Re: [PATCH] Deadlock in CGLGraphicsConfig.getCGLConfigInfo

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Re: [PATCH] Deadlock in CGLGraphicsConfig.getCGLConfigInfo

Sergey Bylokhov
Hi, Karl.

The correct alias to discuss this issue is 2d-dev.

Looks like this bug was reported before.

Your evaluation and the fix seems reasonable.
If you already signed the OCA[1] then you can send an official review request to 2d-dev. An example:  




I have encountered a deadlock in Java 1.8.0_112 when changing between discrete and integrated GPU on a retina MacBook Pro. The deadlock is between:

CGLGraphicsConfig.getCGLConfigInfo, running on AWT.EventQueue, trying to call [GraphicsConfigUtil _getCGLConfigInfo:] on
the main thread (AppKit thread) while it holds the AWT lock and is synchronized on CGraphicsEnvironment.

and

A) the AppKit main thread trying to call CGraphicsEnvironment._displayReconfiguration (via displaycb_handle in CGraphicsEnv.m)
and synchronizing on CGraphicsEnvironment—deadlock.

or

B) the AppKit main thread trying to render, and trying to acquire the OGLRenderQueue lock (which is the the AWT lock)


SUPPORTING STACK DUMPS

- SCENARIO A

CGraphicsEnvironment._displayReconfiguration is called on the main thread since
8041900: [macosx] Java forces the use of discrete GPU (https://bugs.openjdk.java.net/browse/JDK-8041900 <https://bugs.openjdk.java.net/browse/JDK-8041900>) which appears as changeset 11227.
In the native thread dump below you can see the frame for displaycb_handle which is the block dispatched to the main thread to call
CGraphicsEnvironment._displayReconfiguration.

Java stacks

"AWT-EventQueue-0" #16 prio=6 os_prio=31 tid=0x00007fbc72a0a800 nid=0x1251f runnable [0x000070000e443000]
  java.lang.Thread.State: RUNNABLE
at sun.java2d.opengl.CGLGraphicsConfig.getCGLConfigInfo(Native Method)
at sun.java2d.opengl.CGLGraphicsConfig.getConfig(CGLGraphicsConfig.java:147)
at sun.awt.CGraphicsDevice.<init>(CGraphicsDevice.java:64)
at sun.awt.CGraphicsEnvironment.initDevices(CGraphicsEnvironment.java:163)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)
[SNIP]
at java.awt.Container.layout(Container.java:1510)
at java.awt.Container.doLayout(Container.java:1499)
at java.awt.Container.validateTree(Container.java:1695)
[SNIP]
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1750)
[SNIP]
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

"AppKit Thread" #11 daemon prio=5 os_prio=31 tid=0x00007fbc75046800 nid=0x307 waiting for monitor entry [0x00007fff5b579000]
  java.lang.Thread.State: BLOCKED (on object monitor)
at sun.awt.CGraphicsEnvironment._displayReconfiguration(CGraphicsEnvironment.java:129)
- waiting to lock <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)

Native stacks

 Thread 0x6828c3           DispatchQueue 1           Thread name "AppKit Thread"                         1000 samples (1-1000)     priority 46 (base 46)     cpu time <0.001
 1000  start + 52 (Charles + 5156) [0x104682424]
   1000  main + 153 (Charles + 5321) [0x1046824c9]
     1000  launch + 10872 (Charles + 16520) [0x104685088]
       1000  JLI_Launch + 1952 (libjli.dylib + 5668) [0x104702624]
         1000  CreateExecutionEnvironment + 871 (libjli.dylib + 22781) [0x1047068fd]
           1000  CFRunLoopRunSpecific + 420 (CoreFoundation + 555380) [0x7fff97665974]
             1000  __CFRunLoopRun + 934 (CoreFoundation + 556918) [0x7fff97665f76]
               1000  __CFRunLoopDoSources0 + 557 (CoreFoundation + 559741) [0x7fff97666a7d]
                 1000  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 686465) [0x7fff97685981]
                   1000  __NSThreadPerformPerform + 326 (Foundation + 465034) [0x7fff990c988a]
                     1000  -[AWTStarter starter:] + 905 (libawt_lwawt.dylib + 286207) [0x113081dff]
                       1000  +[NSApplicationAWT runAWTLoopWithApp:] + 156 (libosxapp.dylib + 8525) [0x1130fa14d]
[SNIP]
                                                 1000  +[JNFRunLoop _performCopiedBlock:] + 17 (JavaNativeFoundation + 28474) [0x112d0df3a]
                                                   1000  __displaycb_handle_block_invoke_1 + 172 (libawt_lwawt.dylib + 119659) [0x11305936b]
                                                     1000  JNFPerformEnvBlock + 87 (JavaNativeFoundation + 27229) [0x112d0da5d]
                                                       1000  __displaycb_handle_block_invoke_2 + 80 (libawt_lwawt.dylib + 119988) [0x1130594b4]
                                                         1000  JNFCallVoidMethod + 187 (JavaNativeFoundation + 13743) [0x112d0a5af]
                                                           1000  jni_CallVoidMethodV + 248 (libjvm.dylib + 3069241) [0x106301539]
                                                             1000  jni_invoke_nonstatic(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) + 748 (libjvm.dylib + 3124227) [0x10630ec03]
                                                               1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x1062f4396]
                                                                 1000  ??? [0x113db94e7]
                                                                   1000  ??? [0x113dde021]
                                                                     1000  InterpreterRuntime::monitorenter(JavaThread*, BasicObjectLock*) + 165 (libjvm.dylib + 2995347) [0x1062ef493]
                                                                       1000  ObjectMonitor::enter(Thread*) + 472 (libjvm.dylib + 4524724) [0x106464ab4]
                                                                         1000  ObjectMonitor::EnterI(Thread*) + 532 (libjvm.dylib + 4521584) [0x106463e70]
                                                                           1000  os::PlatformEvent::park(long) + 404 (libjvm.dylib + 4561328) [0x10646d9b0]
                                                                             1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                              *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]

