Hmm, this issue has been reported before, but I could never find why it happens, as it seems so difficult to reproduce. Is there a way how you can (reliably) reproduce this? Do you know with which request/code path this happens? Is it in a single or multi-threaded environment?

Hi Derick,

I can guarantee that it'll happen some time in the next month but I cannot easily reproduce on a whim.

It's a single threaded php-fpm implementation.

I'll be at phpwarks tonight if you want to discuss or poke around the affected server.

I can see that it's stuck here:
void xdebug_llist_empty(xdebug_llist l, void user)
{
while (xdebug_llist_count(l) > 0) {
xdebug_llist_remove(l, XDEBUG_LLIST_TAIL(l), user);
}
}

with tail == NULL llist_remove() immediately returns, but the l->size is still 1 (in my case), so this loop has no end.
I'll try to reproduce it, too, but no guarantees, sorry..

Good luck Antony! I never managed :-/

Changing this to "acknowledged", but I won't work on this unless somebody shows me a reproducible case.

Is this something either of you have been able to conclusively reproduce yet? If not, I think I will close this issue.

I have added the defensive check for 2.5.0RC2.