tree 3ef897b61ebc670eecf8765ba9d6e920306ae7dd
parent 6f08ee572585d855ec40187b11b9c78e1962939f
author tzagallo@apple.com <tzagallo@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1563180442 +0000
committer tzagallo@apple.com <tzagallo@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1563180442 +0000

Concurrent GC should not rely on current phase to determine if it's safe to steal conn
https://bugs.webkit.org/show_bug.cgi?id=199786
<rdar://problem/52505197>

Reviewed by Saam Barati.

In r246507, we fixed a race condition in the concurrent GC where the mutator might steal
the conn from the collector thread while it transitions from the End phase to NotRunning.
However, that fix was not sufficient. In the case that the mutator steals the conn, and the
execution interleaves long enough for the mutator to progress to a different collection phase,
the collector will resume in a phase other than NotRunning, and hence the check added to
NotRunning will not suffice. To fix that, we add a new variable to track whether the collector
thread is running (m_collectorThreadIsRunning) and use it to determine whether it's safe to
steal the conn, rather than relying on m_currentPhase.

* heap/Heap.cpp:
(JSC::Heap::runNotRunningPhase):
(JSC::Heap::requestCollection):
* heap/Heap.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@247426 268f45cc-cd09-0410-ab3c-d52691b4dbfc