1626132 - Ghost-Windows from reddit

Status: NEW

(Core :: Performance, defect, P2)

Description

[Ted Campbell [:tcampbell]]

Basic information

Steps to Reproduce:
Visit a Slack instance migrated to new design (so not the Mozilla one).
Idle and type in message box.

Expected Results:
Smooth typing

Actual Results:
3 second pauses

---

More information

Screenshot: (if relevant, please attach a screenshot or screencast to this bug report)

Profile URL: https://bit.ly/2ylSnPn

Basic systems configuration:

OS version: Windows 10

GPU model: Intel

Number of cores: 4/8

Amount of memory (RAM): 16 GB

Thanks so much for your help.

Comment 1

[Andrew McCreight [:mccr8]]

You'll also want an about:memory report. Maybe a CC log, too, because that records what the CC is actually looking at. Skimming the profile, it looks like most of the time is being spent traversing JS.

Comment 2

[Andrew McCreight [:mccr8]]

(The CC log will contain lots of data in memory, so you may not want to share it publicly.)

Comment 3

[Ted Campbell [:tcampbell]]

Looking at my about:memory, I have a number of very large ghost windows in that content process.

Comment 4

[Andrew McCreight [:mccr8]]

Ok. That means we're leaking windows, which causes the cycle collector to be very slow. Somebody who can reproduce it will have to debug the memory leak.

Comment 5

[Emilio Cobos Álvarez (:emilio)]

For how long did you idle to see this out of curiosity?

Also, I think there's a slack instance with the new design everyone can join in https://w3ccommunity.slack.com/.

Comment 6

[Ted Campbell [:tcampbell]]

Restarting did fix things. I tried to capture a GC/CC log and it actually hung in the parent process while infinitely trying to trace. I couldn't get WinDBG to behave. I have the partial CC/GC logs which I can try getting into.

This session was probably a week old. The ghost windows were mostly reddit.

Comment 7

[Andrew McCreight [:mccr8]]

Do you have any Reddit-related extensions installed? Do you use the old or new layout for Reddit? I use Reddit a fair amount, but I haven't noticed any big slowdown, but with Fission processes get created and killed more frequently.

Comment 8

[Ted Campbell [:tcampbell]]

No extensions except Containers and Profiler. Was on new-reddit. I've not run into this before and this session wasn't really different than what I normally do. I guess running nightly for more than 48hr is unusual for me though.

Comment 9

[Ted Campbell [:tcampbell]]

Actually, that is incorrect. BuildID from profile says this was only running for a day when it happened. I'll keep an eye on if I see ghost windows again.

Comment 10

[Ted Campbell [:tcampbell]]

This doesn't seem to be a slack issue, but rather the content process had ghost-windows in it. As a result, I'm renaming this bug and clearing [wfh].

Perhaps this should be closed as WORKSFORME. I'm not sure how we deal with unreproducible ghost-windows.

Comment 11

[Andrew McCreight [:mccr8]]

If this happens again, please get GC/CC logs using about:memory. Then you can run find_roots.py and maybe get some information on what is keeping the Reddit windows alive.

Comment 12

[Andrew McCreight [:mccr8]]

Bug 1628664 is another bug about ghost windows on Reddit.

Comment 13

[Firefox Bug Husbandry Bot]

Because this bug's Severity has not been changed from the default since it was filed, and it's Priority is -- (Backlog,) indicating it has has not been previously triaged, the bug's Severity is being updated to -- (default, untriaged.)