 Thread 0x68292c           Thread name "Java: AWT-EventQueue-0"                1000 samples (1-1000)     priority 31 (base 31)
 1000  thread_start + 13 (libsystem_pthread.dylib + 12797) [0x7fffacdd51fd]
   1000  _pthread_start + 286 (libsystem_pthread.dylib + 14839) [0x7fffacdd59f7]
     1000  _pthread_body + 180 (libsystem_pthread.dylib + 15019) [0x7fffacdd5aab]
       1000  java_start(Thread*) + 246 (libjvm.dylib + 4574506) [0x106470d2a]
         1000  JavaThread::run() + 448 (libjvm.dylib + 5486408) [0x10654f748]
           1000  JavaThread::thread_main_inner() + 155 (libjvm.dylib + 5480593) [0x10654e091]
             1000  thread_entry(JavaThread*, Thread*) + 124 (libjvm.dylib + 3270354) [0x1063326d2]
               1000  JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*) + 74 (libjvm.dylib + 3017936) [0x1062f4cd0]
                 1000  JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*) + 356 (libjvm.dylib + 3017508) [0x1062f4b24]
                   1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x1062f4396]
[SNIP]
                                                                                           1000  Java_sun_java2d_opengl_CGLGraphicsConfig_getCGLConfigInfo + 279 (libawt_lwawt.dylib + 107562) [0x11305642a]
                                                                                             1000  -[NSObject(NSThreadPerformAdditions) performSelectorOnMainThread:withObject:waitUntilDone:] + 131 (Foundation + 203394) [0x7fff99089a82]
                                                                                               1000  -[NSObject(NSThreadPerformAdditions) performSelector:onThread:withObject:waitUntilDone:modes:] + 904 (Foundation + 204424) [0x7fff99089e88]
                                                                                                 1000  -[NSCondition wait] + 240 (Foundation + 208331) [0x7fff9908adcb]
                                                                                                   1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                                                    *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]






- Scenario B

Java stacks

"AWT-EventQueue-0" #15 prio=6 os_prio=31 tid=0x00007fba611d2000 nid=0x1260f runnable [0x0000700005365000]
  java.lang.Thread.State: RUNNABLE
at sun.java2d.opengl.CGLGraphicsConfig.getCGLConfigInfo(Native Method)
at sun.java2d.opengl.CGLGraphicsConfig.getConfig(CGLGraphicsConfig.java:147)
at sun.awt.CGraphicsDevice.<init>(CGraphicsDevice.java:64)
at sun.awt.CGraphicsEnvironment.initDevices(CGraphicsEnvironment.java:163)
- locked <0x00000006c0df8c18> (a sun.awt.CGraphicsEnvironment)
at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0df8c18> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)
at net.miginfocom.layout.UnitValue.getPixelsExact(UnitValue.java:305)
at net.miginfocom.layout.UnitValue.getPixels(UnitValue.java:281)
[SNIP]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

"AppKit Thread" #11 daemon prio=5 os_prio=31 tid=0x00007fba59869800 nid=0x307 waiting on condition [0x00007fff52ac2000]
  java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <0x00000006c053b688> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
at sun.awt.SunToolkit.awtLock(SunToolkit.java:253)
at sun.java2d.pipe.RenderQueue.lock(RenderQueue.java:112)
at sun.java2d.opengl.CGLLayer.drawInCGLContext(CGLLayer.java:139)

