1449862 - Check for available port each time before starting binary

Status: RESOLVED FIXED

(Remote Protocol :: Marionette, enhancement, P1)

Description

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Currently we only check if port 2828 is available when initializing Marionette:

https://dxr.mozilla.org/mozilla-central/rev/a456475502b80a1264642d9eaee9394a8fad8315/testing/marionette/client/marionette_driver/marionette.py#618-620

This is racy and can lead to side-effects like I have seen on bug 1400819 when using non in_app `restart()` and `quit()` calls, because for the next session this check is no longer performed and accidentally left-over instances of Firefox would still claim that port.

Result is that we would continue to run our tests in the other process but not the currently started one.

To prevent things like that we should really do this check each time the process gets started via `start_binary()`.

Comment 1

[Henrik Skupin [:whimboo][⌚️UTC+1]]

Attachment: Bug 1449862 - [marionette] Check for available port each time before starting binary.

To prevent race conditions when a formerly started Firefox instance is
still claiming the port of the server socket, the port availability has
to be checked each time before the binary gets started. Otherwise the
client could accidentally connect to the wrong process, and also would
run the remaining tests with it.

Review commit: https://reviewboard.mozilla.org/r/232442/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/232442/

Comment 2

[Andreas Tolfsen ❲:ato❳]

Comment on attachment 8963500 [details]
Bug 1449862 - [marionette] Check for available port each time before starting binary.

https://reviewboard.mozilla.org/r/232442/#review237854

It’s terrible we are still stuck with this type of port allocation
polling.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0d99bcacaf32
[marionette] Check for available port each time before starting binary. r=ato

Comment 4

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/0d99bcacaf32