visits every prefix in the table once, in batches of
+// walkBatch. After each batch, it lets the table's lock go for as long as it
+// held the lock for the batch. During a walk over many batches, reads and
+// updates can then take the lock about half of the time. An announcement by
+// one of the peers applied during the walk may be dropped too. So the caller
+// applies those peers' later updates only once PeersDown has returned.
+func (t *Table) PeersDown(peers []string) {
 	t.mu.Lock()
 	defer t.mu.Unlock()

-	number, known := t.peerNumbers[peer]
-	if !known || t.peerPrefixes[number] == 0 {
+	// numbers holds the number of each of the peers that carries a prefix.
+	numbers := make([]uint, 0, len(peers))
+
+	for _, peer := range peers {
+		number, known := t.peerNumbers[peer]
+		if known && t.peerPrefixes[number] > 0 {
+			numbers = append(numbers, number)
+		}
+	}
+
+	if len(numbers) == 0 {
 		return
 	}

+	visited := 0
+	batchStart := time.Now()
+
 	for _, f := range []*family{&t.ipv4, &t.ipv6} {
 		for _, prefixes := range f.byLength {
 			for prefix, origins := range prefixes {
-				o := originWithPeer(origins, number)
-				if o != nil {
-					t.leave(prefix, o, number)
+				for _, number := range numbers {
+					o := originWithPeer(origins, number)
+					if o != nil {
+						t.leave(prefix, o, number)
+
+						// leave may have removed an origin of the
+						// prefix, or the prefix itself.
+						origins = prefixes[prefix]
+					}
+				}
+
+				// Go allows the map to change before the next step of
+				// the range over it.
+				visited++
+				if visited%walkBatch == 0 {
+					held := time.Since(batchStart)
+
+					t.mu.Unlock()
+					time.Sleep(held)
+					t.mu.Lock()
+
+					batchStart = time.Now()
 				}
 			}
 		}
@@ -0,0 +1,69 @@
+package routetable
+
+import (
+	"net/netip"
+	"runtime"
+	"testing"
+	"time"
+)
+
+// TestPeersDownLetsReadsIn reads the table's counts again and again while a
+// peer that carries more than two batches of prefixes goes down. PeersDown lets
+// the lock go after every walkBatch prefixes, so a read must get in while the
+// peer still carries some of its prefixes but no longer all.
+func TestPeersDownLetsReadsIn(t *testing.T) {
+	t.Parallel()
+
+	const (
+		asn  = 1000
+		peer = "192.0.2.1"
+		// prefixCount is more prefixes than two of walkBatch.
+		prefixCount = 2*walkBatch + 1
+	)
+
+	routeTime := time.Date(2026, 1, 2, 3, 4, 5, 0, time.UTC)
+	table := New(Params{})
+	addr := netip.MustParseAddr("1.0.0.0")
+
+	for range prefixCount {
+		prefix := netip.PrefixFrom(addr, addr.BitLen())
+		table.Announce(prefix, asn, Route{Peer: peer, Time: routeTime})
+
+		addr = addr.Next()
+	}
+
+	// Hold a read lock until PeersDown waits for the lock, so that the first
+	// read below starts once PeersDown holds it. TryRLock fails once a writer
+	// waits.
+	table.mu.RLock()
+
+	peerDownDone := make(chan struct{})
+
+	go func() {
+		defer close(peerDownDone)
+
+		table.PeersDown([]string{peer})
+	}()
+
+	for table.mu.TryRLock() {
+		table.mu.RUnlock()
+		runtime.Gosched()
+	}
+
+	table.mu.RUnlock()
+
+	for {
+		routes := table.Counts().IPv4Routes
+		if routes > 0 && routes < prefixCount {
+			break
+		}
+
+		select {
+		case <-peerDownDone:
+			t.Fatal("no read got in while PeersDown ran")
+		default:
+		}
+	}
+
+	<-peerDownDone
+}
@@ -69,10 +69,10 @@ func withdraw(peer string) step {
 	}
 }

-// peerDown is the step of peer's session going down.
-func peerDown(peer string) step {
+// peersDown is the step of the sessions of peers going down.
+func peersDown(peers ...string) step {
 	return func(table *routetable.Table, _ netip.Prefix) {
-		table.PeerDown(peer)
+		table.PeersDown(peers)
 	}
 }

@@ -272,21 +272,28 @@ func TestWithdrawalsAndPeerDowns(t *testing.T) {
 		{
 			name: "a peer going down leaves the prefix",
 			steps: []step{announce(peerA, asA, 10), announce(peerB, asA, 20),
-				peerDown(peerB)},
+				peersDown(peerB)},
 			want: []routetable.Origin{{ASN: asA, Peers: []string{peerA},
 				Routes: []routetable.Route{routeOf(peerA, asA, 10)}}},
 		},
 		{
 			name: "a peer going down after it withdrew changes nothing",
 			steps: []step{announce(peerA, asA, 10), announce(peerB, asA, 20),
-				withdraw(peerB), peerDown(peerB)},
+				withdraw(peerB), peersDown(peerB)},
 			want: []routetable.Origin{{ASN: asA, Peers: []string{peerA},
 				Routes: []routetable.Route{routeOf(peerA, asA, 10)}}},
 		},
+		{
+			name: "peers going down together each leave the prefix",
+			steps: []step{announce(peerA, asA, 10), announce(peerB, asB, 20),
+				announce(peerC, asB, 30), peersDown(peerA, peerB)},
+			want: []routetable.Origin{{ASN: asB, Peers: []string{peerC},
+				Routes: []routetable.Route{routeOf(peerC, asB, 30)}}},
+		},
 	})
 }

-func TestPeerDownLeavesEveryPrefix(t *testing.T) {
+func TestPeersDownLeavesEveryPrefix(t *testing.T) {
 	t.Parallel()

 	table := routetable.New(routetable.Params{})
@@ -303,7 +310,7 @@ func TestPeerDownLeavesEveryPrefix(t *testing.T) {
 	}

 	table.Announce(prefixes[0], asB, routeOf(peerB, asB, 20))
-	table.PeerDown(peerA)
+	table.PeersDown([]string{peerA})

 	want := []routetable.Origin{{ASN: asB, Peers: []string{peerB},
 		Routes: []routetable.Route{routeOf(peerB, asB, 20)}}}
@@ -333,6 +340,32 @@ func TestPeerDownLeavesEveryPrefix(t *testing.T) {
 	}
 }

+// TestPeersDownTakesOutPeersOfDifferentPrefixes takes peerA and peerB out in
+// one PeersDown. peerA carries only prefixV4, and peerB only prefixV6. So
+// peerA's leaving removes prefixV4 before PeersDown looks for peerB there. Both
+// prefixes must then be gone.
+func TestPeersDownTakesOutPeersOfDifferentPrefixes(t *testing.T) {
+	t.Parallel()
+
+	table := routetable.New(routetable.Params{})
+	prefixes := []netip.Prefix{
+		netip.MustParsePrefix(prefixV4),
+		netip.MustParsePrefix(prefixV6),
+	}
+
+	table.Announce(prefixes[0], asA, routeOf(peerA, asA, 10))
+	table.Announce(prefixes[1], asB, routeOf(peerB, asB, 20))
+	table.PeersDown([]string{peerA, peerB})
+
+	for _, prefix := range prefixes {
+		got := table.Origins(prefix)
+		if got != nil {
+			t.Errorf("Origins(%s) = %+v after its only peer went down, want nil",
+				prefix, got)
+		}
+	}
+}
+
 func TestCountsOriginsWithoutKeptRoute(t *testing.T) {
 	t.Parallel()

@@ -358,7 +391,7 @@ func TestCountsOriginsWithoutKeptRoute(t *testing.T) {
 		{announce(peerC, asA, 30), 0},
 		{withdraw(peerB), 0},
 		{withdraw(peerC), 1},
-		{peerDown(peerA), 0},
+		{peersDown(peerA), 0},
 	}

 	for i, s := range steps {
@@ -464,7 +497,7 @@ func TestTakeChangesHoldsOnlyPairsThatChanged(t *testing.T) {
 	checkChanges(t, table, []change{}, map[string]uint{})

 	// peerA going down changes v4, the one prefix it carries.
-	table.PeerDown(peerA)
+	table.PeersDown([]string{peerA})
 	checkChanges(t, table, []change{
 		{Prefix: prefixV4, OriginASN: asA, Peers: []uint{1, 2},
 			Routes: []routetable.Route{
@@ -473,7 +506,7 @@ func TestTakeChangesHoldsOnlyPairsThatChanged(t *testing.T) {
 	}, map[string]uint{})

 	// peerA, which carries nothing now, goes down again.
-	table.PeerDown(peerA)
+	table.PeersDown([]string{peerA})
 	checkChanges(t, table, []change{}, map[string]uint{})
 }

@@ -617,7 +650,7 @@ func TestConcurrentUse(t *testing.T) {
 		func(round int) { table.Announce(prefix, asA, routeOf(peerA, asA, round)) },
 		func(round int) { table.Announce(prefix, asB, routeOf(peerB, asB, round)) },
 		func(int) { table.Withdraw(prefix, peerA) },
-		func(int) { table.PeerDown(peerB) },
+		func(int) { table.PeersDown([]string{peerB}) },
 		func(int) { table.PutBackChanges(table.TakeChanges(math.MaxInt)) },
 		func(int) { table.ChangeCount() },
 		func(int) { table.Lookup(prefix.Addr()) },
@@ -644,9 +644,8 @@ func TestShutdownDoesNotWaitForABlockedWrite(t *testing.T) {
 	}

 	rw.dbHandler = NewASHandler(store, log)
-	fill := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
 	startBlockedWrite(t, blocking, rw.dbHandler,
-		[]*ristypes.RISMessage{{Path: fill}})
+		[]*ristypes.RISMessage{{Path: pathOfASes(asnBatchSize)}})

 	ctx, cancel := context.WithTimeout(t.Context(), deadline)
 	defer cancel()
@@ -18,43 +18,34 @@ const (
 	// (asnBatchTimeout), so a queue smaller than asnBatchSize is fine.
 	asHandlerQueueSize = 20000