Native stacks

 Thread 0x6764ca           DispatchQueue 1           Thread name "AppKit Thread"                         1000 samples (1-1000)     priority 46 (base 46)
 1000  start + 52 (Charles + 5156) [0x10d139424]
   1000  main + 153 (Charles + 5321) [0x10d1394c9]
     1000  launch + 10872 (Charles + 16520) [0x10d13c088]
       1000  JLI_Launch + 1952 (libjli.dylib + 5668) [0x10d1b9624]
         1000  CreateExecutionEnvironment + 871 (libjli.dylib + 22781) [0x10d1bd8fd]
           1000  CFRunLoopRunSpecific + 420 (CoreFoundation + 555380) [0x7fff97665974]
             1000  __CFRunLoopRun + 934 (CoreFoundation + 556918) [0x7fff97665f76]
               1000  __CFRunLoopDoSources0 + 557 (CoreFoundation + 559741) [0x7fff97666a7d]
                 1000  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 686465) [0x7fff97685981]
                   1000  __NSThreadPerformPerform + 326 (Foundation + 465034) [0x7fff990c988a]
                     1000  -[AWTStarter starter:] + 905 (libawt_lwawt.dylib + 286207) [0x12abc3dff]
                       1000  +[NSApplicationAWT runAWTLoopWithApp:] + 156 (libosxapp.dylib + 8525) [0x12ac3c14d]
[SNIP]
                                             1000  CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 108 (QuartzCore + 69522) [0x7fff9d393f92]
                                               1000  CA::Transaction::commit() + 475 (QuartzCore + 67121) [0x7fff9d393631]
                                                 1000  CA::Context::commit_transaction(CA::Transaction*) + 280 (QuartzCore + 1153144) [0x7fff9d49c878]
                                                   1000  CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 35 (QuartzCore + 1196185) [0x7fff9d4a7099]
                                                     1000  CA::Layer::display_if_needed(CA::Transaction*) + 572 (QuartzCore + 1195886) [0x7fff9d4a6f6e]
                                                       1000  -[CAOpenGLLayer _display] + 351 (QuartzCore + 1117583) [0x7fff9d493d8f]
                                                         1000  CAOpenGLLayerDraw(CAOpenGLLayer*, double, CVTimeStamp const*, unsigned int) + 873 (QuartzCore + 1118737) [0x7fff9d494211]
                                                           1000  -[CGLLayer drawInCGLContext:pixelFormat:forLayerTime:displayTime:] + 287 (libawt_lwawt.dylib + 109022) [0x12ab989de]
                                                             1000  JNFCallVoidMethod + 187 (JavaNativeFoundation + 13743) [0x12a84f5af]
                                                               1000  jni_CallVoidMethodV + 248 (libjvm.dylib + 3069241) [0x10edb8539]
                                                                 1000  jni_invoke_nonstatic(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) + 748 (libjvm.dylib + 3124227) [0x10edc5c03]
                                                                   1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x10edab396]
                                                                     1000  ??? [0x10ffa0854]
                                                                       1000  ??? [0x11027642a]
                                                                         1000  Unsafe_Park + 126 (libjvm.dylib + 5571927) [0x10f01b557]
                                                                           1000  Parker::park(bool, long) + 495 (libjvm.dylib + 4560765) [0x10ef2477d]
                                                                             1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                              *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]

 Thread 0x67652b           Thread name "Java: AWT-EventQueue-0"                1000 samples (1-1000)     priority 31 (base 31)
 1000  thread_start + 13 (libsystem_pthread.dylib + 12797) [0x7fffacdd51fd]
   1000  _pthread_start + 286 (libsystem_pthread.dylib + 14839) [0x7fffacdd59f7]
     1000  _pthread_body + 180 (libsystem_pthread.dylib + 15019) [0x7fffacdd5aab]
       1000  java_start(Thread*) + 246 (libjvm.dylib + 4574506) [0x10ef27d2a]
         1000  JavaThread::run() + 448 (libjvm.dylib + 5486408) [0x10f006748]
           1000  JavaThread::thread_main_inner() + 155 (libjvm.dylib + 5480593) [0x10f005091]
             1000  thread_entry(JavaThread*, Thread*) + 124 (libjvm.dylib + 3270354) [0x10ede96d2]
[SNIP]
                                                                                           1000  ??? [0x10f7a0734]
                                                                                             1000  Java_sun_java2d_opengl_CGLGraphicsConfig_getCGLConfigInfo + 279 (libawt_lwawt.dylib + 107562) [0x12ab9842a]
                                                                                               1000  -[NSObject(NSThreadPerformAdditions) performSelectorOnMainThread:withObject:waitUntilDone:] + 131 (Foundation + 203394) [0x7fff99089a82]
                                                                                                 1000  -[NSObject(NSThreadPerformAdditions) performSelector:onThread:withObject:waitUntilDone:modes:] + 904 (Foundation + 204424) [0x7fff99089e88]
                                                                                                   1000  -[NSCondition wait] + 240 (Foundation + 208331) [0x7fff9908adcb]
                                                                                                     1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                                                      *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]


INTERPRETATION

The deadlock is a race condition when macOS changes between the discrete and integrated GPU.

When the GPU changes, the result of CGraphicsEnvironment.getMainDisplayID() changes immediately (There is a comment in CGraphicsEnvironment.m
that notes that the display ID changes in this case, and I have verified this) to return the new displayID, while the devices map is only built once initDevices() is called.

CGLGraphicsConfig.getCGLConfigInfo (which is called as a consequence of initDevices, as per stack traces) calls out and waits on the AppKit main thread. I think this is
always dangerous due to the locks that the code calling it holds. I think we should avoid getCGLConfigInfo being called on anything but the AppKit main thread. I believe
this was the intention of 8041900: [macosx] Java forces the use of discrete GPU (https://bugs.openjdk.java.net/browse/JDK-8041900 <https://bugs.openjdk.java.net/browse/JDK-8041900>).

CGraphicsEnvironment.getDefaultScreenDevice() is called from AWT layout code (as per the stacks) and it calls CGraphicsEnvironment.getMainDisplayID() each time.
If CGraphicsEnvironment.getDefaultScreenDevice() is called _after_ the GPU change, but _before_ CGraphicsEnvironment._displayReconfiguration() has been called,
the CGraphicsDevice for the new display ID cannot be found in the devices Map, so initDevices() is called from CGraphicsEnvironment.getDefaultScreenDevice()
on the AWT-EventQueue thread.

