[Webkit-unassigned] [Bug 26839] Reference counting in JSC::UString is not thread safe

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=26839


jaroslav.franek at acision.com changed:

           What    |Removed                     |Added
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                 CC|                            |jaroslav.franek at acision.com




------- Comment #5 from jaroslav.franek at acision.com  2009-07-01 02:42 PDT -------
Hi gents,

We probably have a misunderstanding here. The purpose of this patch is not to
make UString thread-safe. The sole purpose is to make the increment & decrement
of the reference counter thread-safe in MT environment.

Clearly the atomic operations used in the patch would not provide thread safety
for the Ustring instance. Rather they are protecting only the 'rc' member.

This fix eliminates millions of valgrind reports that otherwise overwhelm the
valgrind output log. Please see the following summary got on the same test
case:

original code:
==9392== ERROR SUMMARY: 3511545 errors from 365 contexts (suppressed: 3670978
from 6)

patched code:
==7902== ERROR SUMMARY: 2470023 errors from 91 contexts (suppressed: 3689267
from 6)

gain: 1041522 less errors (30%)

Our main goal is to use the WebKit on Linux x86_64 platform in multi-thread
environment. The patch is important for us. Please reconsider your decision.
Thank you.


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