Bug 64388 – COLLECT_ON_EVERY_ALLOCATION no longer works

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Filip Pizlo]

The GC allocation path breaks if COLLECT_ON_EVERY_ALLOCATION is set.  This occurs for two reasons:

1) To collect we need JSGlobalData to be initialized, but to be initialized, JSGlobalData must perform allocations.

2) Even if this is side-stepped, the Heap::allocate() handles allocation slow cases by calling itself recursively, which always results in another forced collection if COLLECT_ON_EVERY_ALLOCATION is set.  But allocating after a collection requires the slow path to be taken.  Hence, COLLECT_ON_EVERY_ALLOCATION causes every allocation to recurse ad infinitum, invoking a full heap GC every time.

[Filip Pizlo]

Created attachment 100568 [details]
the patch

[WebKit Review Bot]

Attachment 100568 [details] did not pass style-queue:

Failed to run "['Tools/Scripts/check-webkit-style', '--diff-files', u'Source/JavaScriptCore/ChangeLog', u'Source..." exit_code: 1

Source/JavaScriptCore/heap/Heap.h:139:  The parameter name "sizeClass" adds no information, so it should be removed.  [readability/parameter_name] [5]
Total errors found: 1 in 4 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Filip Pizlo]

Created attachment 100571 [details]
the patch (fix style)

[WebKit Review Bot]

Comment on attachment 100571 [details]
the patch (fix style)

Clearing flags on attachment: 100571

Committed r90865: <http://trac.webkit.org/changeset/90865>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.