There is a note in getDefaultScreenDevice() for this case:
   we do not expect that this may happen, the only response is to re-initialize the list of devices

Calling initDevices() here results in a call to CGLGraphicsConfig.getCGLConfigInfo, which then calls
[GraphicsConfigUtil _getCGLConfigInfo:] on the AppKit main thread and waits for the result.

As the current thread (AWT Event queue) is holding the AWT lock, and is synchronized on CGraphicsEnvironment, the two deadlock
conditions described above can occur.


REPRODUCABILITY

This happens quite regularly on my machine, and for my users. To reproduce it I have launched my app while the integrated GPU is active, then launched and quit an app that requires the discrete GPU. One to five repetitions are required to create the hanging condition.

I believe the issue is triggered by my use of MigLayout, which results in the call to CGraphicsEnvironment as per this excerpt from the stack traces above:

at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)


PATCH

I believe the solution is to remember the main display ID along with the devices Map, and to change the main display ID when initDevices is called.
This appears to work in my setup. There is however _sometimes_ a flash of half-size rendering, presumably while the rendering is working on the old device
before the reconfiguration / initDevices occurs.

Below is a simple patch to demonstrate that approach. Generally I don’t think initDevices() should ever be called on the AWT-EventQueue, but in my tests (as per the comment)
that no longer happens with this patch.

diff -r 5dd7e4bae5c2 src/macosx/classes/sun/awt/CGraphicsEnvironment.java
--- a/src/macosx/classes/sun/awt/CGraphicsEnvironment.java Thu Sep 22 13:17:42 2016 -0700
+++ b/src/macosx/classes/sun/awt/CGraphicsEnvironment.java Sat Jan 07 20:49:39 2017 +1300
@@ -95,6 +95,7 @@

    /** Available CoreGraphics displays. */
    private final Map<Integer, CGraphicsDevice> devices = new HashMap<>(5);
+    private int inittedMainDisplayID;

    /** Reference to the display reconfiguration callback context. */
    private final long displayReconfigContext;
@@ -153,6 +154,7 @@
            devices.clear();

            int mainID = getMainDisplayID();
+            inittedMainDisplayID = mainID;

            // initialization of the graphics device may change
            // list of displays on hybrid systems via an activation
@@ -173,14 +175,13 @@

    @Override
    public synchronized GraphicsDevice getDefaultScreenDevice() throws HeadlessException {
-        final int mainDisplayID = getMainDisplayID();
-        CGraphicsDevice d = devices.get(mainDisplayID);
+        CGraphicsDevice d = devices.get(inittedMainDisplayID);
        if (d == null) {
            // we do not expect that this may happen, the only response
            // is to re-initialize the list of devices
            initDevices();

-            d = devices.get(mainDisplayID);
+            d = devices.get(inittedMainDisplayID);
            if (d == null) {
                throw new AWTError("no screen devices");
            }





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Re: [PATCH] Deadlock in CGLGraphicsConfig.getCGLConfigInfo

karlvr
Thanks Sergey,

I’m sorry I didn’t discover this bug somehow! Yes, this bug appears to be the exactly same fault:

We can see the Java2D Disposer thread blocked in the same spot as the AWT Event Queue thread was blocked in my examples, and for the same reason:

"Java2D Disposer" #1366 daemon prio=10 os_prio=31 tid=0x000000016859b800 nid=0xefeb runnable [0x000070000635a000] 
   java.lang.Thread.State: RUNNABLE 
at sun.java2d.opengl.CGLGraphicsConfig.getCGLConfigInfo(Native Method) 
at sun.java2d.opengl.CGLGraphicsConfig.getConfig(CGLGraphicsConfig.java:147) 
at sun.awt.CGraphicsDevice.<init>(CGraphicsDevice.java:64) 
at sun.awt.CGraphicsEnvironment.initDevices(CGraphicsEnvironment.java:167) 
- locked <0x000000044cbdce00> (a sun.awt.CGraphicsEnvironment) 
at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181) 

We can then see the main thread blocked trying to do the graphics device reconfiguration:

"main" #1 prio=6 os_prio=31 tid=0x0000000105811800 nid=0x160b waiting for monitor entry [0x00007fff5fbfb000] 
   java.lang.Thread.State: BLOCKED (on object monitor) 
at sun.awt.CGraphicsEnvironment._displayReconfiguration(CGraphicsEnvironment.java:129) 
- waiting to lock <0x000000044cbdce00> (a sun.awt.CGraphicsEnvironment) 
at org.eclipse.swt.internal.cocoa.OS.objc_msgSendSuper(Native Method) 
at org.eclipse.swt.widgets.Display.applicationNextEventMatchingMask(Display.java:5000) 
at org.eclipse.swt.widgets.Display.applicationProc(Display.java:5378) 

I believe my proposed patch will correct this issue as well, although I have not specifically reproduced this issue and tested the correction.

I don’t think I can comment on bug report itself (I don’t have a login). I have submitted an OCA and I am just waiting on that at the moment.

