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Avoid deadlock caused by Cocoa code taking the ROOT lock
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In the example below, thread #11 is waiting on the ‘AppKit lock’ while thread #1 is waiting on the ROOT read lock and thread #12 is waiting on the ROOT write lock.

In thread #11, the ROOT write lock is taken/held by frame #9, TCanvas::Update, to ‘serialize’ the update to the windowing system.

In thread #1, the ‘AppKit lock’ is likely taken/held by a frame in the #16 to #40 range.

This commit remove the dead lock by removing the unnecessary use of code needing the ROOT lock within code run under the AppKit lock so that in they case thread #1 no longer need to wait for the ROOT (read) lock.

In addition it should be investigated whether the ROOT (write) lock should be taken in thread #1, frame 1 (TMacOSXSystem::ProcessPendingEvents) for the same reason it is taken in TCanvas::Update.

  thread #11
    frame #0: 0x00007fffab109bf2 libsystem_kernel.dylib`__psynch_cvwait + 10
    frame #1: 0x00007fffab1f57fa libsystem_pthread.dylib`_pthread_cond_wait + 712
    frame #2: 0x00007fff93394e34 AppKit`-[NSViewHierarchyLock lockForReadingWithExceptionHandler:] + 287
    frame #3: 0x00007fff934948ae AppKit`-[NSWindow _copyAcquiredViewHierarchyLock] + 126
    frame #4: 0x00007fff9349442c AppKit`-[NSView lockFocusIfCanDraw] + 159
    frame #5: 0x000000011c09063d libGCocoa.so`ROOT::MacOSX::X11::CommandBuffer::Flush(this=0x0000000100dbb080, impl=0x0000000100dbb000) at X11Buffer.mm:550
    frame #6: 0x000000011c04e9c4 libGCocoa.so`TGCocoa::Update(this=0x0000000100ad1bc0, mode=1) at TGCocoa.mm:536
    frame #7: 0x000000011c04ff3e libGCocoa.so`TGCocoa::UpdateWindow(this=0x0000000100ad1bc0, (null)=1) at TGCocoa.mm:776
    frame #8: 0x000000011ad70827 libGpad.so`TCanvas::Flush(this=0x000000012274e740) at TCanvas.cxx:1096
    frame #9: 0x000000011ad7830f libGpad.so`TCanvas::Update(this=0x000000012274e740) at TCanvas.cxx:2287
    frame #10: 0x0000000100fe4e86 threadsh2_C.so`handle2((null)=0x0000000000000001) at threadsh2.C:105
    frame #11: 0x0000000100f55680 libThread.so`TThread::Function(ptr=0x0000000122753b00) at TThread.cxx:821
    frame #12: 0x00007fffab1f493b libsystem_pthread.dylib`_pthread_body + 180
    frame #13: 0x00007fffab1f4887 libsystem_pthread.dylib`_pthread_start + 286
    frame #14: 0x00007fffab1f408d libsystem_pthread.dylib`thread_start + 13

  thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    frame #0: 0x00007fffab109bf2 libsystem_kernel.dylib`__psynch_cvwait + 10
    frame #1: 0x00007fffab1f57fa libsystem_pthread.dylib`_pthread_cond_wait + 712
    frame #2: 0x00007fffa9b734cd libc++.1.dylib`std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47
    frame #3: 0x0000000100f76b6f libThread.so`void std::__1::condition_variable_any::wait<std::__1::unique_lock<std::__1::mutex> >(this=0x0000000122753a28, __lock=0x00007fff5fbf5cf8) at condition_variable:202
    frame #4: 0x0000000100f6887e libThread.so`ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::ReadLock() [inlined] void std::__1::condition_variable_any::wait<std::__1::unique_lock<std::__1::mutex>, ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::ReadLock()::'lambda'()>(this=0x0000000122753a28, __lock=0x00007fff5fbf5cf8, __pred=(anonymous class) @ 0x00007fff5fbf5e08)::'lambda'()) at condition_variable:211
    frame #5: 0x0000000100f68857 libThread.so`ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::ReadLock(this=0x00000001227539d8) at TReentrantRWLock.cxx:95
    frame #6: 0x0000000100f5c719 libThread.so`ROOT::TRWMutexImp<std::__1::mutex, ROOT::Internal::RecurseCounts>::ReadLock(this=0x00000001227539d0) at TRWMutexImp.cxx:33
    frame #7: 0x00000001000f52d1 libCore.so`ROOT::TReadLockGuard::TReadLockGuard(this=0x00007fff5fbf5f48, mutex=0x00000001227539d0) at TVirtualRWMutex.h:89
    frame #8: 0x00000001000f275d libCore.so`ROOT::TReadLockGuard::TReadLockGuard(this=0x00007fff5fbf5f48, mutex=0x00000001227539d0) at TVirtualRWMutex.h:88
    frame #9: 0x00000001002fcebf libCore.so`THashTable::FindObject(this=0x0000000100b0e120, name="TGTextView") const at THashTable.cxx:242
    frame #10: 0x00000001003a67fd libCore.so`TClass::GetClass(name="TGTextView", load=true, silent=true) at TClass.cxx:2900
    frame #11: 0x00000001003c9e16 libCore.so`TClass::InheritsFrom(this=0x0000000118fe1250, classname="TGTextView") const at TClass.cxx:4683
    frame #12: 0x000000010024cb6e libCore.so`TObject::InheritsFrom(this=0x0000000126908de0, classname="TGTextView") const at TObject.cxx:445
    frame #13: 0x000000011c03e47f libGCocoa.so`ROOT::MacOSX::X11::ViewIsTextView(viewID=116) at QuartzWindow.mm:899
    frame #14: 0x000000011c03e518 libGCocoa.so`ROOT::MacOSX::X11::ViewIsTextView(view=0x0000000126908ee0) at QuartzWindow.mm:907
    frame #15: 0x000000011c04706c libGCocoa.so`::-[QuartzView drawRect:](self=0x0000000126908ee0, _cmd="drawRect:", dirtyRect=(origin = (x = 0, y = 0), size = (width = 29, height = 21))) at QuartzWindow.mm:2728
    frame #16: 0x00007fff934a4f99 AppKit`-[NSView _drawRect:clip:] + 2276
    frame #17: 0x00007fff934f4f2f AppKit`-[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 1753
    frame #18: 0x00007fff934f539a AppKit`-[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2884
    frame #19: 0x00007fff934f539a AppKit`-[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2884
    frame #20: 0x00007fff934f539a AppKit`-[NSView _recursiveDisplayAllDirtyWithLockFocus:visRect:] + 2884
    frame #21: 0x00007fff934a2ad2 AppKit`-[NSView _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 837
    frame #22: 0x00007fff934a22af AppKit`-[NSThemeFrame _recursiveDisplayRectIfNeededIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:topView:] + 334
    frame #23: 0x00007fff934a06d8 AppKit`-[NSView _displayRectIgnoringOpacity:isVisibleRect:rectIsVisibleRectForView:] + 2452
    frame #24: 0x00007fff9349bfca AppKit`-[NSView displayIfNeeded] + 1748
    frame #25: 0x00007fff9349b8db AppKit`-[NSWindow displayIfNeeded] + 230
    frame #26: 0x00007fff93bfbcb4 AppKit`___NSWindowGetDisplayCycleObserver_block_invoke.6228 + 277
    frame #27: 0x00007fff9349b3b9 AppKit`__37+[NSDisplayCycle currentDisplayCycle]_block_invoke + 454
    frame #28: 0x00007fff9b384cc6 QuartzCore`CA::Transaction::run_commit_handlers(CATransactionPhase) + 46
    frame #29: 0x00007fff9b48e8ac QuartzCore`CA::Context::commit_transaction(CA::Transaction*) + 160
    frame #30: 0x00007fff9b3837a1 QuartzCore`CA::Transaction::commit() + 475
