1229512 - Recording performance of Fennec nightly (or local fennec build) causes Fennec to hang or crash

Status: RESOLVED WONTFIX

(DevTools :: Performance Tools (Profiler/Timeline), defect, P3)

Description

[Kartikaya Gupta (email:[e-mail])]

Attachment: traces.txt

STR:

- Install Fennec nightly on a device (I have a nexus 4). Start it up and enable remote debugging. Load a page.
- On desktop (I have OS X) nightly, start WebIDE and connect to the device.
- Pick the tab with the page loaded and switch to the Performance pane in the devtools.
- Start recording

ER:
- You can do stuff in Fennec and have the devtools profiler show you where CPU time is being spent

AR:
- Fennec hangs. Doing any UI interaction has no effect, and the ANR warning pops in 5 seconds. The devtools profiler *seems* to be getting data but I can't tell if it's valid or garbage. If I kill fennec on the device the profiler just keeps going like nothing happened.

I got the /data/anr/traces.txt from the device and am attaching it although I don't see anything in there that would explain this behaviour.

Comment 1

[Benoit Girard (:BenWa)]

The trace doesn't seem to include Fennec? Can't we get a gdb/jimdb all threads backtrace?

If you're trying to debug a platform problem you're going to want to use the platform profiler front-end instead of the WebIDE front end which wont collect native stacks.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

(In reply to Benoit Girard (:BenWa) from comment #1)
> The trace doesn't seem to include Fennec? Can't we get a gdb/jimdb all
> threads backtrace?

I'll do that tomorrow.

> If you're trying to debug a platform problem you're going to want to use the
> platform profiler front-end instead of the WebIDE front end which wont
> collect native stacks.

I tried that, but the gecko profiler add-on wasn't connecting to the device. No idea why.

Comment 3

[Kartikaya Gupta (email:[e-mail])]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #2)
> (In reply to Benoit Girard (:BenWa) from comment #1)
> > The trace doesn't seem to include Fennec? Can't we get a gdb/jimdb all
> > threads backtrace?
> 
> I'll do that tomorrow.

So.. doing it with gdb attached seems to work, sort of. Fennec crashes a lot though, and I couldn't get an actual useful profile. Crash reports at
https://crash-stats.mozilla.com/report/index/985bac40-88e9-49d3-a036-0e34c2151202
https://crash-stats.mozilla.com/report/index/da862966-86c7-4ed6-a787-4bbaf2151202

> > If you're trying to debug a platform problem you're going to want to use the
> > platform profiler front-end instead of the WebIDE front end which wont
> > collect native stacks.
> 
> I tried that, but the gecko profiler add-on wasn't connecting to the device.
> No idea why.

This worked when I tried it again today. I don't know what changed, I think rebooting the device may have helped.

Comment 4

[Victor Porof [:vporof][:vp]]

Triaging. Filter on ADRENOCORTICOTROPIC (yes).

Comment 5

[Greg Tatum [:gregtatum]]

This is a really outdated crash with no clear STR. I'm closing for now.