Once my OCA is confirmed I will send through the official review request. Thank you very much for the links to examples and information.

Best regards,
Karl




On 11/01/2017, at 9:42 AM, Sergey Bylokhov <[hidden email]> wrote:

Hi, Karl.

The correct alias to discuss this issue is 2d-dev.

Looks like this bug was reported before.

Your evaluation and the fix seems reasonable.
If you already signed the OCA[1] then you can send an official review request to 2d-dev. An example:  




I have encountered a deadlock in Java 1.8.0_112 when changing between discrete and integrated GPU on a retina MacBook Pro. The deadlock is between:

CGLGraphicsConfig.getCGLConfigInfo, running on AWT.EventQueue, trying to call [GraphicsConfigUtil _getCGLConfigInfo:] on
the main thread (AppKit thread) while it holds the AWT lock and is synchronized on CGraphicsEnvironment.

and

A) the AppKit main thread trying to call CGraphicsEnvironment._displayReconfiguration (via displaycb_handle in CGraphicsEnv.m)
and synchronizing on CGraphicsEnvironment—deadlock.

or

B) the AppKit main thread trying to render, and trying to acquire the OGLRenderQueue lock (which is the the AWT lock)


SUPPORTING STACK DUMPS

- SCENARIO A

CGraphicsEnvironment._displayReconfiguration is called on the main thread since
8041900: [macosx] Java forces the use of discrete GPU (https://bugs.openjdk.java.net/browse/JDK-8041900 <https://bugs.openjdk.java.net/browse/JDK-8041900>) which appears as changeset 11227.
In the native thread dump below you can see the frame for displaycb_handle which is the block dispatched to the main thread to call
CGraphicsEnvironment._displayReconfiguration.

Java stacks

"AWT-EventQueue-0" #16 prio=6 os_prio=31 tid=0x00007fbc72a0a800 nid=0x1251f runnable [0x000070000e443000]
  java.lang.Thread.State: RUNNABLE
at sun.java2d.opengl.CGLGraphicsConfig.getCGLConfigInfo(Native Method)
at sun.java2d.opengl.CGLGraphicsConfig.getConfig(CGLGraphicsConfig.java:147)
at sun.awt.CGraphicsDevice.<init>(CGraphicsDevice.java:64)
at sun.awt.CGraphicsEnvironment.initDevices(CGraphicsEnvironment.java:163)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)
[SNIP]
at java.awt.Container.layout(Container.java:1510)
at java.awt.Container.doLayout(Container.java:1499)
at java.awt.Container.validateTree(Container.java:1695)
[SNIP]
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1750)
[SNIP]
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

"AppKit Thread" #11 daemon prio=5 os_prio=31 tid=0x00007fbc75046800 nid=0x307 waiting for monitor entry [0x00007fff5b579000]
  java.lang.Thread.State: BLOCKED (on object monitor)
at sun.awt.CGraphicsEnvironment._displayReconfiguration(CGraphicsEnvironment.java:129)
- waiting to lock <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)

Native stacks

 Thread 0x6828c3           DispatchQueue 1           Thread name "AppKit Thread"                         1000 samples (1-1000)     priority 46 (base 46)     cpu time <0.001
 1000  start + 52 (Charles + 5156) [0x104682424]
   1000  main + 153 (Charles + 5321) [0x1046824c9]
     1000  launch + 10872 (Charles + 16520) [0x104685088]
       1000  JLI_Launch + 1952 (libjli.dylib + 5668) [0x104702624]
         1000  CreateExecutionEnvironment + 871 (libjli.dylib + 22781) [0x1047068fd]
           1000  CFRunLoopRunSpecific + 420 (CoreFoundation + 555380) [0x7fff97665974]
             1000  __CFRunLoopRun + 934 (CoreFoundation + 556918) [0x7fff97665f76]
               1000  __CFRunLoopDoSources0 + 557 (CoreFoundation + 559741) [0x7fff97666a7d]
                 1000  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 686465) [0x7fff97685981]
                   1000  __NSThreadPerformPerform + 326 (Foundation + 465034) [0x7fff990c988a]
                     1000  -[AWTStarter starter:] + 905 (libawt_lwawt.dylib + 286207) [0x113081dff]
                       1000  +[NSApplicationAWT runAWTLoopWithApp:] + 156 (libosxapp.dylib + 8525) [0x1130fa14d]
[SNIP]
                                                 1000  +[JNFRunLoop _performCopiedBlock:] + 17 (JavaNativeFoundation + 28474) [0x112d0df3a]
                                                   1000  __displaycb_handle_block_invoke_1 + 172 (libawt_lwawt.dylib + 119659) [0x11305936b]
                                                     1000  JNFPerformEnvBlock + 87 (JavaNativeFoundation + 27229) [0x112d0da5d]
                                                       1000  __displaycb_handle_block_invoke_2 + 80 (libawt_lwawt.dylib + 119988) [0x1130594b4]
                                                         1000  JNFCallVoidMethod + 187 (JavaNativeFoundation + 13743) [0x112d0a5af]
                                                           1000  jni_CallVoidMethodV + 248 (libjvm.dylib + 3069241) [0x106301539]
                                                             1000  jni_invoke_nonstatic(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) + 748 (libjvm.dylib + 3124227) [0x10630ec03]
                                                               1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x1062f4396]
                                                                 1000  ??? [0x113db94e7]
                                                                   1000  ??? [0x113dde021]
                                                                     1000  InterpreterRuntime::monitorenter(JavaThread*, BasicObjectLock*) + 165 (libjvm.dylib + 2995347) [0x1062ef493]
                                                                       1000  ObjectMonitor::enter(Thread*) + 472 (libjvm.dylib + 4524724) [0x106464ab4]
                                                                         1000  ObjectMonitor::EnterI(Thread*) + 532 (libjvm.dylib + 4521584) [0x106463e70]
                                                                           1000  os::PlatformEvent::park(long) + 404 (libjvm.dylib + 4561328) [0x10646d9b0]
                                                                             1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                              *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]