-	// asnBatchSize is the number of ASN operations to batch together
+	// asnBatchSize is the number of ASes in a full batch, which wakes the
+	// flush goroutine to write it.
 	asnBatchSize = 30000

-	// asnBatchMaxSize is the most ASN operations the batch holds while the
-	// flush goroutine writes the previous one: ten batches, about 10 MiB
-	// (README "Memory"). At this size HandleMessage waits until the flush
-	// goroutine takes the batch.
-	asnBatchMaxSize = 300000
-
 	// asnBatchTimeout is the maximum time to wait before flushing a batch
 	// DO NOT reduce this timeout - larger batches are more efficient
 	asnBatchTimeout = 2 * time.Second
 )

-// ASHandler processes Autonomous System Number (ASN) information extracted from
-// BGP UPDATE messages. It uses batched database operations to efficiently store
-// ASN data, collecting operations into batches that are flushed either when the
-// batch reaches a size threshold or after a timeout period.
+// ASHandler records every AS in the AS paths of BGP UPDATE messages. Its batch
+// holds the earliest and the latest time of each AS's updates. The flush
+// goroutine writes the batch to the database when it holds asnBatchSize ASes,
+// and every asnBatchTimeout.
 type ASHandler struct {
 	db     database.Store
 	logger *logger.Logger

-	// batchMaxSize is asnBatchMaxSize. Only HandleMessage reads it, so a test
-	// may lower it before it hands the handler a message.
-	batchMaxSize int
-
-	// Batching. mu guards batch and writing only: the flush goroutine takes
-	// the batch under mu and writes it after releasing mu, so HandleMessage
-	// waits for a database write only while batch is at batchMaxSize.
-	mu    sync.Mutex
-	batch []asnOp
-	// writing is how many operations the flush goroutine took from batch
-	// and has not finished writing.
-	writing int
-	// batchTaken is signalled when the flush goroutine takes batch; its L is
-	// &mu.
-	batchTaken  sync.Cond
+	// Batching. mu guards batch and writing only. The flush goroutine takes
+	// the batch under mu and writes it after releasing mu. So HandleMessage
+	// never waits for a database write.
+	mu sync.Mutex
+	// batch holds the earliest and the latest time of the updates for each AS
+	// since the flush goroutine last took it. It holds one entry per AS,
+	// however many updates arrive.
+	batch map[int]database.SeenTimes
+	// writing is how many ASes the flush goroutine took from batch and has
+	// not finished writing.
+	writing     int
 	batchFullCh chan struct{} // wakes the flush goroutine when batch is full
 	// stopCh hands Stop's context to the flush goroutine. It holds one, so
 	// Stop does not wait for a write in progress to hand it over.
@@ -62,16 +53,10 @@ type ASHandler struct {
 	done   chan struct{} // closed when the flush goroutine returns
 }

-type asnOp struct {
-	number    int
-	timestamp time.Time
-}
-
 // NewASHandler creates and returns a new ASHandler instance. It initializes
 // the batching system and starts a background goroutine that periodically
-// flushes accumulated ASN operations to the database. The caller must call
-// Stop when finished to ensure all pending operations are flushed and the
-// background goroutine is terminated.
+// writes the collected ASes to the database. The caller must call Stop when
+// finished, to write the pending ASes and end the background goroutine.
 func NewASHandler(db database.Store, logger *logger.Logger) *ASHandler {
 	return newASHandler(db, logger, asnBatchTimeout)
 }
@@ -83,15 +68,13 @@ func newASHandler(
 	db database.Store, logger *logger.Logger, batchTimeout time.Duration,
 ) *ASHandler {
 	h := &ASHandler{
-		db:           db,
-		logger:       logger,
-		batchMaxSize: asnBatchMaxSize,
-		batch:        make([]asnOp, 0, asnBatchSize),
-		batchFullCh:  make(chan struct{}, 1),
-		stopCh:       make(chan context.Context, 1),
-		done:         make(chan struct{}),
+		db:          db,
+		logger:      logger,
+		batch:       make(map[int]database.SeenTimes),
+		batchFullCh: make(chan struct{}, 1),
+		stopCh:      make(chan context.Context, 1),
+		done:        make(chan struct{}),
 	}
-	h.batchTaken.L = &h.mu

 	// Start the flush timer goroutine
 	go flushLoop(batchTimeout, h.batchFullCh, h.stopCh, h.done, h.flushBatch)
@@ -115,48 +98,25 @@ func (h *ASHandler) QueueCapacity() int {
 	return asHandlerQueueSize
 }

-// HandleMessage processes a RIS Live BGP message by extracting all ASNs from
-// the AS path and queuing them for batch insertion into the database. The
-// origin ASN and all transit ASNs are recorded with their associated
-// timestamps. When the batch reaches the configured size threshold, the flush
-// goroutine is woken to write it.
+// HandleMessage adds the time of msg to the batch entry of each AS in its AS
+// path, the origin AS and the members of an AS set included. When the batch
+// holds asnBatchSize ASes, HandleMessage wakes the flush goroutine to write it.
 func (h *ASHandler) HandleMessage(msg *ristypes.RISMessage) {
-	// Use the pre-parsed timestamp
-	timestamp := msg.ParsedTimestamp
-
-	originASN := msg.Path.Origin()
-
 	h.mu.Lock()
 	defer h.mu.Unlock()

-	// While the batch is at its maximum size, wait until the flush goroutine
-	// takes it. Meanwhile the handler takes nothing off its queue, which
-	// fills, and the streamer drops messages for it.
-	for len(h.batch) >= h.batchMaxSize {
-		h.batchTaken.Wait()
-	}
-
-	// Queue origin ASN operation
-	if originASN > 0 {
-		h.batch = append(h.batch, asnOp{
-			number:    originASN,
-			timestamp: timestamp,
-		})
-	}
-
-	// Also track all ASNs in the path, the members of an AS set included
+	// The origin AS is the last AS of the sequence, so the loop adds it too.
 	for _, asn := range slices.Concat(msg.Path.Sequence, msg.Path.Set) {
 		if asn > 0 {
-			h.batch = append(h.batch, asnOp{
-				number:    asn,
-				timestamp: timestamp,
-			})
+			seen := h.batch[asn]
+			seen.Add(msg.ParsedTimestamp)
+			h.batch[asn] = seen
 		}
 	}

 	// A full batch wakes the flush goroutine. If it is writing, the wake-up
-	// waits in batchFullCh and the batch keeps growing until the write ends
-	// or the batch reaches batchMaxSize.
+	// waits in batchFullCh and the batch keeps taking updates until the write
+	// ends.
 	if len(h.batch) >= asnBatchSize {
 		select {
 		case h.batchFullCh <- struct{}{}:
@@ -165,10 +125,11 @@ func (h *ASHandler) HandleMessage(msg *ristypes.RISMessage) {
 	}
 }

-// Stop stops the flush goroutine, which writes the operations the handler holds
-// before it returns, and waits for it until ctx ends. Once ctx has ended the
-// flush goroutine skips that last write, and a write still running is lost
-// when the process exits, so Stop logs how many operations are not written.
+// Stop stops the flush goroutine and waits for it until ctx ends. The flush
+// goroutine writes the batch before it returns, unless ctx has ended. A write
+// still running when the process exits is lost. Stop logs how many entries are
+// not written, in the batch being written and in the next batch. An AS in both
+// batches counts twice.
 func (h *ASHandler) Stop(ctx context.Context) {
 	h.stopCh <- ctx

@@ -183,14 +144,14 @@ func (h *ASHandler) Stop(ctx context.Context) {

 	if unwritten > 0 {
 		h.logger.Error("Stop deadline passed before the AS handler wrote "+
-			"its updates", "updates", unwritten)
+			"its batches", "batch_entries", unwritten)
 	}
 }

-// takeBatch returns the pending operations and leaves an empty batch in their
-// place for HandleMessage to fill. They count in writing until flushBatch has
-// written them.
-func (h *ASHandler) takeBatch() []asnOp {
+// takeBatch returns the pending ASes and leaves an empty batch in their place
+// for HandleMessage to fill. They count in writing until flushBatch has written
+// them.
+func (h *ASHandler) takeBatch() map[int]database.SeenTimes {
 	h.mu.Lock()
 	defer h.mu.Unlock()

@@ -200,8 +161,7 @@ func (h *ASHandler) takeBatch() []asnOp {

 	batch := h.batch
 	h.writing = len(batch)
-	h.batch = make([]asnOp, 0, asnBatchSize)
-	h.batchTaken.Broadcast()
+	h.batch = make(map[int]database.SeenTimes)

 	return batch
 }
@@ -214,21 +174,11 @@ func (h *ASHandler) flushBatch() {
 		return
 	}

-	// The earliest and the latest time the batch saw each AS. The batch holds
-	// several updates for an AS, from many peers, so a new AS is stored first
-	// seen at the earliest of them and last seen at the latest.
-	asns := make(map[int]database.SeenTimes)
-	for _, op := range batch {
-		seen := asns[op.number]
-		seen.Add(op.timestamp)
-		asns[op.number] = seen
-	}
-
 	// Process all ASNs in a single batch transaction
-	err := h.db.GetOrCreateASNBatch(asns)
+	err := h.db.GetOrCreateASNBatch(batch)
 	if err != nil {
 		h.logger.Error("Failed to process ASN batch",
-			"error", err, "count", len(asns))
+			"error", err, "count", len(batch))
 	}

 	h.mu.Lock()
@@ -5,28 +5,43 @@ import (
 	"slices"
 	"testing"

