1280636 - subprocess busy-polls the sentinel fd if it is closed unexpectedly

Status: RESOLVED FIXED

(Toolkit :: Async Tooling, defect)

Description

[Andrew Swan [:aswan]]

I don't have an isolated reproduction, but I can try to create one if its helpful.
But I think the sequence that triggers this bug occurs when we have pending reads/writes and the subprocess exits.  If the first indication we get is POLLNVAL on the stdin file descriptor, that triggers Pipe.onError() which calls process.wait() which calls waitpid() which returns with an exit code right away which causes the sentintel fd to be closed.
But then the process object remains remains in the io.processes map and continues to return non-zero pollEvents, so we just keep polling and keep triggering errors.

I think the fix is as simple as calling updatePollFds() from Process.onError()

Comment 1

[Andrew Swan [:aswan]]

Attachment: Bug 1280636 Call updatePollFds() on error on sentinel fd

Review commit: https://reviewboard.mozilla.org/r/59504/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/59504/

Comment 2

[Kris Maglione [:kmag]]

Comment on attachment 8763234 [details]
Bug 1280636 Call updatePollFds() on error on sentinel fd

https://reviewboard.mozilla.org/r/59504/#review56618

::: toolkit/modules/subprocess/subprocess_worker_unix.js:411
(Diff revision 1)
>     *
>     * @see pollEvents
>     */
>    onError() {
>      this.wait();
> +    io.updatePollFds();

I think it would make more sense to put this after `this.fd.dispose()` in `wait()`.

Comment 3

[Andrew Swan [:aswan]]

Comment on attachment 8763234 [details]
Bug 1280636 Call updatePollFds() on error on sentinel fd

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/59504/diff/1-2/

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/dc5c9230e418
Call updatePollFds() on error on sentinel fd r=kmag

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/dc5c9230e418