    frame #31: 0x00007fff9377e8b1 AppKit`__37+[NSDisplayCycle currentDisplayCycle]_block_invoke.31 + 323
    frame #32: 0x00007fff95874d37 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
    frame #33: 0x00007fff95874ca7 CoreFoundation`__CFRunLoopDoObservers + 391
    frame #34: 0x00007fff958556d9 CoreFoundation`__CFRunLoopRun + 873
    frame #35: 0x00007fff95855114 CoreFoundation`CFRunLoopRunSpecific + 420
    frame #36: 0x00007fff94db5ebc HIToolbox`RunCurrentEventLoopInMode + 240
    frame #37: 0x00007fff94db5bf9 HIToolbox`ReceiveNextEventCommon + 184
    frame #38: 0x00007fff94db5b26 HIToolbox`_BlockUntilNextEventMatchingListInModeWithFilter + 71
    frame #39: 0x00007fff9334ca54 AppKit`_DPSNextEvent + 1120
    frame #40: 0x00007fff93ac87ee AppKit`-[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 2796
    frame #41: 0x0000000100491031 libCore.so`TMacOSXSystem::ProcessPendingEvents(this=0x0000000100c06d60) at TMacOSXSystem.mm:473
    frame #42: 0x000000010049097d libCore.so`TMacOSXSystem::DispatchOneEvent(this=0x0000000100c06d60, pendingOnly=true) at TMacOSXSystem.mm:365
    frame #43: 0x0000000100294f4b libCore.so`TSystem::ProcessEvents(this=0x0000000100c06d60) at TSystem.cxx:429
    frame #44: 0x0000000100fe5844 threadsh2_C.so`threadsh2() at threadsh2.C:196
    frame #45: 0x0000000100fec06a
    frame #46: 0x0000000103d7dc2f libCling.so`cling::IncrementalExecutor::executeWrapper(this=0x0000000100a1d410, function=(Data = "_Z15__cling_Un1Qu30Pv", Length = 21), returnValue=0x00007fff5fbfbde0) at IncrementalExecutor.h:196
    frame #47: 0x0000000103d7db1f libCling.so`cling::Interpreter::RunFunction(this=0x0000000100a0e3b0, FD=0x000000011780f6b0, res=0x00007fff5fbfbde0) at Interpreter.cpp:980
    frame #48: 0x0000000103d7a92a libCling.so`cling::Interpreter::EvaluateInternal(this=0x0000000100a0e3b0, input="threadsh2()", CO=CompilationOptions @ 0x00007fff5fbfaae8, V=0x00007fff5fbfbde0, T=0x0000000000000000, wrapPoint=44) at Interpreter.cpp:1232
    frame #49: 0x0000000103d79e27 libCling.so`cling::Interpreter::process(this=0x0000000100a0e3b0, input="threadsh2()", V=0x00007fff5fbfbde0, T=0x0000000000000000, disableValuePrinting=false) at Interpreter.cpp:684
    frame #50: 0x0000000103e552a5 libCling.so`cling::MetaProcessor::process(this=0x0000000100b65aa0, input_line=(Data = "threadsh2()", Length = 11), compRes=0x00007fff5fbfb540, result=0x00007fff5fbfbde0, disableValuePrinting=false) at MetaProcessor.cpp:341
    frame #51: 0x000000010397bd63 libCling.so`HandleInterpreterException(metaProcessor=0x0000000100b65aa0, input_line="threadsh2()", compRes=0x00007fff5fbfb540, result=0x00007fff5fbfbde0) at TCling.cxx:2053
    frame #52: 0x000000010397a16e libCling.so`TCling::ProcessLine(this=0x0000000100a0de40, line=".X  /opt/build/root_builds/master.debug/tutorials/thread/./threadsh2.C+", error=0x00007fff5fbfd694) at TCling.cxx:2170
    frame #53: 0x0000000103984436 libCling.so`TCling::ProcessLineSynch(this=0x0000000100a0de40, line=".X  /opt/build/root_builds/master.debug/tutorials/thread/./threadsh2.C+", error=0x00007fff5fbfd694) at TCling.cxx:3044
    frame #54: 0x00000001001f3133 libCore.so`TApplication::ExecuteFile(file="threadsh2.C+", error=0x00007fff5fbfd694, keep=false) at TApplication.cxx:1143
    frame #55: 0x00000001001f19e0 libCore.so`TApplication::ProcessFile(this=0x0000000100b113e0, file="threadsh2.C+", error=0x00007fff5fbfd694, keep=false) at TApplication.cxx:1015
    frame #56: 0x00000001001f138f libCore.so`TApplication::ProcessLine(this=0x0000000100b113e0, line=".x threadsh2.C+", sync=false, err=0x00007fff5fbfd694) at TApplication.cxx:988
    frame #57: 0x000000010009878d libRint.so`TRint::ProcessLineNr(this=0x0000000100b113e0, filestem="ROOT_cli_", line=".x threadsh2.C+", error=0x00007fff5fbfd694) at TRint.cxx:756
    frame #58: 0x0000000100097daf libRint.so`TRint::Run(this=0x0000000100b113e0, retrn=false) at TRint.cxx:416
    frame #59: 0x00000001000027a4 root.exe`main(argc=1, argv=0x00007fff5fbff780) at rmain.cxx:30
    frame #60: 0x00007fffaafdb235 libdyld.dylib`start + 1

