1491816 - deal with unresponsive content processes in ChromeUtils.requestPerformanceMetrics()

Status: RESOLVED FIXED

(Toolkit :: Performance Monitoring, enhancement)

Description

[Tarek Ziadé (:tarek)]

Right now a call to ChromeUtils.requestPerformanceMetrics() waits for all content process to return their data. But if one is unresponsive (slow script, etc.) it will hold the promise.

We need to deal with this issue, and if possible report back on which content process is acting out, so about:performance can use that information

Comment 1

[Tarek Ziadé (:tarek)]

Attachment: Bug 1491816 - deal with unresponsive content processes in ChromeUtils.requestPerformanceMetrics() - r?baku

Adds a timout that will resolve the promise to return even if we did not get an answer from
all children.

MozReview-Commit-ID: FFLwAUkkYos

Comment 2

[Tarek Ziadé (:tarek)]

Florian, unfortunately I have not found a good mechanism in IPC to mock the delay in content process or workers.

Could you give us your STRs this issue so we can manually verify that the timeout is correctly triggered ?

Thanks

Comment 3

[Florian Quèze [:florian]]

(In reply to Tarek Ziadé (:tarek) from comment #2)

> Could you give us your STRs this issue so we can manually verify that the
> timeout is correctly triggered ?

A page containing this piece of JS should make its content process unresponsive:

function fn() {
  let start = Date.now();
  while (Date.now() - start < 5000)
    ; // do nothing
  setTimeout(fn, 0);
}
fn();

It should be possible to cover this with an automated test, right?

Comment 4

[Tarek Ziadé (:tarek)]

Before commenting here I tried a similar test with workers but could not get it to work. 

Your example seems to work though, thanks a lot! working on adding that

Comment 5

[Tarek Ziadé (:tarek)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=7807bede28e7ea9babd4e6ab04e9f2bc74dfbc75

Comment 6

[Tarek Ziadé (:tarek)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=2a63021f697708440de6141b3b7f66d34f29756c

Comment 7

[Tarek Ziadé (:tarek)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=6b56878fc3146a427b6b7a1047c83d4dddd6940f

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8958a60dd824
deal with unresponsive content processes in ChromeUtils.requestPerformanceMetrics() - r=baku

Comment 9

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/8958a60dd824