2036987 - Disable process output storage to reduce memory pressure during test runs

Status: RESOLVED FIXED

(Testing :: Marionette Client and Harness, task, P3)

Description

[Henrik Skupin [:whimboo][⌚️UTC+2]]

The ProcessHandler's storeOutput flag causes all Firefox process output to be accumulated in an unbounded list for the lifetime of each process. With verbose logging enabled (-vv / Trace level), this can grow to tens of thousands of entries over a test run. The accumulated strings are
never consumed by the Marionette runner.

Disabling storeOutput avoids the memory growth and reduces GC pressure, which could contribute to the stdout pipe stalling under load on CI causing test failures like bug 1970481 or missing log output as noted on bug 1989904.

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+2]]

Attachment: Bug 2036987 - [marionette] Disable process output storage to reduce memory pressure during test runs.

The ProcessHandler's storeOutput flag causes all Firefox process output
to be accumulated in an unbounded list for the lifetime of each process.
With verbose logging enabled (-vv / Trace level), this can grow to tens
of thousands of entries over a test run. The accumulated strings are
never consumed by the Marionette runner — output is already streamed
to stdout via StreamOutput.

Disabling storeOutput avoids the memory growth and reduces GC pressure,
which could contribute to the stdout pipe stalling under load on CI.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/841f2f288913
https://hg.mozilla.org/integration/autoland/rev/c9c60626d7ec
[marionette] Disable process output storage to reduce memory pressure during test runs. r=jdescottes

Comment 3

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/c9c60626d7ec