 Thread 0x68292c           Thread name "Java: AWT-EventQueue-0"                1000 samples (1-1000)     priority 31 (base 31)
 1000  thread_start + 13 (libsystem_pthread.dylib + 12797) [0x7fffacdd51fd]
   1000  _pthread_start + 286 (libsystem_pthread.dylib + 14839) [0x7fffacdd59f7]
     1000  _pthread_body + 180 (libsystem_pthread.dylib + 15019) [0x7fffacdd5aab]
       1000  java_start(Thread*) + 246 (libjvm.dylib + 4574506) [0x106470d2a]
         1000  JavaThread::run() + 448 (libjvm.dylib + 5486408) [0x10654f748]
           1000  JavaThread::thread_main_inner() + 155 (libjvm.dylib + 5480593) [0x10654e091]
             1000  thread_entry(JavaThread*, Thread*) + 124 (libjvm.dylib + 3270354) [0x1063326d2]
               1000  JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*) + 74 (libjvm.dylib + 3017936) [0x1062f4cd0]
                 1000  JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*) + 356 (libjvm.dylib + 3017508) [0x1062f4b24]
                   1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x1062f4396]
[SNIP]
                                                                                           1000  Java_sun_java2d_opengl_CGLGraphicsConfig_getCGLConfigInfo + 279 (libawt_lwawt.dylib + 107562) [0x11305642a]
                                                                                             1000  -[NSObject(NSThreadPerformAdditions) performSelectorOnMainThread:withObject:waitUntilDone:] + 131 (Foundation + 203394) [0x7fff99089a82]
                                                                                               1000  -[NSObject(NSThreadPerformAdditions) performSelector:onThread:withObject:waitUntilDone:modes:] + 904 (Foundation + 204424) [0x7fff99089e88]
                                                                                                 1000  -[NSCondition wait] + 240 (Foundation + 208331) [0x7fff9908adcb]
                                                                                                   1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                                                    *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]






- Scenario B

Java stacks

"AWT-EventQueue-0" #15 prio=6 os_prio=31 tid=0x00007fba611d2000 nid=0x1260f runnable [0x0000700005365000]
  java.lang.Thread.State: RUNNABLE
at sun.java2d.opengl.CGLGraphicsConfig.getCGLConfigInfo(Native Method)
at sun.java2d.opengl.CGLGraphicsConfig.getConfig(CGLGraphicsConfig.java:147)
at sun.awt.CGraphicsDevice.<init>(CGraphicsDevice.java:64)
at sun.awt.CGraphicsEnvironment.initDevices(CGraphicsEnvironment.java:163)
- locked <0x00000006c0df8c18> (a sun.awt.CGraphicsEnvironment)
at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0df8c18> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)
at net.miginfocom.layout.UnitValue.getPixelsExact(UnitValue.java:305)
at net.miginfocom.layout.UnitValue.getPixels(UnitValue.java:281)
[SNIP]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

"AppKit Thread" #11 daemon prio=5 os_prio=31 tid=0x00007fba59869800 nid=0x307 waiting on condition [0x00007fff52ac2000]
  java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for  <0x00000006c053b688> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:870)
at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1199)
at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:209)
at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:285)
at sun.awt.SunToolkit.awtLock(SunToolkit.java:253)
at sun.java2d.pipe.RenderQueue.lock(RenderQueue.java:112)
at sun.java2d.opengl.CGLLayer.drawInCGLContext(CGLLayer.java:139)