+	"git.eeqj.de/sneak/routewatch/internal/database"
 	"git.eeqj.de/sneak/routewatch/internal/logger"
+	"git.eeqj.de/sneak/routewatch/internal/ristypes"
 )

+// pathOfASes returns an AS path of n different ASes: AS 1 to AS n. With n up to
+// asnBatchSize, none of them is testASNA to testASND.
+func pathOfASes(n int) ristypes.ASPath {
+	sequence := make([]int, n)
+	for i := range sequence {
+		sequence[i] = i + 1
+	}
+
+	return ristypes.ASPath{Sequence: sequence}
+}
+
 // TestASHandlerStoresTheEarliestAndLatestTimesOfANewAS handles two updates
-// whose path carries an AS the database does not hold yet, the second 5
-// seconds after the first, in one batch into a real database. The AS is stored
-// first seen at the time of the first update and last seen at the time of the
-// second.
+// whose path carries an AS the database does not hold yet, in one batch into a
+// real database. The second is 5 seconds after the first, and the handler gets
+// it first. The AS is stored first seen at the time of the first update and
+// last seen at the time of the second.
 func TestASHandlerStoresTheEarliestAndLatestTimesOfANewAS(t *testing.T) {
 	t.Parallel()

 	db := newTestDatabase(t)

 	// Built without NewASHandler's flush goroutine, so the test flushes itself.
-	h := &ASHandler{db: db, logger: logger.New(), batchMaxSize: asnBatchMaxSize}
+	h := &ASHandler{
+		db: db, logger: logger.New(), batch: make(map[int]database.SeenTimes),
+	}

 	first := peerAnnouncement(testPeerIP, testV4Prefix)
 	second := peerAnnouncement(testPeerIP, testV4Prefix)
 	second.ParsedTimestamp = first.ParsedTimestamp.Add(secondUpdateAfter)

-	h.HandleMessage(first)
 	h.HandleMessage(second)
+	h.HandleMessage(first)
 	h.flushBatch()

 	asn, _, err := db.GetAS(t.Context(), testASNA)
@@ -54,7 +69,9 @@ func TestASHandlerRecordsNothingFromAPathWithASZero(t *testing.T) {
 	store := newMockStore()

 	// Built without NewASHandler's flush goroutine, so the test flushes itself.
-	h := &ASHandler{db: store, logger: logger.New(), batchMaxSize: asnBatchMaxSize}
+	h := &ASHandler{
+		db: store, logger: logger.New(), batch: make(map[int]database.SeenTimes),
+	}

 	msg := peerAnnouncement(testPeerIP, testV4Prefix)
 	msg.Path = decodePath(t, testASNA, 0, testASNB)
@@ -187,25 +187,33 @@ func (f *ASNFetcher) recordSuccess() {
 	f.statsMu.Unlock()
 }

-// recordFailure increases the interval on failed fetch using exponential backoff.
-func (f *ASNFetcher) recordFailure() {
+// lengthenInterval makes the interval 1.5 times as long, up to maxInterval.
+// A failed lookup and a skipped one both lengthen it.
+func (f *ASNFetcher) lengthenInterval() {
 	f.intervalMu.Lock()
-	f.consecutiveFails++
+	defer f.intervalMu.Unlock()

-	// Exponential backoff: multiply by 1.5, capped at max
 	newInterval := min(
 		f.currentInterval*backoffNumerator/backoffDenominator, maxInterval)

 	if newInterval != f.currentInterval {
-		f.logger.Debug("Increased fetch interval due to failure",
+		f.logger.Debug("Increased fetch interval",
 			"old_interval", f.currentInterval,
 			"new_interval", newInterval,
 			"consecutive_failures", f.consecutiveFails,
 		)
 		f.currentInterval = newInterval
 	}
+}
+
+// recordFailure counts a failed fetch and lengthens the interval.
+func (f *ASNFetcher) recordFailure() {
+	f.intervalMu.Lock()
+	f.consecutiveFails++
 	f.intervalMu.Unlock()

+	f.lengthenInterval()
+
 	// Record error time for stats, dropping those older than statsWindow
 	f.statsMu.Lock()
 	now := f.now()
@@ -291,9 +299,12 @@ func (f *ASNFetcher) fetchNextStale(ctx context.Context) {
 // The WHOIS client pauses an RIR's or NIC.br's server for whois.PauseTime
 // after the server refuses a query. Lookups at the other servers go on. IANA
 // is never paused, so a refusal by IANA is an ordinary failure. A lookup
-// whose RIR is paused fails with whois.ErrPaused. Such a lookup leaves the
-// AS stale, and counts as neither a success nor a failure. The lookups that
-// QueueImmediate asks for also run through fetchAndUpdate.
+// whose RIR is paused fails with whois.ErrPaused and is skipped. A skipped
+// lookup leaves the AS stale and is not counted as a failure. Like a
+// failure, a skipped lookup lengthens the interval. Each lookup asks IANA
+// before it finds its RIR paused, so with a one-second interval the fetcher
+// would ask IANA every second. The lookups that QueueImmediate asks for also
+// run through fetchAndUpdate.
 func (f *ASNFetcher) fetchAndUpdate(ctx context.Context, asn int) bool {
 	ctx, cancel := context.WithTimeout(ctx, time.Minute)
 	defer cancel()
@@ -317,6 +328,7 @@ func (f *ASNFetcher) fetchAndUpdate(ctx context.Context, asn int) bool {
 	if errors.Is(err, whois.ErrPaused) {
 		f.logger.Info("Skipped WHOIS lookup, the RIR's server is paused",
 			"asn", asn, "error", err)
+		f.lengthenInterval()

 		return false
 	}
@@ -196,6 +196,48 @@ func TestFetchAndUpdateWaitsOutAPause(t *testing.T) {
 	}
 }

+// TestFetchAndUpdateBacksOffDuringAPause looks up an AS at RIPE while RIPE
+// refuses the query. The refusal pauses RIPE for an hour, so every later
+// lookup in the test is skipped. The test sets the WHOIS client's clock and
+// looks the AS up again each time the interval has passed. Like a failure,
+// each skip must make the interval 1.5 times as long, up to one minute. The
+// skips must not count as failures.
+func TestFetchAndUpdateBacksOffDuringAPause(t *testing.T) {
+	t.Parallel()
+
+	f, _ := newFetcherWithWHOISAnswers(t, map[string]string{
+		ianaWHOISServer: ianaRefersToRIPE,
+		ripeWHOISServer: ripeAccessDenied,
+	})
+
+	now := time.Date(2026, 11, 2, 0, 0, 0, 0, time.UTC)
+	f.whoisClient.Now = func() time.Time { return now }
+
+	f.fetchAndUpdate(t.Context(), testASNA)
+
+	for i, want := range []time.Duration{
+		33750 * time.Millisecond,
+		50625 * time.Millisecond,
+		time.Minute,
+		time.Minute,
+	} {
+		now = now.Add(f.getInterval())
+
+		f.fetchAndUpdate(t.Context(), testASNA)
+
+		if got := f.getInterval(); got != want {
+			t.Errorf("interval after %d skipped lookups = %v, want %v",
+				i+1, got, want)
+		}
+	}
+
+	got := f.GetStats()
+	if got.ConsecutiveFails != 1 || got.ErrorsLastHour != 1 {
+		t.Errorf("%d failures in a row and %d errors, want 1 and 1",
+			got.ConsecutiveFails, got.ErrorsLastHour)
+	}
+}
+
 // TestFetchAndUpdateKeepsAskingIANA looks up an AS while IANA's server
 // refuses the connection. The test sets the WHOIS client's clock. The next
 // lookup comes a second before whois.PauseTime has passed. IANA is never
@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log/slog"
 	"slices"
 	"sync"
@@ -177,12 +178,14 @@ type stopLog struct {
 	Msg          string `json:"msg"`
 	Updates      int    `json:"updates"`
 	TableChanges int    `json:"table_changes"`
+	HeldMessages int    `json:"held_messages"`
 	Paths        int    `json:"paths"`
+	BatchEntries int    `json:"batch_entries"`
 }

 // newErrorLogger returns a logger that writes only errors, as JSON lines, to
 // logs.
-func newErrorLogger(logs *bytes.Buffer) *logger.Logger {
+func newErrorLogger(logs io.Writer) *logger.Logger {
 	return &logger.Logger{Logger: slog.New(slog.NewJSONHandler(logs,
 		&slog.HandlerOptions{Level: slog.LevelError}))}
 }
@@ -495,20 +498,20 @@ func TestPrefixHandlerStopCountsTheTableChangesOfAWriteInProgress(t *testing.T)
 	}
 }

+// TestASHandlerSkipsItsLastWriteAfterTheStopDeadline also checks what Stop
+// logs: the asnBatchSize entries of the held write and the entry for testASNB,
+// handled since, are not written.
 func TestASHandlerSkipsItsLastWriteAfterTheStopDeadline(t *testing.T) {
 	t.Parallel()

