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Status: Assigned
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EstimatedDays: ----
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Pri: 3
Type: Bug

Blocked on:
issue 695864



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goma build with a high -j value spawns hundreds of python processes for bindings

Project Member Reported by esprehn@chromium.org, Sep 30 2016

Issue description


This is on my Mac Pro 2013 (Trashcan).

What steps will reproduce the problem?
(1) ninja -C out/Release content_shell -j600

What is the expected output?

Should only start {number of cores} local jobs, in my case 24.

What do you see instead?

600 python jobs start, this makes the bindings step take ages (5-10m) by being bottle necked on the disk throughput. If I do ninja -C ... -j 24 for the bindings step it only takes a few seconds instead of many minutes.
 
Actually this is probably local CPU contention, but in either case we should never start the full -j number of local jobs for a goma build if it's way over the CPU count.
Cc: yukishiino@chromium.org peria@chromium.org bashi@chromium.org
peria@: Is this related to your change that has increased # of aggregated files?

Comment 3 by ukai@chromium.org, Oct 3 2016

better to specify pool for binding rules in ninja?
https://ninja-build.org/manual.html#ref_pool

Comment 4 by peria@chromium.org, Oct 3 2016

Re #2;
Yes, http://crrev.com/417935, which started to compile each generated file in parallel, could trigger this issue, but the root issue is in ninja and goma, as commented in #0.

Ukai-san, can't goma limit the number of local-fallback processes?

Comment 5 by ukai@chromium.org, Oct 3 2016

I think binding generator doesn't run under gomacc, so it's out of control of goma.

Comment 6 by peria@chromium.org, Oct 3 2016

Ah, I see.  This issue is not in compiling C++ files, but in generating them.
Then, my CL in #4 is not related, and this issue should be existing for long.
Owner: peria@chromium.org
Status: Assigned (was: Untriaged)

Comment 8 by peria@chromium.org, Mar 2 2017

Blockedon: 695864

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