1989043 - Reduce the number of parallel xpcshell tests on Windows to twice the core count

Status: RESOLVED FIXED

(Testing :: XPCShell Harness, task)

Description

[Florian Quèze [:florian]]

In bug 1986407 I removed all the Windows specific limits to how many xpcshell tests we run in parallel. It seems that was a bit excessive as now the machines are under high load.

Here are some resource usage profiles:

• The machines have 8 logical cores
• Current state: 32 tests in parallel (+ 3 wasted cores by unrelated processes; getting fixed in the next Windows VM image) https://share.firefox.dev/4mhuxq3
• 32 tests in parallel (no more wasted cores, using the alpha fixed VMs): https://share.firefox.dev/4n1qH5G
• 12 tests in parallel: https://share.firefox.dev/48m4nzc (no longer at 100% CPU use)
• 16 tests in parallel: https://share.firefox.dev/46FPiHo (I think going ahead with this would be reasonable)

In these profiles, look for the new "Sampling Interval" track that indicates how long it took for resourcemonitor.py's 100ms timer to be fired. That's a good proxy for how much load the machine is receiving.

Whether we should include that "Sampling Interval" track in the resource monitor by default to make future similar troubleshooting easier is an open question. I'm leaning towards 'yes'.

Comment 1

[Florian Quèze [:florian]]

Attachment: Bug 1989043 - Reduce the number of parallel xpcshell tests on Windows to twice the core count, r=jmaher.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/1d3bfe7467e2
https://hg.mozilla.org/integration/autoland/rev/7243bd713cbc
Reduce the number of parallel xpcshell tests on Windows to twice the core count, r=jmaher.

Comment 3

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/7243bd713cbc