Comment 7 for bug 120991

I'm able to reproduce one instance of firefox hanging without any extension.

Note however that this particular hang is different than the above.
Hopefully, it will give developers an easy way to reproduce one hang condition.

Steps to reproduce:
--------------------------
To ensure no extensions are used I start firefox in safe mode from a shell:

    $ firefox -safe-mode

Now go to youtube.com
- Start clicking on videos at random, it doesn't matter which.
- Alternate between clicking on new videos and clicking the back button to go to previous videos.
- Click regardless of the state of the video playback. interrupting playing videos in the middle

After less than one minute (about 10-30 clicks on average) of going through this exercise
I'm able to get to a state where firefox is hung and stops responding to user input.

strace on the most recent firefox-bin process shows this:

    $ strace -p 1920
    Process 1920 attached - interrupt to quit
    futex(0xae575bd8, FUTEX_WAIT, 3076, NULL

This is 100% reproducible in my env, and it is without any extensions I can see.
Unless you count the youtube flash-video plugin as an extension.

Does this help?