-	// Each message gives an update for its origin AS and one for each AS
-	// in its path: fill asnBatchSize+1, extra 2.
-	const wantUpdates = asnBatchSize + 1 + 2
+	const wantEntries = asnBatchSize + 1

 	var logs bytes.Buffer

 	store := newBlockingStore()
 	h := newASHandler(store, newErrorLogger(&logs), longerThanAnyTest)
-	fill := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
 	stopWhileAWriteIsBlocked(t, store, h, h.done,
-		[]*ristypes.RISMessage{{Path: fill}},
+		[]*ristypes.RISMessage{{Path: pathOfASes(asnBatchSize)}},
 		&ristypes.RISMessage{Path: ristypes.ASPath{Sequence: []int{testASNB}}})

 	store.mu.Lock()
@@ -518,26 +521,27 @@ func TestASHandlerSkipsItsLastWriteAfterTheStopDeadline(t *testing.T) {
 		t.Errorf("AS%d was written after the stop deadline", testASNB)
 	}

-	if logged := lastLogged(t, &logs); logged.Updates != wantUpdates {
-		t.Errorf("Stop logged %d updates not written, want %d",
-			logged.Updates, wantUpdates)
+	if logged := lastLogged(t, &logs); logged.BatchEntries != wantEntries {
+		t.Errorf("Stop logged %d batch entries not written, want %d",
+			logged.BatchEntries, wantEntries)
 	}
 }

 // TestASHandlerSkipsAFullBatchAfterTheStopDeadline hands the AS handler a full
 // batch while a write is held, so the batch's wake-up of the flush goroutine
-// waits. The stop deadline passes meanwhile. When the write ends, the flush
-// goroutine must stop instead of writing the batch.
+// waits. The full batch holds the fill's ASes again, and testASNB. The stop
+// deadline passes meanwhile. When the write ends, the flush goroutine must stop
+// instead of writing the batch.
 func TestASHandlerSkipsAFullBatchAfterTheStopDeadline(t *testing.T) {
 	t.Parallel()

 	store := newBlockingStore()
 	h := newASHandler(store, logger.New(), longerThanAnyTest)
-	fill := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
-	full := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNB}, asnBatchSize)}
+	fill := &ristypes.RISMessage{Path: pathOfASes(asnBatchSize)}
 	stopWhileAWriteIsBlocked(t, store, h, h.done,
-		[]*ristypes.RISMessage{{Path: fill}},
-		&ristypes.RISMessage{Path: full})
+		[]*ristypes.RISMessage{fill},
+		fill,
+		&ristypes.RISMessage{Path: ristypes.ASPath{Sequence: []int{testASNB}}})

 	store.mu.Lock()
 	defer store.mu.Unlock()
@@ -703,9 +707,8 @@ func TestASHandlerHandlesMessagesWhileAWriteIsBlocked(t *testing.T) {

 	store := newBlockingStore()
 	h := newASHandler(store, logger.New(), longerThanAnyTest)
-	fill := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
 	handleWhileAWriteIsBlocked(t, store, h,
-		[]*ristypes.RISMessage{{Path: fill}},
+		[]*ristypes.RISMessage{{Path: pathOfASes(asnBatchSize)}},
 		&ristypes.RISMessage{Path: ristypes.ASPath{Sequence: []int{testASNB}}})

 	store.mu.Lock()
@@ -762,25 +765,41 @@ func TestPrefixHandlerWaitsAtTheMaximumBatchSize(t *testing.T) {
 	}
 }

-func TestASHandlerWaitsAtTheMaximumBatchSize(t *testing.T) {
+// TestASHandlerNeverWaitsForAWrite starts a write that the store holds. Then it
+// hands the AS handler twenty messages whose paths each hold one AS
+// asnBatchSize times. HandleMessage must return each time, and the batch must
+// hold one entry, for that AS.
+func TestASHandlerNeverWaitsForAWrite(t *testing.T) {
 	t.Parallel()

+	const messages = 20
+
 	store := newBlockingStore()
 	h := newASHandler(store, logger.New(), longerThanAnyTest)
-	h.batchMaxSize = asnBatchSize
-	fill := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
-	toMax := ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, asnBatchSize)}
-	handleAtMaxBatchSize(t, store, h,
-		[]*ristypes.RISMessage{{Path: fill}},
-		[]*ristypes.RISMessage{{Path: toMax}},
-		&ristypes.RISMessage{Path: ristypes.ASPath{Sequence: []int{testASNB}}})

-	store.mu.Lock()
-	defer store.mu.Unlock()
+	defer stopInTime(t, h)
+	defer store.releaseWrites()

-	if !store.asns[testASNB] {
-		t.Errorf("Stop did not write AS%d, handled after the batch reached its "+
-			"maximum size", testASNB)
+	startBlockedWrite(t, store, h,
+		[]*ristypes.RISMessage{{Path: pathOfASes(asnBatchSize)}})
+
+	oneAS := &ristypes.RISMessage{
+		Path: ristypes.ASPath{Sequence: slices.Repeat([]int{testASNB}, asnBatchSize)},
+	}
+
+	if !returnsInTime(func() {
+		for range messages {
+			h.HandleMessage(oneAS)
+		}
+	}) {
+		t.Fatal("HandleMessage did not return while a database write was blocked")
+	}
+
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	if len(h.batch) != 1 {
+		t.Errorf("the batch holds %d entries for one AS, want 1", len(h.batch))
 	}
 }

@@ -844,13 +863,11 @@ func TestHandlersWakeTheFlushGoroutineWhenTheBatchIsFull(t *testing.T) {
 			batchSize: asnBatchSize,
 			handle: func(n int) chan struct{} {
 				h := &ASHandler{
-					batchMaxSize: asnBatchMaxSize,
-					batchFullCh:  make(chan struct{}, 1),
+					batch:       make(map[int]database.SeenTimes),
+					batchFullCh: make(chan struct{}, 1),
 				}
-				// The origin AS and each AS in the path are one update each.
-				h.HandleMessage(&ristypes.RISMessage{
-					Path: ristypes.ASPath{Sequence: slices.Repeat([]int{testASNA}, n-1)},
-				})
+				// Each of the path's n ASes is one entry of the batch.
+				h.HandleMessage(&ristypes.RISMessage{Path: pathOfASes(n)})

 				return h.batchFullCh
 			},
@@ -44,6 +44,21 @@ const (
 	// most one pair. So the million pairs that a full-table peer's session
 	// going down changes are written in about a minute.
 	maxTableChangesPerWrite = 20000
+
+	// maxHeldBackMessages is the most messages the handler holds back from
+	// peers whose session went down. A peer's messages are held back from
+	// the moment its session goes down until peerDown has applied them. If
+	// peerDown is running at that moment, the peer waits for the rest of
+	// peerDown's current PeersDown call. The peer also waits while peerDown
+	// applies the messages held back from that call's peers, those that
+	// arrive meanwhile included. The next PeersDown call takes the peer out.
+	// Once that call returns, peerDown applies the messages held back from
+	// that call's peers, one peer after another, in the order the call lists
+	// them. A held-back message that says the peer's session went down again
+	// makes the peer's later messages wait for the next call. A message takes
+	// about 1 KiB, so 150,000 take about 150 MiB (README "Memory"). At this
+	// number HandleMessage waits until one of them is applied.
+	maxHeldBackMessages = 150000
 )

 // PrefixHandler keeps the routing table in memory current from the feed. It
@@ -52,6 +67,17 @@ const (
 // does an announcement whose AS path is empty or holds AS 0 anywhere. A peer
 // whose BGP session goes down leaves every prefix.
 //
+// The table's PeersDown applies sessions going down. It visits every prefix,
+// which takes seconds on a full table. So the handler runs PeersDown on a
+// separate goroutine and goes on taking messages meanwhile. One PeersDown runs
+// at a time. The next one takes every peer whose session went down since the
+// previous one began. PeersDown lets the table's lock go about half of the
+// time, so the handler applies other peers' messages while PeersDown runs. The
+// handler holds back a down peer's later messages until peerDown applies them,
+// as the doc of maxHeldBackMessages describes. It applies them in order, one at
+// a time, and takes new messages in between. It holds back at most
+// maxHeldBackMessages messages.
+//
 // Each flush writes the table's changes to the database. It also stores each
 // prefix the updates name with the time it was first seen.
 type PrefixHandler struct {
@@ -67,7 +93,7 @@ type PrefixHandler struct {
 	// give a smaller one.
 	tableChangesPerWrite int

-	// Batching. mu guards batch, writing and writingTableChanges only: the
+	// Batching. mu guards batch, writing and writingTableChanges: the
 	// flush goroutine takes them under mu and writes them after releasing
 	// mu, so HandleMessage waits for a database write only while batch is at
 	// batchMaxSize.
@@ -87,6 +113,26 @@ type PrefixHandler struct {
 	// Stop does not wait for a write in progress to hand it over.
 	stopCh chan context.Context
 	done   chan struct{} // closed when the flush goroutine returns
+
+	// Peers whose session went down. heldBack, under mu, holds each such
+	// peer's later messages, in order, until the peer has left every prefix
+	// and they are applied. A peer with no such messages yet has an empty
+	// entry. heldCount, under mu, is how many messages heldBack holds.
+	// heldTaken is signalled each time a held-back message is taken out to
+	// be applied; its L is &mu.
+	heldBack  map[string][]*ristypes.RISMessage
+	heldCount int
+	heldTaken sync.Cond
+	// downPeers, under mu, lists the peers whose session went down and that
+	// the next PeersDown takes. peerDownRunning, under mu, says whether
+	// peerDown is running. peerDowns counts the peerDown goroutines that have
+	// not returned.
+	downPeers       []string
+	peerDownRunning bool
+	peerDowns       sync.WaitGroup
+	// tablePeersDown is the table's PeersDown. Only peerDown calls it, so a
+	// test may replace it before it hands the handler a message.
+	tablePeersDown func(peers []string)
 }

