Bug 130177 - [EFL] Enable Parallel GC
Summary: [EFL] Enable Parallel GC
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: WebKit EFL (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Ryuan Choi
URL:
Keywords:
Depends on: 141290
Blocks:
  Show dependency tree / graph
 
Reported: 2014-03-12 21:41 PDT by Ryuan Choi
Modified: 2016-02-02 21:47 PST (History)
2 users (show)

See Also:

Attachments
Patch (1.19 KB, patch)
2014-03-12 21:43 PDT, Ryuan Choi 		no flags Details | Formatted Diff | Diff
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Ryuan Choi 2014-03-12 21:41:41 PDT 
Turn on Parallel GC for the EFL port
Comment 1 Ryuan Choi 2014-03-12 21:43:06 PDT 
Created attachment 226573 [details]
Patch
Comment 2 Geoffrey Garen 2014-03-12 22:21:52 PDT 
Comment on attachment 226573 [details]
Patch

r=me
Comment 3 Ryuan Choi 2014-03-12 23:00:03 PDT 
Comment on attachment 226573 [details]
Patch

Clearing flags on attachment: 226573

Committed r165527: <http://trac.webkit.org/changeset/165527>
Comment 4 Ryuan Choi 2014-03-12 23:00:11 PDT 
All reviewed patches have been landed.  Closing bug.
Comment 5 Peng Xinchao 2016-02-02 21:16:00 PST 
Hello, GC experts.

Recently I met a GC crash when PARRALLEL GC is enabled. Crash is like:

#0  0x00007ffff72a1671 in isJSString (this=0x7fffeaec0cd8) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSString.h:501
#1  visitChildren (this=0x7fffeaec0cd8) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkStack.cpp:351
#2  JSC::SlotVisitor::drain (this=0x7fffeaec0cd8) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkStack.cpp:405
#3  0x00007ffff72a19e4 in JSC::SlotVisitor::drainFromShared (this=0x7fffeaec0cd8, sharedDrainMode=JSC::SlotVisitor::MasterDrain) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkStack.cpp:498
#4  0x00007ffff729dd38 in JSC::Heap::markRoots (this=0x7fffeaec0050, fullGC=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/heap/Heap.cpp:555
#5  0x00007ffff729df8b in JSC::Heap::collect (this=0x7fffeaec0050, sweepToggle=JSC::Heap::DoNotSweep) at /home/oszi/WebKit/Source/JavaScriptCore/heap/Heap.cpp:717
#6  0x00007ffff72a410c in JSC::MarkedAllocator::allocateSlowCase (this=0x7fffeaec0158) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkedAllocator.cpp:75
#7  0x00007ffff72e84ba in JSC::MarkedAllocator::allocate (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkedAllocator.h:77
#8  JSC::MarkedSpace::allocateWithDestructor (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/heap/MarkedSpace.h:191
#9  JSC::Heap::allocateWithDestructor (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/heap/Heap.h:362
#10 allocateCell<JSC::JSFinalObject> (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSCell.h:340
#11 JSC::JSFinalObject::create (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSObject.h:439
#12 constructEmptyObject (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSObject.h:515
#13 constructEmptyObject (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSGlobalObject.h:431
#14 constructEmptyObject (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/runtime/JSGlobalObject.h:436
#15 operationNewObject (exec=<value optimized out>) at /home/oszi/WebKit/Source/JavaScriptCore/dfg/DFGOperations.cpp:305
#16 0x00007fffaaf8880d in ?? ()
#17 0x0000000000000000 in ?? ()


I checked the code of JSCore GC.

void SlotVisitor::drain()
{
    StackStats::probe();
    ASSERT(m_isInParallelMode);

#if ENABLE(PARALLEL_GC)
    if (Options::numberOfGCMarkers() > 1) {
        while (!m_stack.isEmpty()) {
            m_stack.refill();
            for (unsigned countdown = Options::minimumNumberOfScansBetweenRebalance(); m_stack.canRemoveLast() && countdown--;)
                visitChildren(*this, m_stack.removeLast());
            donateKnownParallel();
        }

        mergeOpaqueRootsIfNecessary();
        return;
    }
#endif

    while (!m_stack.isEmpty()) {
        m_stack.refill();
        while (m_stack.canRemoveLast())
            visitChildren(*this, m_stack.removeLast());
    }
}

Why is m_shared.m_markingLock not added before m_stack.refill() and m_stack.removeLast(), just like inside the function void SlotVisitor::donateKnownParallel() ?

It seems that m_stack is operated unsafely when PARRELLEL GC is enabled.

What do you think?
Comment 6 Peng Xinchao 2016-02-02 21:47:18 PST 
1