1679443 - Add test ensuring profiles created by background tasks are (and remain) "slim"

Status: RESOLVED FIXED

(Toolkit :: Background Tasks, task, P3)

Description

[Nick Alexander :nalexander [he/him]]

The "background task in Gecko" approach that Bug 1667276 is building out will use a temporary profile created at task runtime (and torn down as the task exits). This ticket tracks writing a test, similar to existing performance tests, that ensures that the background task mechanism itself doesn't churn the disk too much. The general idea is to:

1. keep a temporary profile from a no-op (or minimal) background task
2. enumerate the contents (after minimizing them by configuring caches and disabling functionality)
3. ensure that the test fails when the contents grow unexpectedly.

Comment 1

[Nick Alexander :nalexander [he/him]]

Attachment: Bug 1679443 - Add test ensuring profiles created by background tasks are (and remain) "slim". r?nrishel

There are a few ways that we could test this. We could use the
profiler and "File IO" markers, a la
https://searchfox.org/mozilla-central/source/browser/base/content/test/performance/browser_startup_content_mainthreadio.js.
This would profile content that is transient, which could be good or
bad -- temporary files for atomic writes would show up for example.
But in fact there are profile contents created after the profiler is
shut down (including Telemetry.ShutdownTime.txt), so this approach
isn't sufficient.

Therefore we do the simpler thing: we simply don't remove the
temporary profile directory after the background task exits.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c612daa91aec
Add test ensuring profiles created by background tasks are (and remain) "slim". r=bytesized

Comment 3

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/c612daa91aec