1692393 - opening link in new tab yields empty and weirdly behaving tab if child process hangs

Status: UNCONFIRMED

(Core :: DOM: Content Processes, defect, P3)

Description

[unixway.drive+moz]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:76.0) Gecko/20100101 Firefox/76.0

Steps to reproduce:

• Create new profile
• Set content process limit to 2 (or open a bunch of pages to spawn all content processes allowed)
• Open a page with a lot of links
• Find through the about:memory the pid of a process that renders that page
• Send SIGSTOP to the other content processes (simulate the hang)
• Open a bunch of links in new tabs

This can be reproduced with versions 85.0.2 and 76.0.1, and probably even earlier versions.

Actual results:

• Tabs open with empty viewport and no signs of activity
• Tabs won't load via F5 even if corresponding processes crash with the "Your tab just crashed" message
• When present, addons like URLs list would report about:blank instead of actual page URLs even though the browser itself actually renders proper link in the address bar
• When pressed Esc while address bar is in focus, the contents would reset to empty string instead of original URL
• Tabs would restore as about:blank after browser restart, with empty address bar

Comment 1

[unixway.drive+moz]

I guess there are more scenarios that can render even properly loaded pages into this weird state, however I can't reliably reproduce this rather randomly occurring problem — the only common thing I see is hanging/crashing processes in presence of hundreds of loaded tabs.

Comment 2

[Timea Cernea [:tbabos][inactive]]

Hi,
I am not particularly sure if this unexpected hang that was simulated should be supported for further investigation but as you also said this is the closest repro steps available for the random cases that you encountered.
Setting up a Component so the developers can take a look at this and offer better guidance on how to investigate.
Thanks for the report!

Comment 3

[Chris Peterson [:cpeterson]]

Parent process controlled document navigation bug 1647550 will improve error handling of misbehaving content processes. We should add tests for these error handling cases.

P3