Native stacks

 Thread 0x6764ca           DispatchQueue 1           Thread name "AppKit Thread"                         1000 samples (1-1000)     priority 46 (base 46)
 1000  start + 52 (Charles + 5156) [0x10d139424]
   1000  main + 153 (Charles + 5321) [0x10d1394c9]
     1000  launch + 10872 (Charles + 16520) [0x10d13c088]
       1000  JLI_Launch + 1952 (libjli.dylib + 5668) [0x10d1b9624]
         1000  CreateExecutionEnvironment + 871 (libjli.dylib + 22781) [0x10d1bd8fd]
           1000  CFRunLoopRunSpecific + 420 (CoreFoundation + 555380) [0x7fff97665974]
             1000  __CFRunLoopRun + 934 (CoreFoundation + 556918) [0x7fff97665f76]
               1000  __CFRunLoopDoSources0 + 557 (CoreFoundation + 559741) [0x7fff97666a7d]
                 1000  __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 (CoreFoundation + 686465) [0x7fff97685981]
                   1000  __NSThreadPerformPerform + 326 (Foundation + 465034) [0x7fff990c988a]
                     1000  -[AWTStarter starter:] + 905 (libawt_lwawt.dylib + 286207) [0x12abc3dff]
                       1000  +[NSApplicationAWT runAWTLoopWithApp:] + 156 (libosxapp.dylib + 8525) [0x12ac3c14d]
[SNIP]
                                             1000  CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 108 (QuartzCore + 69522) [0x7fff9d393f92]
                                               1000  CA::Transaction::commit() + 475 (QuartzCore + 67121) [0x7fff9d393631]
                                                 1000  CA::Context::commit_transaction(CA::Transaction*) + 280 (QuartzCore + 1153144) [0x7fff9d49c878]
                                                   1000  CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 35 (QuartzCore + 1196185) [0x7fff9d4a7099]
                                                     1000  CA::Layer::display_if_needed(CA::Transaction*) + 572 (QuartzCore + 1195886) [0x7fff9d4a6f6e]
                                                       1000  -[CAOpenGLLayer _display] + 351 (QuartzCore + 1117583) [0x7fff9d493d8f]
                                                         1000  CAOpenGLLayerDraw(CAOpenGLLayer*, double, CVTimeStamp const*, unsigned int) + 873 (QuartzCore + 1118737) [0x7fff9d494211]
                                                           1000  -[CGLLayer drawInCGLContext:pixelFormat:forLayerTime:displayTime:] + 287 (libawt_lwawt.dylib + 109022) [0x12ab989de]
                                                             1000  JNFCallVoidMethod + 187 (JavaNativeFoundation + 13743) [0x12a84f5af]
                                                               1000  jni_CallVoidMethodV + 248 (libjvm.dylib + 3069241) [0x10edb8539]
                                                                 1000  jni_invoke_nonstatic(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) + 748 (libjvm.dylib + 3124227) [0x10edc5c03]
                                                                   1000  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) + 1710 (libjvm.dylib + 3015574) [0x10edab396]
                                                                     1000  ??? [0x10ffa0854]
                                                                       1000  ??? [0x11027642a]
                                                                         1000  Unsafe_Park + 126 (libjvm.dylib + 5571927) [0x10f01b557]
                                                                           1000  Parker::park(bool, long) + 495 (libjvm.dylib + 4560765) [0x10ef2477d]
                                                                             1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                              *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]

 Thread 0x67652b           Thread name "Java: AWT-EventQueue-0"                1000 samples (1-1000)     priority 31 (base 31)
 1000  thread_start + 13 (libsystem_pthread.dylib + 12797) [0x7fffacdd51fd]
   1000  _pthread_start + 286 (libsystem_pthread.dylib + 14839) [0x7fffacdd59f7]
     1000  _pthread_body + 180 (libsystem_pthread.dylib + 15019) [0x7fffacdd5aab]
       1000  java_start(Thread*) + 246 (libjvm.dylib + 4574506) [0x10ef27d2a]
         1000  JavaThread::run() + 448 (libjvm.dylib + 5486408) [0x10f006748]
           1000  JavaThread::thread_main_inner() + 155 (libjvm.dylib + 5480593) [0x10f005091]
             1000  thread_entry(JavaThread*, Thread*) + 124 (libjvm.dylib + 3270354) [0x10ede96d2]
[SNIP]
                                                                                           1000  ??? [0x10f7a0734]
                                                                                             1000  Java_sun_java2d_opengl_CGLGraphicsConfig_getCGLConfigInfo + 279 (libawt_lwawt.dylib + 107562) [0x12ab9842a]
                                                                                               1000  -[NSObject(NSThreadPerformAdditions) performSelectorOnMainThread:withObject:waitUntilDone:] + 131 (Foundation + 203394) [0x7fff99089a82]
                                                                                                 1000  -[NSObject(NSThreadPerformAdditions) performSelector:onThread:withObject:waitUntilDone:modes:] + 904 (Foundation + 204424) [0x7fff99089e88]
                                                                                                   1000  -[NSCondition wait] + 240 (Foundation + 208331) [0x7fff9908adcb]
                                                                                                     1000  __psynch_cvwait + 10 (libsystem_kernel.dylib + 105606) [0x7fffaccecc86]
                                                                                                      *1000  psynch_cvcontinue + 0 (pthread + 39138) [0xffffff7f80f978e2]


INTERPRETATION

The deadlock is a race condition when macOS changes between the discrete and integrated GPU.

When the GPU changes, the result of CGraphicsEnvironment.getMainDisplayID() changes immediately (There is a comment in CGraphicsEnvironment.m
that notes that the display ID changes in this case, and I have verified this) to return the new displayID, while the devices map is only built once initDevices() is called.

CGLGraphicsConfig.getCGLConfigInfo (which is called as a consequence of initDevices, as per stack traces) calls out and waits on the AppKit main thread. I think this is
always dangerous due to the locks that the code calling it holds. I think we should avoid getCGLConfigInfo being called on anything but the AppKit main thread. I believe
this was the intention of 8041900: [macosx] Java forces the use of discrete GPU (https://bugs.openjdk.java.net/browse/JDK-8041900 <https://bugs.openjdk.java.net/browse/JDK-8041900>).