 // seenPrefix is what the batch keeps of an update: the prefix it names and its
@@ -150,8 +196,11 @@ func newPrefixHandler(
 		batchFullCh:          make(chan struct{}, 1),
 		stopCh:               make(chan context.Context, 1),
 		done:                 make(chan struct{}),
+		heldBack:             make(map[string][]*ristypes.RISMessage),
+		tablePeersDown:       table.PeersDown,
 	}
 	h.batchTaken.L = &h.mu
+	h.heldTaken.L = &h.mu

 	// Start the flush timer goroutine
 	go flushLoop(batchTimeout, h.batchFullCh, h.stopCh, h.done, h.flushBatch)
@@ -179,11 +228,100 @@ func (h *PrefixHandler) QueueCapacity() int {
 	return prefixHandlerQueueSize
 }

-// HandleMessage processes a message to track prefix information
+// HandleMessage processes a message to track prefix information. A message
+// from a peer whose session went down is held back until peerDown applies it.
 func (h *PrefixHandler) HandleMessage(msg *ristypes.RISMessage) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	// While maxHeldBackMessages messages are held back, wait until one of them
+	// is taken out to be applied. Meanwhile the handler takes nothing off its
+	// queue, as at batchMaxSize.
+	for h.heldCount >= maxHeldBackMessages {
+		h.heldTaken.Wait()
+	}
+
+	held, goingDown := h.heldBack[msg.Peer]
+	if goingDown {
+		h.heldBack[msg.Peer] = append(held, msg)
+		h.heldCount++
+
+		return
+	}
+
+	h.applyMessage(msg)
+}
+
+// HeldBackCount returns how many messages the handler holds back from peers
+// whose session went down. The status page shows it.
+func (h *PrefixHandler) HeldBackCount() int {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+
+	return h.heldCount
+}
+
+// Stop waits for every PeersDown the handler started and for the messages held
+// back meanwhile to be applied. It gives up this wait once ctx ends. Then Stop
+// stops the flush goroutine and waits for it until ctx ends. The flush
+// goroutine makes one last flush before it returns. That flush writes at most
+// tableChangesPerWrite of the routing table's changes, and the prefixes of the
+// updates the handler holds. Once ctx has ended the flush goroutine skips that
+// last flush, and a write still running is lost when the process exits. A
+// failed write of the table's changes is not retried either. Stop logs how
+// many updates and table changes are not written. It also logs how many
+// held-back messages are not applied. The caller calls Stop once its last
+// HandleMessage has returned.
+func (h *PrefixHandler) Stop(ctx context.Context) {
+	peerDownsDone := make(chan struct{})
+
+	go func() {
+		h.peerDowns.Wait()
+		close(peerDownsDone)
+	}()
+
+	select {
+	case <-peerDownsDone:
+	case <-ctx.Done():
+	}
+
+	h.stopCh <- ctx
+
+	select {
+	case <-h.done:
+	case <-ctx.Done():
+	}
+
+	h.mu.Lock()
+	unwritten := h.writing + len(h.batch)
+	tableChanges := h.writingTableChanges + h.table.ChangeCount()
+	heldMessages := h.heldCount
+	h.mu.Unlock()
+
+	if unwritten == 0 && tableChanges == 0 && heldMessages == 0 {
+		return
+	}
+
+	if ctx.Err() != nil {
+		h.logger.Error("Stop deadline passed before the prefix handler wrote "+
+			"its updates", "updates", unwritten, "table_changes", tableChanges,
+			"held_messages", heldMessages)
+
+		return
+	}
+
+	h.logger.Error("The prefix handler stopped before it wrote everything",
+		"updates", unwritten, "table_changes", tableChanges,
+		"held_messages", heldMessages)
+}
+
+// applyMessage applies msg. The caller holds mu. A peer's session going down
+// has the peer leave every prefix. An update is applied to the routing table,
+// and its prefixes join the batch.
+func (h *PrefixHandler) applyMessage(msg *ristypes.RISMessage) {
 	if msg.Type == ristypes.MessageTypeState {
 		if msg.State == ristypes.StateDown {
-			h.table.PeerDown(msg.Peer)
+			h.startPeerDown(msg.Peer)
 		}

 		return
@@ -198,9 +336,6 @@ func (h *PrefixHandler) HandleMessage(msg *ristypes.RISMessage) {
 	// the path after the rest of it.
 	path := slices.Concat(msg.Path.Sequence, msg.Path.Set)

-	h.mu.Lock()
-	defer h.mu.Unlock()
-
 	// While the batch is at its maximum size, wait until the flush goroutine
 	// takes it. Meanwhile the handler takes nothing off its queue, which
 	// fills, and the streamer drops messages for it.
@@ -261,39 +396,88 @@ func (h *PrefixHandler) HandleMessage(msg *ristypes.RISMessage) {
 	}
 }

-// Stop stops the flush goroutine, which makes one last flush before it returns,
-// and waits for it until ctx ends. That flush writes at most
-// tableChangesPerWrite of the routing table's changes, and the prefixes of
-// the updates the handler holds. Once ctx has ended the flush goroutine skips
-// that last flush, and a write still running is lost when the process exits. A
-// failed write of the table's changes is not retried either. Stop logs how many
-// updates and how many of the table's changes are not written.
-func (h *PrefixHandler) Stop(ctx context.Context) {
-	h.stopCh <- ctx
-
-	select {
-	case <-h.done:
-	case <-ctx.Done():
+// startPeerDown adds peer to downPeers. It starts peerDown on a new goroutine
+// unless peerDown is running. The caller holds mu. The peer's messages are
+// held back until peerDown has applied them. Messages held back for an earlier
+// session of the peer going down, and not yet applied, stay held back.
+func (h *PrefixHandler) startPeerDown(peer string) {
+	_, goingDown := h.heldBack[peer]
+	if !goingDown {
+		h.heldBack[peer] = []*ristypes.RISMessage{}
 	}

-	h.mu.Lock()
-	unwritten := h.writing + len(h.batch)
-	tableChanges := h.writingTableChanges + h.table.ChangeCount()
-	h.mu.Unlock()
+	h.downPeers = append(h.downPeers, peer)

-	if unwritten == 0 && tableChanges == 0 {
+	if h.peerDownRunning {
 		return
 	}

-	if ctx.Err() != nil {
-		h.logger.Error("Stop deadline passed before the prefix handler wrote "+
-			"its updates", "updates", unwritten, "table_changes", tableChanges)
+	h.peerDownRunning = true
+	h.peerDowns.Add(1)

-		return
+	go h.peerDown()
+}
+
+// peerDown takes every peer in downPeers and runs the table's PeersDown for
+// them. Then it applies the messages held back from each of those peers. It
+// repeats this until downPeers is empty.
+func (h *PrefixHandler) peerDown() {
+	defer h.peerDowns.Done()
+
+	for {
+		h.mu.Lock()
+
+		peers := h.downPeers
+		h.downPeers = nil
+
+		if len(peers) == 0 {
+			h.peerDownRunning = false
+			h.mu.Unlock()
+
+			return
+		}
+
+		h.mu.Unlock()
+
+		h.tablePeersDown(peers)
+
+		for _, peer := range peers {
+			h.applyHeldBack(peer)
+		}
 	}
+}

-	h.logger.Error("The prefix handler stopped before it wrote everything",
-		"updates", unwritten, "table_changes", tableChanges)
+// applyHeldBack applies the messages held back from peer, in order. It takes
+// mu for one message at a time, so HandleMessage takes new messages in
+// between. The peer's new messages join the end of the held-back ones. A
+// held-back message that says the peer's session went down again adds the
+// peer to downPeers. The rest stay held back until the next PeersDown has
+// returned.
+func (h *PrefixHandler) applyHeldBack(peer string) {
+	for {
+		h.mu.Lock()
+
+		held := h.heldBack[peer]
+		if len(held) == 0 {
+			delete(h.heldBack, peer)
+			h.mu.Unlock()
+
+			return
+		}
+
+		msg := held[0]
+		held[0] = nil // so that the message is freed once applied
+		h.heldBack[peer] = held[1:]
+		h.heldCount--
+		h.heldTaken.Broadcast()
+		h.applyMessage(msg)
+		h.mu.Unlock()
+
+		if msg.Type == ristypes.MessageTypeState &&
+			msg.State == ristypes.StateDown {
+			return
+		}
+	}
 }

 // takeBatch returns the pending updates and leaves an empty batch in their
@@ -237,6 +237,83 @@ func TestPrefixHandlerStopLogsNothingWhenItWroteEverything(t *testing.T) {
 	}
 }