  thread #12
    frame #0: 0x00007fffab109bf2 libsystem_kernel.dylib`__psynch_cvwait + 10
    frame #1: 0x00007fffab1f57fa libsystem_pthread.dylib`_pthread_cond_wait + 712
    frame #2: 0x00007fffa9b734cd libc++.1.dylib`std::__1::condition_variable::wait(std::__1::unique_lock<std::__1::mutex>&) + 47
    frame #3: 0x0000000100f76b6f libThread.so`void std::__1::condition_variable_any::wait<std::__1::unique_lock<std::__1::mutex> >(this=0x0000000122753a28, __lock=0x0000700009f18898) at condition_variable:202
    frame #4: 0x0000000100f697b4 libThread.so`ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::WriteLock() [inlined] void std::__1::condition_variable_any::wait<std::__1::unique_lock<std::__1::mutex>, ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::WriteLock()::'lambda'()>(this=0x0000000122753a28, __lock=0x0000700009f18898, __pred=(anonymous class) @ 0x0000700009f18a28)::'lambda'()) at condition_variable:211
    frame #5: 0x0000000100f69790 libThread.so`ROOT::TReentrantRWLock<std::__1::mutex, ROOT::Internal::RecurseCounts>::WriteLock(this=0x00000001227539d8) at TReentrantRWLock.cxx:175
    frame #6: 0x0000000100f5c779 libThread.so`ROOT::TRWMutexImp<std::__1::mutex, ROOT::Internal::RecurseCounts>::WriteLock(this=0x00000001227539d0) at TRWMutexImp.cxx:42
    frame #7: 0x0000000100f57df6 libThread.so`ROOT::TVirtualRWMutex::Lock(this=0x00000001227539d0) at TVirtualRWMutex.h:52
    frame #8: 0x00000001039b2dd9 libCling.so`TLockGuard::TLockGuard(this=0x0000700009f18b48, mutex=0x00000001227539d0) at TVirtualMutex.h:85
    frame #9: 0x000000010397ba8d libCling.so`TLockGuard::TLockGuard(this=0x0000700009f18b48, mutex=0x00000001227539d0) at TVirtualMutex.h:85
    frame #10: 0x00000001039aa152 libCling.so`TCling::ClassInfo_Factory(this=0x0000000100a0de40, all=true) const at TCling.cxx:7216
    frame #11: 0x00000001004150ba libCore.so`TMethodCall::Init(this=0x0000700009f18d80, cl=0x0000000100af0470, method="Print", params="", objectIsConst=false) at TMethodCall.cxx:259
    frame #12: 0x0000000100414ff3 libCore.so`TMethodCall::TMethodCall(this=0x0000700009f18d80, cl=0x0000000100af0470, method="Print", params="") at TMethodCall.cxx:62
    frame #13: 0x000000010041519d libCore.so`TMethodCall::TMethodCall(this=0x0000700009f18d80, cl=0x0000000100af0470, method="Print", params="") at TMethodCall.cxx:61
    frame #14: 0x0000000100fe471a threadsh2_C.so`handle1((null)=0x0000000000000000) at threadsh2.C:48
    frame #15: 0x0000000100f55680 libThread.so`TThread::Function(ptr=0x0000000122754790) at TThread.cxx:821
    frame #16: 0x00007fffab1f493b libsystem_pthread.dylib`_pthread_body + 180
    frame #17: 0x00007fffab1f4887 libsystem_pthread.dylib`_pthread_start + 286
    frame #18: 0x00007fffab1f408d libsystem_pthread.dylib`thread_start + 13
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@pcanal
pcanal committed Feb 5, 2018
1 parent 8ac53b7 commit c2e3a62
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Showing 3 changed files with 29 additions and 5 deletions.
28 changes: 23 additions & 5 deletions graf2d/cocoa/src/QuartzWindow.mm
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,9 @@
#include "TSystem.h"
#include "TGCocoa.h"
#include "TROOT.h"
#include "TGTextView.h"
#include "TGView.h"
#include "TGCanvas.h"