CGraphicsEnvironment.getDefaultScreenDevice() is called from AWT layout code (as per the stacks) and it calls CGraphicsEnvironment.getMainDisplayID() each time.
If CGraphicsEnvironment.getDefaultScreenDevice() is called _after_ the GPU change, but _before_ CGraphicsEnvironment._displayReconfiguration() has been called,
the CGraphicsDevice for the new display ID cannot be found in the devices Map, so initDevices() is called from CGraphicsEnvironment.getDefaultScreenDevice()
on the AWT-EventQueue thread.

There is a note in getDefaultScreenDevice() for this case:
   we do not expect that this may happen, the only response is to re-initialize the list of devices

Calling initDevices() here results in a call to CGLGraphicsConfig.getCGLConfigInfo, which then calls
[GraphicsConfigUtil _getCGLConfigInfo:] on the AppKit main thread and waits for the result.

As the current thread (AWT Event queue) is holding the AWT lock, and is synchronized on CGraphicsEnvironment, the two deadlock
conditions described above can occur.


REPRODUCABILITY

This happens quite regularly on my machine, and for my users. To reproduce it I have launched my app while the integrated GPU is active, then launched and quit an app that requires the discrete GPU. One to five repetitions are required to create the hanging condition.

I believe the issue is triggered by my use of MigLayout, which results in the call to CGraphicsEnvironment as per this excerpt from the stack traces above:

at sun.awt.CGraphicsEnvironment.getDefaultScreenDevice(CGraphicsEnvironment.java:181)
- locked <0x00000006c0721bb0> (a sun.awt.CGraphicsEnvironment)
at sun.lwawt.macosx.LWCToolkit.getScreenResolution(LWCToolkit.java:415)
at net.miginfocom.swing.SwingComponentWrapper.getHorizontalScreenDPI(SwingComponentWrapper.java:260)
at net.miginfocom.swing.SwingComponentWrapper.getPixelUnitFactor(SwingComponentWrapper.java:119)


PATCH

I believe the solution is to remember the main display ID along with the devices Map, and to change the main display ID when initDevices is called.
This appears to work in my setup. There is however _sometimes_ a flash of half-size rendering, presumably while the rendering is working on the old device
before the reconfiguration / initDevices occurs.

Below is a simple patch to demonstrate that approach. Generally I don’t think initDevices() should ever be called on the AWT-EventQueue, but in my tests (as per the comment)
that no longer happens with this patch.

diff -r 5dd7e4bae5c2 src/macosx/classes/sun/awt/CGraphicsEnvironment.java
--- a/src/macosx/classes/sun/awt/CGraphicsEnvironment.java Thu Sep 22 13:17:42 2016 -0700
+++ b/src/macosx/classes/sun/awt/CGraphicsEnvironment.java Sat Jan 07 20:49:39 2017 +1300
@@ -95,6 +95,7 @@

    /** Available CoreGraphics displays. */
    private final Map<Integer, CGraphicsDevice> devices = new HashMap<>(5);
+    private int inittedMainDisplayID;

    /** Reference to the display reconfiguration callback context. */
    private final long displayReconfigContext;
@@ -153,6 +154,7 @@
            devices.clear();

            int mainID = getMainDisplayID();
+            inittedMainDisplayID = mainID;

            // initialization of the graphics device may change
            // list of displays on hybrid systems via an activation
@@ -173,14 +175,13 @@

    @Override
    public synchronized GraphicsDevice getDefaultScreenDevice() throws HeadlessException {
-        final int mainDisplayID = getMainDisplayID();
-        CGraphicsDevice d = devices.get(mainDisplayID);
+        CGraphicsDevice d = devices.get(inittedMainDisplayID);
        if (d == null) {
            // we do not expect that this may happen, the only response
            // is to re-initialize the list of devices
            initDevices();

-            d = devices.get(mainDisplayID);
+            d = devices.get(inittedMainDisplayID);
            if (d == null) {
                throw new AWTError("no screen devices");
            }






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Re: [PATCH] Deadlock in CGLGraphicsConfig.getCGLConfigInfo

Hendrik Schreiber

> On Jan 12, 2017, at 04:22, Karl von Randow <[hidden email]> wrote:
>
> I’m sorry I didn’t discover this bug somehow!

Who cares?—I really appreciate that you provide a fix after no progress has been made for more than half a year!

That’s awesome.

-hendrik

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Re: [PATCH] Deadlock in CGLGraphicsConfig.getCGLConfigInfo

Hendrik Schreiber
Hey there,

just curious regarding the state of this bug.

@Karl: Did someone review your patch? Or did you gain any additional support for submitting it?

It would be a shame to not incorporate the fix, just because it was simply forgotten…

-hendrik

> On Jan 12, 2017, at 08:58, Hendrik Schreiber <[hidden email]> wrote:
>
>
>> On Jan 12, 2017, at 04:22, Karl von Randow <[hidden email]> wrote:
>>
>> I’m sorry I didn’t discover this bug somehow!
>
> Who cares?—I really appreciate that you provide a fix after no progress has been made for more than half a year!
>
> That’s awesome.
>
> -hendrik
>

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