+// TestPrefixHandlerStopLogsTheMessagesHeldBack stops a prefix handler with a
+// deadline that has passed, while a peer's PeersDown is held up and one message
+// of the peer is held back. Stop must log that message as not applied.
+func TestPrefixHandlerStopLogsTheMessagesHeldBack(t *testing.T) {
+	t.Parallel()
+
+	var logs bytes.Buffer
+
+	h := newPrefixHandler(newMockStore(), newErrorLogger(&logs),
+		routetable.New(routetable.Params{}), longerThanAnyTest,
+		maxTableChangesPerWrite)
+
+	release := holdUpPeersDown(h)
+	defer close(release)
+
+	h.HandleMessage(peerAnnouncement(testPeerIP, testV4Prefix))
+	h.HandleMessage(sessionDown())
+	h.HandleMessage(peerAnnouncement(testPeerIP, testV6Prefix))
+
+	ctx, cancel := context.WithCancel(t.Context())
+	cancel()
+	h.Stop(ctx)
+
+	logged := lastLogged(t, &logs)
+	if logged.HeldMessages != 1 {
+		t.Errorf("Stop logged %d held messages not applied, want 1",
+			logged.HeldMessages)
+	}
+}
+
+// TestPrefixHandlerStopWaitsForTheMessagesHeldBack stops a prefix handler
+// while a peer's PeersDown is held up and an announcement of the peer is held
+// back. Stop must wait. Once the PeersDown is let go and Stop returns, the
+// announcement must be in the database.
+func TestPrefixHandlerStopWaitsForTheMessagesHeldBack(t *testing.T) {
+	t.Parallel()
+
+	db := newTestDatabase(t)
+	h := newPrefixHandler(db, logger.New(), routetable.New(routetable.Params{}),
+		longerThanAnyTest, maxTableChangesPerWrite)
+
+	release := holdUpPeersDown(h)
+	h.HandleMessage(sessionDown())
+	h.HandleMessage(peerAnnouncement(testPeerIP, testV4Prefix))
+
+	stopped := make(chan struct{})
+
+	go func() {
+		h.Stop(t.Context())
+		close(stopped)
+	}()
+
+	select {
+	case <-stopped:
+		t.Error("Stop returned while a PeersDown was held up")
+	case <-time.After(stillWaitingAfter):
+	}
+
+	close(release)
+
+	select {
+	case <-stopped:
+	case <-time.After(stepTimeout):
+		t.Fatalf("Stop did not return within %s of the PeersDown's release",
+			stepTimeout)
+	}
+
+	read, err := db.ReadRouteTable(t.Context())
+	if err != nil {
+		t.Fatalf("ReadRouteTable: %v", err)
+	}
+
+	checkTableOrigins(t, read, map[string]map[int][]string{
+		testV4Prefix: {testASNB: {testPeerIP}},
+	})
+}
+
 // longerThanAnyTest is a timer interval that no test lasts. A test gives it to
 // newPrefixHandler, newASHandler, newPeerHandler or newPeeringHandler when the
 // handler must write only when its batch is full, when the test says, or on
@@ -247,15 +324,32 @@ const longerThanAnyTest = time.Hour
 // applies the updates to an empty routing table. It is built without
 // NewPrefixHandler's flush goroutine, so the test flushes itself.
 func prefixHandlerWithoutTimer(store database.Store) *PrefixHandler {
+	table := routetable.New(routetable.Params{})
+
 	return &PrefixHandler{
 		db:                   store,
 		logger:               logger.New(),
-		table:                routetable.New(routetable.Params{}),
+		table:                table,
 		batchMaxSize:         prefixBatchMaxSize,
 		tableChangesPerWrite: maxTableChangesPerWrite,
+		heldBack:             make(map[string][]*ristypes.RISMessage),
+		tablePeersDown:       table.PeersDown,
 	}
 }

+// holdUpPeersDown makes each PeersDown of h wait until the returned channel is
+// closed, as another peer's long PeersDown would hold it up. The test calls it
+// before it hands h a message.
+func holdUpPeersDown(h *PrefixHandler) chan struct{} {
+	release := make(chan struct{})
+	h.tablePeersDown = func(peers []string) {
+		<-release
+		h.table.PeersDown(peers)
+	}
+
+	return release
+}
+
 // newTestDatabase opens a database in a new temporary directory. It is closed
 // when the test ends.
 func newTestDatabase(t *testing.T) *database.Database {
@@ -7,8 +7,10 @@ import (
 	"log/slog"
 	"net/netip"
 	"reflect"
+	"runtime"
 	"slices"
 	"strings"
+	"sync"
 	"testing"
 	"time"

@@ -101,6 +103,359 @@ func TestPrefixHandlerAppliesUpdatesToTheRoutingTable(t *testing.T) {
 	})
 }

