1490880 - Browser Console locks up the browser under heavy load

Status: NEW

(DevTools :: Console, defect, P2)

Description

[Stephan Sokolow]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:63.0) Gecko/20100101 Firefox/63.0
Build ID: 20180906162647

Steps to reproduce:

1. Install an extension that results in a flood of error messages to the browser console and heavy CPU load (though not sufficient to render the browser unusable)
2. Open the Browser Console
3. Select a bunch of the error messages to copy to the clipboard
4. Notice that the browser is becoming very slow to respond and Firefox's chrome process is monopolizing a CPU core (conky displays it at 52% CPU utilization on my dual-core system.)
5. Click the trashcan icon on the browser console
6. Notice no response
7. Click the close button on the browser console


Actual results:

One of the times, after the browser console became non-responsive, I tried deselecting the entries before clicking delete or closing the browser console. 

It took several non-responsive minutes of 100% CPU on one core, but the selection would eventually be cleared... though it didn't then become any more responsive.

In the worst case, I had to wait over 20 minutes after clicking the Close button before the console went away and the browser became responsive again and I could complete and post the bug report I'd been working on.

(The cruelest irony is that I was able to identify the extension causing the flood of errors as being the extension intended to protect against losing what's been typed into a form (Form History Control), since no other extension in my profile has a "background/contextmenu.js" to emit errors.)


Expected results:

Excessive printing to the browser console should not render the rest of the browser unresponsive.

Comment 2

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

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.