fix(web): scale web heap limit to container memory (#1569)

* fix(web): scale web heap limit to container memory

Node's default old-space limit caps at ~4GiB regardless of how much memory
the container actually has. On larger deployments the web process fills that
ceiling and V8 falls into back-to-back full mark-compact collections, which
block the event loop for seconds at a time and slow every route at once.

Set --max-old-space-size-percentage on the web program so the heap scales
with the container's memory limit. Node reads the cgroup limit, so this is
proportional on every deployment size. Scoped to [program:web] via
supervisord so the backend and zoekt are unaffected.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* docs: add changelog entry for web heap limit fix

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* fix(web): use 50% rather than 75% for the web heap limit

At a 16GiB limit this gives the web process an 8384MiB ceiling (up from
4288MiB), which still resolves the GC thrash while leaving roughly 7.7GiB for
page cache. zoekt currently uses ~5.8GiB of file cache for its EFS-backed
index, and 75% would have squeezed that to ~3.6GiB.

50% also matches Node's own default curve below the ~4GiB cap, so deployments
at or under 8GiB are unaffected by this change.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* Remove comment in supervisord configuration

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: brendan-kellam

CHANGELOG.md

@@ -10,6 +10,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Added a manually triggered cloud image release workflow for isolated internal deployments. [#1566](https://github.com/sourcebot-dev/sourcebot/pull/1566)
 
+### Fixed
+- Fixed the web process being capped at a ~4GiB heap regardless of how much memory the container has, which caused multi-second garbage collection pauses on larger deployments. [#1569](https://github.com/sourcebot-dev/sourcebot/pull/1569)
+
 ## [5.1.6] - 2026-08-10
 
 ### Added

supervisord.conf

@@ -15,6 +15,7 @@ redirect_stderr=true
 
 [program:web]
 command=./prefix-output.sh node packages/web/server.js
+environment=NODE_OPTIONS="--max-old-space-size-percentage=50"
 priority=20
 autostart=true
 autorestart=true
@@ -31,4 +32,4 @@ autorestart=true
 startretries=3
 stdout_logfile=/dev/fd/1
 stdout_logfile_maxbytes=0
-redirect_stderr=true
+redirect_stderr=true