+// TestPrefixHandlerTakesMessagesWhileAPeerGoesDown holds up the PeersDown of a
+// peer whose session went down, as another peer's long PeersDown would. The
+// handler must go on taking messages. It applies another peer's announcement
+// at once. It holds back these messages of the down peer, in this order:
+//   - an announcement;
+//   - its session going down again;
+//   - a second announcement.
+//
+// HeldBackCount must count them. Once the PeersDown calls have returned, the
+// down peer must carry only the prefix of the second announcement.
+func TestPrefixHandlerTakesMessagesWhileAPeerGoesDown(t *testing.T) {
+	t.Parallel()
+
+	const heldMessages = 3
+
+	h := prefixHandlerWithoutTimer(newMockStore())
+	release := holdUpPeersDown(h)
+	h.HandleMessage(peerAnnouncement(testPeerIP, testV4Prefix))
+
+	handled := returnsInTime(func() {
+		for _, msg := range []*ristypes.RISMessage{
+			sessionDown(),
+			peerAnnouncement(secondPeerIP, otherV4Prefix),
+			peerAnnouncement(testPeerIP, testV6Prefix),
+			sessionDown(),
+			peerAnnouncement(testPeerIP, setV4Prefix),
+		} {
+			h.HandleMessage(msg)
+		}
+	})
+	if !handled {
+		t.Fatalf("the handler did not take the messages after the session "+
+			"went down within %s", stepTimeout)
+	}
+
+	checkTableOrigins(t, h.table, map[string]map[int][]string{
+		testV4Prefix:  {testASNB: {testPeerIP}},
+		otherV4Prefix: {testASNB: {secondPeerIP}},
+		testV6Prefix:  {},
+		setV4Prefix:   {},
+	})
+
+	if h.HeldBackCount() != heldMessages {
+		t.Errorf("HeldBackCount() = %d, want %d", h.HeldBackCount(),
+			heldMessages)
+	}
+
+	close(release)
+
+	if !returnsInTime(h.peerDowns.Wait) {
+		t.Fatalf("the PeersDown calls did not return within %s", stepTimeout)
+	}
+
+	checkTableOrigins(t, h.table, map[string]map[int][]string{
+		testV4Prefix:  {},
+		otherV4Prefix: {testASNB: {secondPeerIP}},
+		testV6Prefix:  {},
+		setV4Prefix:   {testASNB: {testPeerIP}},
+	})
+}
+
+// TestPrefixHandlerTakesPeersDownTogether has four peers announce testV4Prefix.
+// It holds up the PeersDown of the first peer, whose session goes down.
+// Meanwhile the sessions of the three others go down, and each of them
+// announces otherV4Prefix. Once the first PeersDown is let go, the next one
+// must take the three others together. No peer may then carry testV4Prefix,
+// and the three others must carry otherV4Prefix.
+func TestPrefixHandlerTakesPeersDownTogether(t *testing.T) {
+	t.Parallel()
+
+	others := []string{secondPeerIP, thirdPeerIP, fourthPeerIP}
+	h := prefixHandlerWithoutTimer(newMockStore())
+
+	// calls receives the peers of each PeersDown, with room for one call
+	// for each peer.
+	calls := make(chan []string, len(others)+1)
+	release := make(chan struct{})
+	h.tablePeersDown = func(peers []string) {
+		calls <- slices.Clone(peers)
+
+		<-release
+		h.table.PeersDown(peers)
+	}
+
+	for _, peer := range append([]string{testPeerIP}, others...) {
+		h.HandleMessage(peerAnnouncement(peer, testV4Prefix))
+	}
+
+	h.HandleMessage(sessionDown())
+
+	select {
+	case <-calls:
+	case <-time.After(stepTimeout):
+		t.Fatalf("PeersDown did not begin within %s", stepTimeout)
+	}
+
+	for _, peer := range others {
+		h.HandleMessage(sessionDownOf(peer))
+		h.HandleMessage(peerAnnouncement(peer, otherV4Prefix))
+	}
+
+	close(release)
+
+	if !returnsInTime(h.peerDowns.Wait) {
+		t.Fatalf("the PeersDown calls did not return within %s", stepTimeout)
+	}
+
+	close(calls)
+
+	later := make([][]string, 0, len(calls))
+	for peers := range calls {
+		later = append(later, peers)
+	}
+
+	if !reflect.DeepEqual(later, [][]string{others}) {
+		t.Errorf("the PeersDown calls after the first took %v, want %v "+
+			"together", later, others)
+	}
+
+	checkTableOrigins(t, h.table, map[string]map[int][]string{
+		testV4Prefix:  {},
+		otherV4Prefix: {testASNB: others},
+	})
+}
+
+// TestPrefixHandlerAppliesMessagesWhilePeersDownRuns gives a peer 50,000
+// prefixes and hands the prefix handler that peer's session going down. The
+// table's PeersDown then visits the prefixes in five batches. Once PeersDown
+// has begun, the handler is handed 1,000 announcements of another peer. The
+// handler must apply them all before PeersDown ends, while the down peer still
+// carries some of its prefixes.
+func TestPrefixHandlerAppliesMessagesWhilePeersDownRuns(t *testing.T) {
+	t.Parallel()
+
+	const (
+		// downPeerPrefixes is five times the 10,000 prefixes PeersDown visits
+		// in one hold of the table's lock.
+		downPeerPrefixes = 50000
+		// otherPeerMessages is far more messages than the handler applies
+		// while PeersDown runs, if PeersDown takes the lock back at once after
+		// each batch. The handler then applies only a few for each batch.
+		otherPeerMessages = 1000
+		// firstOtherAddr is the address of the other peer's first prefix.
+		firstOtherAddr = "2001:db8:2::"
+	)
+
+	h := prefixHandlerWithoutTimer(newMockStore())
+	announceManyPrefixes(h.table, downPeerPrefixes)
+
+	h.HandleMessage(sessionDown())
+
+	// Wait until PeersDown has begun: the down peer has left some of its
+	// prefixes. The down peer's prefixes are IPv4 and the other peer's are
+	// IPv6, so the counts tell them apart.
+	for h.table.Counts().IPv4Routes == downPeerPrefixes {
+		runtime.Gosched()
+	}
+
+	// Each announcement names the /128 of the next address.
+	addr := netip.MustParseAddr(firstOtherAddr)
+	for range otherPeerMessages {
+		h.HandleMessage(peerAnnouncement(secondPeerIP,
+			netip.PrefixFrom(addr, addr.BitLen()).String()))
+
+		addr = addr.Next()
+	}
+
+	counts := h.table.Counts()
+	if counts.IPv6Routes != otherPeerMessages {
+		t.Errorf("the other peer carries %d prefixes, want %d",
+			counts.IPv6Routes, otherPeerMessages)
+	}
+
+	if counts.IPv4Routes == 0 {
+		t.Errorf("PeersDown ended before the handler applied the other peer's "+
+			"%d announcements", otherPeerMessages)
+	}
+
+	if !returnsInTime(h.peerDowns.Wait) {
+		t.Fatalf("the PeersDown did not return within %s", stepTimeout)
+	}
+}
+
+// TestPrefixHandlerTakesMessagesWhileAReturningPeerSendsItsTable gives a peer
+// 50,000 prefixes and hands the prefix handler that peer's session going down.
+// Once PeersDown has begun, the peer comes back and sends more announcements
+// than the handler's queue holds, as a peer that sends its whole table again
+// does. The handler must hold them back and go on taking messages. Another
+// peer's announcement, handed next, must be applied before PeersDown ends.
+func TestPrefixHandlerTakesMessagesWhileAReturningPeerSendsItsTable(t *testing.T) {
+	t.Parallel()
+
+	const (
+		// downPeerPrefixes is five times the 10,000 prefixes PeersDown visits
+		// in one hold of the table's lock.
+		downPeerPrefixes  = 50000
+		returningMessages = prefixHandlerQueueSize + 1
+	)
+
+	table := routetable.New(routetable.Params{})
+	announceManyPrefixes(table, downPeerPrefixes)
+
+	h := newPrefixHandler(newMockStore(), logger.New(), table,
+		longerThanAnyTest, maxTableChangesPerWrite)
+	defer stopInTime(t, h)
+
+	h.HandleMessage(sessionDown())
+
+	// Wait until PeersDown has begun: the down peer has left some of its
+	// prefixes, which are all IPv4.
+	for h.table.Counts().IPv4Routes == downPeerPrefixes {
+		runtime.Gosched()
+	}
+
+	returning := peerAnnouncement(testPeerIP, testV6Prefix)
+
+	if !returnsInTime(func() {
+		for range returningMessages {
+			h.HandleMessage(returning)
+		}
+
+		h.HandleMessage(peerAnnouncement(secondPeerIP, testV6Prefix))
+	}) {
+		t.Fatalf("the handler did not take the messages within %s", stepTimeout)
+	}
+
+	if h.table.Counts().IPv4Routes == 0 {
+		t.Error("PeersDown ended before the handler took the other peer's " +
+			"announcement")
+	}
+
+	checkTableOrigins(t, h.table, map[string]map[int][]string{
+		testV6Prefix: {testASNB: {secondPeerIP}},
+	})
+
+	if !returnsInTime(h.peerDowns.Wait) {
+		t.Fatalf("the PeersDown did not return within %s", stepTimeout)
+	}
+
+	checkTableOrigins(t, h.table, map[string]map[int][]string{
+		testV6Prefix: {testASNB: {testPeerIP, secondPeerIP}},
+	})
+}
+
+// TestPrefixHandlerTakesMessagesWhileItAppliesHeldBackOnes holds back many
+// messages of a peer whose session went down. Each names a prefix that does
+// not parse, so applying it logs an error. Each log write takes a
+// millisecond. While the handler applies the held-back messages, it must take
+// another peer's announcement.
+func TestPrefixHandlerTakesMessagesWhileItAppliesHeldBackOnes(t *testing.T) {
+	t.Parallel()
+
+	const (
+		// heldMessages take the handler at least a second to apply.
+		heldMessages = 1000
+		badPrefix    = "not a prefix"
+	)
+
+	logs := &slowWriter{firstWrite: make(chan struct{})}
+	h := newPrefixHandler(newMockStore(), newErrorLogger(logs),
+		routetable.New(routetable.Params{}), longerThanAnyTest,
+		maxTableChangesPerWrite)
+
+	defer stopInTime(t, h)
+
+	release := holdUpPeersDown(h)
+	h.HandleMessage(sessionDown())
+
+	for range heldMessages {
+		h.HandleMessage(peerAnnouncement(testPeerIP, badPrefix))
+	}
+
+	close(release)
+
+	select {
+	case <-logs.firstWrite:
+	case <-time.After(stepTimeout):
+		t.Fatal("the handler did not start to apply the held-back messages")
+	}
+
+	if !returnsInTime(func() {
+		h.HandleMessage(peerAnnouncement(secondPeerIP, otherV4Prefix))
+	}) {
+		t.Fatalf("HandleMessage did not return within %s", stepTimeout)
+	}
+
+	h.mu.Lock()
+	left := len(h.heldBack[testPeerIP])
+	h.mu.Unlock()
+
+	if left == 0 {
+		t.Error("the handler took another peer's announcement only once it " +
+			"had applied every held-back message")
+	}
+}
+
+// TestPrefixHandlerWaitsAtTheMaximumHeldBack holds up the PeersDown of a peer
+// whose session went down. It hands the handler maxHeldBackMessages messages
+// of that peer. HandleMessage must then wait, even for another peer's
+// message, until the PeersDown returns and a held-back message is applied.
+func TestPrefixHandlerWaitsAtTheMaximumHeldBack(t *testing.T) {
+	t.Parallel()
+
+	h := newPrefixHandler(newMockStore(), logger.New(),
+		routetable.New(routetable.Params{}), longerThanAnyTest,
+		maxTableChangesPerWrite)
+	defer stopInTime(t, h)
+
+	release := holdUpPeersDown(h)
+	h.HandleMessage(sessionDown())
+
+	held := peerAnnouncement(testPeerIP, testV6Prefix)
+	for range maxHeldBackMessages {
+		h.HandleMessage(held)
+	}
+
+	returned := make(chan struct{})
+
+	go func() {
+		h.HandleMessage(peerAnnouncement(secondPeerIP, otherV4Prefix))
+		close(returned)
+	}()
+
+	select {
+	case <-returned:
+		t.Error("HandleMessage returned while maxHeldBackMessages messages " +
+			"were held back")
+	case <-time.After(stillWaitingAfter):
+	}
+
+	close(release)
+
+	select {
+	case <-returned:
+	case <-time.After(stepTimeout):
+		t.Fatal("HandleMessage did not return after the PeersDown returned")
+	}
+}
+
+// slowWriter takes a millisecond over each write and drops what it is given.
+// It closes firstWrite at the first write.
+type slowWriter struct {
+	firstWrite chan struct{}
+	once       sync.Once
+}
+
+func (w *slowWriter) Write(p []byte) (int, error) {
+	w.once.Do(func() { close(w.firstWrite) })
+	time.Sleep(time.Millisecond)
+
+	return len(p), nil
+}
+
 // TestPrefixHandlerAppliesAPathWithoutAnOriginToTheRoutingTable hands the
 // prefix handler announcements whose AS path gives no origin. One whose path
 // is empty or holds AS 0 removes the peer's route, as a withdrawal does; one
@@ -199,8 +554,9 @@ func TestPrefixHandlerKeepsThePathOfAPathEndingInASet(t *testing.T) {
 	}
 }

-// checkTableCases hands the messages of each case to a new prefix handler and
-// checks its routing table right after, with no flush.
+// checkTableCases hands the messages of each case to a new prefix handler. It
+// checks the handler's routing table once the handler's PeersDown calls have
+// returned, with no flush.
 func checkTableCases(t *testing.T, tests []tableCase) {
 	t.Helper()

@@ -213,17 +569,28 @@ func checkTableCases(t *testing.T, tests []tableCase) {
 				h.HandleMessage(msg)
 			}

-			for prefix, want := range tt.want {
-				got := tableOrigins(h.table, prefix)
-				if !reflect.DeepEqual(got, want) {
-					t.Errorf("peers of %s by origin AS = %v, want %v",
-						prefix, got, want)
-				}
-			}
+			h.peerDowns.Wait()
+			checkTableOrigins(t, h.table, tt.want)
 		})
 	}
 }

+// checkTableOrigins checks, for each prefix in want, the peers that carry it
+// in table with each origin AS.
+func checkTableOrigins(
+	t *testing.T, table *routetable.Table, want map[string]map[int][]string,
+) {
+	t.Helper()
+
+	for prefix, wantOrigins := range want {
+		got := tableOrigins(table, prefix)
+		if !reflect.DeepEqual(got, wantOrigins) {
+			t.Errorf("peers of %s by origin AS = %v, want %v",
+				prefix, got, wantOrigins)
+		}
+	}
+}
+
 // tableWritesStore is a real database that hands each write of the routing
 // table's changes to written once it is made.
 type tableWritesStore struct {
@@ -498,6 +865,7 @@ func TestARestartReadsTheRoutingTableBack(t *testing.T) {
 		h.HandleMessage(msg)
 	}

+	h.peerDowns.Wait()
 	h.flushBatch()

 	var logs bytes.Buffer
@@ -536,6 +904,7 @@ func TestARestartReadsTheRoutingTableBack(t *testing.T) {
 		restarted.HandleMessage(msg)
 	}