namespace ROOT {
Expand Down Expand Up @@ -896,7 +899,10 @@ bool ViewIsTextView(unsigned viewID)
const TGWindow * const window = gClient->GetWindowById(viewID);
if (!window)
return false;
return window->InheritsFrom("TGTextView");
// This code used to use TObject::InheritsFrom, however since this is
// run under the AppKit, we can not call core/meta functions, otherwise
// we will run into deadlocks.
return dynamic_cast<const TGTextView*>(window);
}

//______________________________________________________________________________
Expand All @@ -916,7 +922,10 @@ bool ViewIsTextViewFrame(NSView<X11Window> *view, bool checkParent)
if (!window)
return false;

if (!window->InheritsFrom("TGViewFrame"))
// This code used to use TObject::InheritsFrom, however since this is
// run under the AppKit, we can not call core/meta functions, otherwise
// we will run into deadlocks.
if (!dynamic_cast<const TGViewFrame*>(window))
return false;

if (!checkParent)
Expand All @@ -934,7 +943,10 @@ bool ViewIsHtmlView(unsigned viewID)
const TGWindow * const window = gClient->GetWindowById(viewID);
if (!window)
return false;
return window->InheritsFrom("TGHtml");
// This code used to use TObject::InheritsFrom, however since this is
// run under the AppKit, we can not call core/meta functions, otherwise
// we will run into deadlocks.
return window->TestBit(TGWindow::kIsHtmlView);
}

//______________________________________________________________________________
Expand All @@ -955,7 +967,10 @@ bool ViewIsHtmlViewFrame(NSView<X11Window> *view, bool checkParent)
if (!window)
return false;

if (!window->InheritsFrom("TGViewFrame"))
// This code used to use TObject::InheritsFrom, however since this is
// run under the AppKit, we can not call core/meta functions, otherwise
// we will run into deadlocks.
if (!dynamic_cast<const TGViewFrame*>(window))
return false;

if (!checkParent)
Expand Down Expand Up @@ -2705,7 +2720,10 @@ - (void) drawRect : (NSRect) dirtyRect
if (self.fQuartzWindow.fShapeCombineMask)
X11::ClipToShapeMask(self, fContext);

if (window->InheritsFrom("TGContainer"))//It always has an ExposureMask.
// This code used to use TObject::InheritsFrom, however since this is
// run under the AppKit, we can not call core/meta functions, otherwise
// we will run into deadlocks.
if (dynamic_cast<const TGContainer*>(window))//It always has an ExposureMask.
vx->GetEventTranslator()->GenerateExposeEvent(self, [self visibleRect]);

if (fEventMask & kExposureMask) {
Expand Down
4 changes: 4 additions & 0 deletions gui/gui/inc/TGWindow.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,10 @@ friend class TGClient;
kEditDisableKeyEnable = BIT(8) // window can handle keyboard events
};

enum EStatusBits {
kIsHtmlView = BIT(14)
};

TGWindow(const TGWindow *p = 0, Int_t x = 0, Int_t y = 0,
UInt_t w = 0, UInt_t h = 0, UInt_t border = 0,
Int_t depth = 0,
Expand Down
2 changes: 2 additions & 0 deletions gui/guihtml/src/TGHtml.cxx
View file
Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,8 @@ int HtmlDepth = 0;

TGHtml::TGHtml(const TGWindow *p, int w, int h, int id) : TGView(p, w, h, id)
{
SetBit(kIsHtmlView);

int i;

fExiting = 0;
Expand Down

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