JSONLogger: rate-limit resProgress per activity - #16369
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copyPaths() reports progress for every NAR chunk and JSONLogger wrote a line for each. In build-remote the log fd is a pipe that nix-daemon only drains between goal iterations, so the hook blocked in JSONLogger::write mid-NAR while holding the upload lock, stalling all remote builds to that machine. This is fixed by emitting resProgress at most every 100ms per activity, except for the final update (done >= expected). This commit just removes the trigger but we might want to fix the underlying issue later in a more prinicipaled way that removes the hook's log output completely from the tryBuildHook logic, since the pipe theoretically still can get full. However overall it seems reasonable to rate limit this event anyhow to reduce load on nix clients and this fix might be an easy backport.
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One of the issues I debugged live on a builder as it happened, so a bit hard to reproduce otherwise.
copyPaths() reports progress for every NAR chunk and JSONLogger wrote a line for each. In build-remote the log fd is a pipe that nix-daemon only drains between goal iterations, so the hook blocked in JSONLogger::write mid-NAR while holding the upload lock, stalling all remote builds to that machine.
This is fixed by emitting resProgress at most every 100ms per activity, except for the final update (done >= expected).
This commit just removes the trigger but we might want to fix the underlying issue later in a more principled way that removes the hook's log output back-pressure completely from the tryBuildHook logic, since the pipe theoretically still can get full.
However overall it seems reasonable to rate limit this event anyhow to reduce load on nix clients and this fix might be an easy backport.