STR: Load treeherder.mozilla.org on the latest nightly w/ e10s enabled. Run profile. Stop profiling. Firefox will beachball indefinitely. Other sites do not seem to do this.

Should clarify that I reproduced this specifically on Mac, haven't tried on Linux or Windows.

Just talked to wlach, and he said that this was from the Developer Tools Profiler.

I can easily reproduce this on a treeherder page. STR: 1) Visit https://treeherder.mozilla.org/#/jobs?repo=mozilla-inbound 2) Open the Developer Tools for the page, and choose the Performance tab 3) Click on the stopwatch in the top left to start profiling 4) Scroll around for a few seconds, and then hit "Stop Profiling" to gather the profile 5) Watch your machine get hosed ER: I should eventually get a profile, or at least some kind of feedback that a profile is being gathered. AR: Main-process beach-balling, and the whole browser becomes unresponsive. I only tested this with e10s enabled, but I can't imagine that this would be any more performant with it disabled.

cc'ing :BenWa - I suspect that this might be back-end related, though I can't say for sure. Still, I felt that since this was reproduced via the Developer Tools Performance tab that this is the right component for now. I'll note that in the STR in comment 3, that after a few minutes, I saw a few things start to render (albeit in a very janky way) - like, mouse events were being responded to, but they were few and far between. So maybe what we've got here is bad performance with our Performance tooling. :/

I know fitzgen was using treeherder to dogfood the performance tools. In the gear options in the upper right corner, what options are enabled? There are a few of them that can be very unperformant (mostly related to recording memory, and allocations can get a little slow right now). I suspect it's generating a lot of markers and the waterfall view hangs on rendering a large amount (a few bugs open for this, but bug 1152441 is one of them)

Here are the settings enabled when the hang occurs. Still reproducible on the latest Nightly.

Here's a cleopatra profile of the browser hanging while it's calculating stuff: http://people.mozilla.org/~bgirard/cleopatra/#report=363caa9ccea8c7097c4a331a2a32360e91708529&selection=0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55 For whatever reason it seems to have sped up a little bit from before, though the browser still pauses and the result is basically unusable.

This is really weird, it looks like most of the functions aren't properly symbolicated in that profile, which unfortunately makes it mostly unusable. Will, sorry to bug you again, but would you mind profiling once more with instruments?

(In reply to Nick Fitzgerald [:fitzgen][:nf] from comment #8) > This is really weird, it looks like most of the functions aren't properly > symbolicated in that profile, which unfortunately makes it mostly unusable. > > Will, sorry to bug you again, but would you mind profiling once more with > instruments? Told this wasn't necessary on irc.

Triaging. Filter on ADRENOCORTICOTROPIC (yes).

This works now, fwiw. No idea why, don't care. :)