+	h.peerDowns.Wait()
 	restarted.Stop(t.Context())

 	read, err := db.ReadRouteTable(t.Context())
@@ -486,6 +486,7 @@ type HandlerStatsInfo struct {
 	QueueHighWaterMark int     `json:"queue_high_water_mark"`
 	ProcessedCount     uint64  `json:"processed_count"`
 	DroppedCount       uint64  `json:"dropped_count"`
+	HeldBackCount      int     `json:"held_back_count"`
 	AvgProcessTimeMs   float64 `json:"avg_process_time_ms"`
 	MinProcessTimeMs   float64 `json:"min_process_time_ms"`
 	MaxProcessTimeMs   float64 `json:"max_process_time_ms"`
@@ -570,6 +571,7 @@ func handlerStatsInfo(handlerStats []streamer.HandlerStats) []HandlerStatsInfo {
 			QueueHighWaterMark: hs.QueueHighWaterMark,
 			ProcessedCount:     hs.ProcessedCount,
 			DroppedCount:       hs.DroppedCount,
+			HeldBackCount:      hs.HeldBackCount,
 			AvgProcessTimeMs: float64(hs.AvgProcessTime.Microseconds()) /
 				microsecondsPerMillisecond,
 			MinProcessTimeMs: float64(hs.MinProcessTime.Microseconds()) /
@@ -295,6 +295,43 @@ func TestStatsAnswerCarriesChurnPerMinute(t *testing.T) {
 	}
 }

+// heldBackMessages is how many messages heldBackHandler holds back.
+const heldBackMessages = 7
+
+// heldBackHandler is a stream handler that wants no message and holds back
+// heldBackMessages messages.
+type heldBackHandler struct{}
+
+func (heldBackHandler) WantsMessage(string) bool           { return false }
+func (heldBackHandler) HandleMessage(*ristypes.RISMessage) {}
+func (heldBackHandler) QueueCapacity() int                 { return 1 }
+func (heldBackHandler) HeldBackCount() int                 { return heldBackMessages }
+
+// TestStatsAnswerGivesHowManyMessagesAHandlerHoldsBack registers a handler
+// that holds back messages. Its figures in /api/v1/stats, which the status
+// page shows, must give how many.
+func TestStatsAnswerGivesHowManyMessagesAHandlerHoldsBack(t *testing.T) {
+	t.Parallel()
+
+	s := newServerWithTestRoutes(t)
+	s.streamer.RegisterHandler(heldBackHandler{})
+
+	var body struct {
+		Data StatsResponse `json:"data"`
+	}
+
+	err := json.Unmarshal(get(t, s, statsPath).Body.Bytes(), &body)
+	if err != nil {
+		t.Fatalf("decoding the answer: %v", err)
+	}
+
+	stats := body.Data.HandlerStats
+	if len(stats) != 1 || stats[0].HeldBackCount != heldBackMessages {
+		t.Errorf("handler figures %+v, want one handler holding back %d "+
+			"messages", stats, heldBackMessages)
+	}
+}
+
 // fixedIntervalASNFetcher is a WHOIS fetcher that does nothing and reports
 // interval as its wait between fetches.
 type fixedIntervalASNFetcher struct {
@@ -261,7 +261,7 @@ func checkAnswerCarriesMeta(
 ) {
 	t.Helper()

-	// The values README "API v1" gives the two fields that never change.
+	// The values README "JSON API" gives the two fields that never change.
 	const (
 		wantTimeZone   = "UTC"
 		wantAPIVersion = 1
@@ -351,6 +351,10 @@ type HandlerStats struct {
 	AvgProcessTime     time.Duration
 	MinProcessTime     time.Duration
 	MaxProcessTime     time.Duration
+	// HeldBackCount is how many messages the handler holds back to apply
+	// later: what its HeldBackCount method returns, or 0 for a handler
+	// without one.
+	HeldBackCount int
 }

 // GetHandlerStats returns a snapshot of performance statistics for all registered
@@ -392,6 +396,11 @@ func (s *Streamer) GetHandlerStats() []HandlerStats {

 		info.metrics.mu.Unlock()

+		holder, holdsBack := info.handler.(interface{ HeldBackCount() int })
+		if holdsBack {
+			hs.HeldBackCount = holder.HeldBackCount()
+		}
+
 		stats = append(stats, hs)
 	}

@@ -541,6 +541,10 @@
                        <span class="metric-label">Dropped</span>
                        <span class="metric-value ${handler.dropped_count > 0 ? 'disconnected' : ''}">${formatNumber(handler.dropped_count)}</span>
                    </div>
+                    <div class="metric">
+                        <span class="metric-label">Held Back</span>
+                        <span class="metric-value">${formatNumber(handler.held_back_count)}</span>
+                    </div>
                    <div class="metric">
                        <span class="metric-label">Avg Time</span>
                        <span class="metric-value">${formatProcessingTime(handler.avg_process_time_ms)}</span>
Author	SHA1	Message	Date
clawbot	742e75914c	Rewrite the README sentence by sentence (closes #157 ) check / check (push) Waiting to run Details The README is rewritten from scratch against the prose rules of #157: every sentence under about 30 words, lists as bullets, every technical term defined where it first appears, and every statement checked against the code on next. It leads with what RouteWatch is and how to run it, then the pages, the API and the blocklists, then the settings, memory and upaas, and last the design and the development workflow. The dated entry goes into TODO.md. Model: fable-5-1	2026-11-03 00:10:08 +01:00
clawbot	37cecedc5b	Rewrite TODO.md sentence by sentence (part of #157 ) check / check (push) Canceled after 0s Details Every sentence of TODO.md is rewritten from scratch against the rules of #157: about 30 words at most, one idea each, subject and verb early, identifiers in backticks. Status and Next Step describe the repo as the tracker shows it now. Every Completed Steps entry keeps its date, its facts and its issue reference, checked against the commit it names. The Workflow section keeps its meaning. The entry for this rewrite is added. Model: fable-5-1	2026-11-02 23:44:09 +01:00
clawbot	e5afd94a39	Take every down peer out of the table in one walk (closes #225 ) check / check (push) Canceled after 0s Details The prefix handler ran one PeerDown per peer, one after another. When the sessions of several peers went down together, their walks queued up. A returning full-table peer's messages stayed held back while the walks ahead of its own ran, and could reach the limit of 20,000. The table's PeersDown now takes several peers out of every prefix in one walk. One walk runs at a time. The next one takes every peer whose session went down since the previous one began. The doc of maxHeldBackMessages says how long a peer's messages are held back. The limit is now 150,000 messages, about 150 MiB. The status page shows how many messages each handler holds back. Model: opus-5-5	2026-11-02 23:10:09 +01:00
clawbot	9bd0e91a3b	Let the lock go for as long as it was held during Overview's walk (closes #226 ) check / check (push) Canceled after 0s Details The home page's cards are worked out once a minute by Overview, which walks every prefix of the routing table under the table's read lock. After each batch of 10,000 prefixes, the walk let the lock go and took it back at once. The prefix handler, waiting for the write lock, then got in only once per batch. During a walk, its queue could fill, and the streamer then dropped updates for it. The walk now lets the lock go for as long as it held the lock for the batch, as PeerDown does. A test applies another peer's 1,000 announcements while Overview walks a table with more prefixes than five of the walk's batches. Model: opus-5-5	2026-11-02 08:00:00 +01:00
clawbot	d66c59ef07	Lengthen the WHOIS fetcher's wait after a skipped lookup (closes #222 ) check / check (push) Canceled after 0s Details A lookup whose RIR is paused is skipped. The skip left the fetcher's wait as it was. Each lookup asks IANA before it finds its RIR paused. So while most stale ASes belonged to a paused RIR, the fetcher could ask IANA every second. Like a failure, a skipped lookup now makes the wait 1.5 times as long, up to one minute. The skip is still not counted as a failure, so the status page's failure figures leave it out. Model: opus-5-5	2026-11-02 03:59:47 +01:00
clawbot	26d939ad72	Keep taking messages while a peer's session goes down (closes #216 ) check / check (push) Canceled after 0s Details The table's PeerDown visits every prefix under the write lock, which takes over a second on a full table. The prefix handler called it inline, so its queue filled and the streamer dropped updates. PeerDown now holds the lock for 10,000 prefixes at a time, then lets the lock go for as long again. The handler runs PeerDown on a separate goroutine, one peer at a time. The handler holds back the down peer's later messages until that PeerDown returns. Then the handler applies them in order, one at a time, and takes new messages in between. It holds back at most 20,000 messages. Stop waits for all of this before its last flush. Model: opus-5-5	2026-11-02 03:27:10 +01:00
clawbot	df15e2b2cd	Pause a registry's WHOIS server after it refuses a query (closes #218 ) check / check (push) Canceled after 0s Details The fetcher kept one interval for every registry, so a registry that refused a query was asked again within seconds. RIPE blocked the test host's address that way. The WHOIS client now pauses an RIR's or NIC.br's server for an hour after the server refuses a query. A refused or reset connection is a refusal, and so is an %ERROR:201: or %ERROR:202: line. Lookups at the other servers go on. A lookup whose RIR is paused leaves the AS stale, and counts as neither a success nor a failure. IANA is never paused, because a pause of IANA would stop every lookup. NIC.br's hour-long skip after its over-limit answer is now the same pause. Model: opus-5-5	2026-11-02 02:59:57 +01:00
clawbot	6b004dfbc3	Keep one entry per AS in the AS handler's batch (closes #217 ) check / check (push) Canceled after 0s Details HandleMessage added one entry to the batch for every AS of every path, and waited for the write in progress once the batch held 300,000. In a burst of the feed its queue then filled, and the streamer dropped messages. The batch is now a map from AS number to the earliest and the latest time of its updates. It holds one entry per AS, so it no longer grows with the feed's rate. HandleMessage never waits for a write. asnBatchSize now counts ASes. Stop logs the entries of the batch being written and of the next batch under "batch_entries". An AS in both counts twice. Model: opus-5-5	2026-11-02 02:10:17 +01:00