Measure elapsed time in phases (successful or not)

Help
1

Hello everyone.

I am looking to reliably measure the time spent in each phase while building a derivation. I am primarily interested in the buildPhase and checkPhase.

Additionally, I need to have such metrics even when a derivation fails to build.

I found this open issue 1. Do you have any other pointers?

Thanks!

3 Likes
2

The generic builder currently logs the start of each phase to Nix using a structured log message: https://github.com/NixOS/nixpkgs/blob/2c166749c9ef9440defccf94f50cc8f1a9852b3c/pkgs/stdenv/generic/setup.sh#L1377-L1379

Currently this is only used in Nix to update the progress bar, but we could use it to infer the duration of each phase. Or change showPhaseFooter (https://github.com/NixOS/nixpkgs/blob/2c166749c9ef9440defccf94f50cc8f1a9852b3c/pkgs/stdenv/generic/setup.sh#L1392) to emit a structured log message to $NIX_LOG_FD showing the duration. However, that won’t work if the phase fails.

4 Likes
3

I will into this, thank you @edolstra!

1 Like
4

nom is already using that.

1 Like