[Webkit-unassigned] [Bug 31693] New: isMainThread() on Chromium (Mac and Linux) is so slow it timeouts LayoutTests..

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=31693

           Summary: isMainThread() on Chromium (Mac and Linux) is so slow
                    it timeouts LayoutTests..
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: PC
        OS/Version: Mac OS X 10.5
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Web Template Framework
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: dimich at chromium.org
                CC: ap at webkit.org, dglazkov at chromium.org,
                    levin at chromium.org


http://trac.webkit.org/changeset/51158 added ASSERT(isMainThread()) to
TreeShared methods. This practically didn't slow down debug build on Mac and
Windows, but on Chromium some layout tests started to timeout. For example,
editing/selection/extend-selection.html execution time grew 15 times (!). This
test operates with selection and it does a lot of operations like
Position::previous() that churns refcout on Nodes.

Turned out the isMainThread() on pthread-based Chromium (Mac and Linux)
involves mapping through threadMap, which in turn takes 2 Mutexes to lock - in
identifierByPthreadHandle() and in iterator code.
By comparing handle itself rather then mapped Id the time required by
isMainThread() goes back to reasonable.

Patch is coming.

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.