1595478 - FF 68 and 69 frequently hang with ~30% CPU, "waiting for network I/O to finish"

Status: RESOLVED WORKSFORME

(Core :: Networking, defect, P3)

Description

[[e-mail]]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:69.0) Gecko/20100101 Firefox/69.0

Steps to reproduce:

Routine FF use with between single digits and hundreds of tabs, on Win10 Enterprise, x86-64 platform. Simple Tab Groups, uBlock Origin, Brief, Pinboard, User Agent Switcher, Cisco WebEx, Greasemonkey, Push to Kindle present. HW acceleration has been tried on and off without any effect. Places.sqlite has been integrity checked and vacuumed.

Actual results:

FF hangs frequently (every 5 to 20 minutes) and does not recover (for up to 5 mins). Task Manager shows 5 to 8 FF threads, normal levels of resource usage (ie not memory leaking), and always the last thread listed "not responding". The Windows "analyze wait chain" function reports this thread is "waiting for network I/O to finish". Networking element may be interesting - hangs are less frequent on our enterprise LAN than at home. If you kill the thread, FF restarts immediately without showing about:sessionrestore.

Expected results:

Not hanging every 5 minutes.

Comment 1

[[e-mail]]

This is really odd. Yesterday, on my home network, there were dozens of hangs. Today, on the office network, precisely one all day.

Comment 2

[Pablo]

Hi
Im unable to replicate on my machine with windows10 64 bit using firefox release 70.0.1. I have been opening many tabs but its difficult to replicate. How many tabs do you have open ?

Can you share with us the information that is showing firefox when you type " about:crashes " on the url bar?

Also please download the latest Firefox Nightly release from here: https://nightly.mozilla.org/ and retest the problem.

If you still have the issue please create a new profile, you have the steps here:https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles?redirectlocale=en-US&redirectslug=Managing-profiles#w_starting-the-profile-manager

Lastly test if the issue is reproducible in safe mode, here is a link that can help you:
https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode

Regards
Pablo

Comment 3

[[e-mail]]

About:crashes shows "no crash reports have been submitted"

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The priority flag is not set for this bug.
:jimm, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 5

[[e-mail]]

Weird update: the problem has gone away? I wonder if my adblocker got a list update and started killing something it wasn't previously blocking...

Comment 6

[Michal Novotny [:michal]]

Closing as WFM for now. Feel free to reopen the bug if it appears again.