| 30 Jan 2026 |
 Randy Eckenrode | Overriding the stdenv used by Rust is extremely annoying. It was one of the motivating reasons for how the new SDK pattern ended up as it did. | 12:48:58 |
 Tristan Ross | Yeah, I'm using crane so it's at least easier to deal with some of these things | 12:50:02 |
|  matthewcroughan @fosdem changed their display name from matthewcroughan to matthewcroughan @fosdem. | 13:32:15 |
|  @brianhicks:matrix.org left the room. | 19:53:50 |
 Ihar Hrachyshka | Austin Horstman: in my local run, the biggest gap between messages in firefox build is:
[2026-01-29 22:40:51] firefox-unwrapped> make[3]: Leaving directory '/nix/var/nix/builds/nix-84991-1567875916/firefox-147.0.2/objdir/media/ffvpx/libavcodec'
[2026-01-29 23:22:13] firefox-unwrapped> /nix/var/nix/builds/nix-84991-1567875916/mozbuild/srcdirs/firefox-147.0.2-a7aea0efcd6d/_virtualenvs/build/bin/python -m mozbuild.action.check_binary ../../../dist/bin/XUL
42 minutes of silence :)
| 23:45:50 |
| Ihar Hrachyshka | and this is right after "libavcodec" (we saw it as last message in some timed out runs) | 23:46:46 |
| Ihar Hrachyshka | brb adding a background noise generator that would print silly jokes once every 5 mins while firefox is doing lto... | 23:47:53 |
| Ihar Hrachyshka | the default hydra setting for silence is 2h; we are bumping it in meta.maxSilent to 4h but maybe it's ignored somehow. on a slower machine, it's probably not out of the ordinary for something taking 40 mins on a dedicated m4 machine to take 2h+ instead. | 23:52:50 |
|  Atakan Dulker joined the room. | 23:53:12 |
| 31 Jan 2026 |
 hexa | is it? if you think so file an issue on the hydra repo | 00:25:52 |
| hexa | the question I have is if we are making a mistake by configuring max-silent-time on nix on the builders instead | 00:27:31 |
| hexa | and hydra can't override that | 00:27:35 |
| hexa | frankly not sure what takes precedence | 00:27:49 |
 Austin Horstman | yeah, we were talking yesterday about trying to figure out the whole chain of defaults/overrides/priorities and how to resolve our issue lol | 00:28:38 |
| Austin Horstman | how long did your run take when you built it by itself? | 00:34:20 |
| Ihar Hrachyshka | $ head -n 1 build.log ; tail -n 1 build.log
[2026-01-29 21:23:19] checking outputs of '/nix/store/bv412dcrijv03g2ww78g9fbwa4gggblf-firefox-unwrapped-147.0.2.drv'...
[2026-01-29 23:25:04] error: derivation '/nix/store/bv412dcrijv03g2ww78g9fbwa4gggblf-firefox-unwrapped-147.0.2.drv' may not be deterministic: output '/nix/store/6d74j4kykgaskhbkc1z21jycmqzzpb0m-firefox-unwrapped-147.0.2' differs
| 00:50:59 |
| Austin Horstman | hmm that seems super quick | 00:55:57 |
| Austin Horstman | i went to go test the build time real quick | 00:57:11 |
| Austin Horstman | 
Download image.png | 00:57:12 |
| Ihar Hrachyshka | it's a m4 mac mini with 32gb ram | 00:57:14 |
| Austin Horstman | what do you have nix configured for cores/max-jobs etc | 00:57:35 |
| Austin Horstman | cuz i have a m4 max 64gb and mine took much longer last time... | 00:58:04 |
| Austin Horstman | but i always did it as part of a config build | 00:58:25 |
| Ihar Hrachyshka | $ cat /etc/nix/nix.conf | grep 'core\|max'
cores = 0
max-jobs = 5
it's a 10core machine
| 00:58:43 |
| Austin Horstman | Hmm wonder if i'm hurting myself by setting cores.. | 00:59:20 |
| hexa | yeah, that's easily bigger than all the builders we have | 01:04:08 |
| Ihar Hrachyshka | in infra config, we have max-silent-time = 7200; # 2h for all macs.
the PR that added support for passing these overrides from untrusted clients is: https://github.com/NixOS/nix/pull/7079
which has been there for a long time...
$ git tag --contains 6e049ae607b53eba3c9c6bed260a0b39a3f73a70 | sort | head -n 1
2.12.0
| 01:15:47 |
| Ihar Hrachyshka | https://github.com/NixOS/nix/blob/77b6b01b727f0cd1324e431a32a8854768b957ef/src/nix/nix-store/nix-store.cc#L903
so Hydra calls to remote via ssh, runs nix-store --serve there, nix-store then calls to local nix-daemon. When it does this call, apparently it doesn't propagate the settings? | 01:38:31 |
| Ihar Hrachyshka | actually, second rebuild of firefox took even quicker...
$ head -n 1 build.log ; tail -n 1 build.log
[2026-01-30 19:53:47] warning: Git tree '/Users/ihrachyshka/src/nixpkgs/ff-timeouts' is dirty
[2026-01-30 20:39:10] firefox-unwrapped (post)> ✅ All done! (2 already cached, 19 in upstream)
| 02:10:40 |
| Ihar Hrachyshka | ah I see. the previous 2h result was on ... macbook air. the second one that completed in 46 mins is the actual mac mini m4 run. | 02:14:02 |
