4913324: Deadlock when using two event queues

Reviewed-by: anthony, ant, dcherepanov

jdk/src/share/classes/java/awt/EventDispatchThread.java

@@ -104,11 +104,8 @@ class EventDispatchThread extends Thread {
         } else {
             stopEvent.dispatch();
         }
-        synchronized (theQueue) {
-            if (theQueue.getDispatchThread() == this) {
-                theQueue.detachDispatchThread();
-            }
-        }
+
+        theQueue.detachDispatchThread(this, false);
     }
 
     public void stopDispatching() {
@@ -142,35 +139,7 @@ class EventDispatchThread extends Thread {
                 }
             });
         } finally {
-            /*
-             * This synchronized block is to secure that the event dispatch
-             * thread won't die in the middle of posting a new event to the
-             * associated event queue. It is important because we notify
-             * that the event dispatch thread is busy after posting a new event
-             * to its queue, so the EventQueue.dispatchThread reference must
-             * be valid at that point.
-             */
-            synchronized (theQueue) {
-                if (theQueue.getDispatchThread() == this) {
-                    theQueue.detachDispatchThread();
-                }
-                /*
-                 * Event dispatch thread dies in case of an uncaught exception.
-                 * A new event dispatch thread for this queue will be started
-                 * only if a new event is posted to it. In case if no more
-                 * events are posted after this thread died all events that
-                 * currently are in the queue will never be dispatched.
-                 */
-                /*
-                 * Fix for 4648733. Check both the associated java event
-                 * queue and the PostEventQueue.
-                 */
-                if (theQueue.peekEvent() != null ||
-                    !SunToolkit.isPostEventQueueEmpty()) {
-                    theQueue.initDispatchThread();
-                }
-                AWTAutoShutdown.getInstance().notifyThreadFree(this);
-            }
+            theQueue.detachDispatchThread(this, true);
         }
     }
 

jdk/src/share/classes/sun/awt/AWTAccessor.java

@@ -248,14 +248,14 @@ public final class AWTAccessor {
      * An accessor for the EventQueue class
      */
     public interface EventQueueAccessor {
-        /*
-         * Gets the next event queue.
-         */
-        EventQueue getNextQueue(EventQueue eventQueue);
         /*
          * Gets the event dispatch thread.
          */
         Thread getDispatchThread(EventQueue eventQueue);
+        /*
+         * Checks if the current thread is EDT for the given EQ.
+         */
+        public boolean isDispatchThreadImpl(EventQueue eventQueue);
     }
 
     /*

jdk/src/share/classes/sun/awt/AppContext.java

@@ -43,6 +43,9 @@ import java.util.HashSet;
 import java.beans.PropertyChangeSupport;
 import java.beans.PropertyChangeListener;
 import sun.util.logging.PlatformLogger;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * The AppContext is a table referenced by ThreadGroup which stores
@@ -132,10 +135,17 @@ public final class AppContext {
     /* Since the contents of an AppContext are unique to each Java
      * session, this class should never be serialized. */
 
-    /* The key to put()/get() the Java EventQueue into/from the AppContext.
+    /*
+     * The key to put()/get() the Java EventQueue into/from the AppContext.
      */
     public static final Object EVENT_QUEUE_KEY = new StringBuffer("EventQueue");
 
+    /*
+     * The keys to store EventQueue push/pop lock and condition.
+     */
+    public final static Object EVENT_QUEUE_LOCK_KEY = new StringBuilder("EventQueue.Lock");
+    public final static Object EVENT_QUEUE_COND_KEY = new StringBuilder("EventQueue.Condition");
+
     /* A map of AppContexts, referenced by ThreadGroup.
      */
     private static final Map<ThreadGroup, AppContext> threadGroup2appContext =
@@ -244,6 +254,13 @@ public final class AppContext {
                         return Thread.currentThread().getContextClassLoader();
                     }
                 });
+
+        // Initialize push/pop lock and its condition to be used by all the
+        // EventQueues within this AppContext
+        Lock eventQueuePushPopLock = new ReentrantLock();
+        put(EVENT_QUEUE_LOCK_KEY, eventQueuePushPopLock);
+        Condition eventQueuePushPopCond = eventQueuePushPopLock.newCondition();
+        put(EVENT_QUEUE_COND_KEY, eventQueuePushPopCond);
     }
 
     private static final ThreadLocal<AppContext> threadAppContext =

jdk/src/share/classes/sun/awt/SunToolkit.java

@@ -722,13 +722,7 @@ public abstract class SunToolkit extends Toolkit
         EventQueue eq = (EventQueue)appContext.get(AppContext.EVENT_QUEUE_KEY);
 
         AWTAccessor.EventQueueAccessor accessor = AWTAccessor.getEventQueueAccessor();
-        EventQueue next = accessor.getNextQueue(eq);
-        while (next != null) {
-            eq = next;
-            next = accessor.getNextQueue(eq);
-        }
-
-        return (Thread.currentThread() == accessor.getDispatchThread(eq));
+        return accessor.isDispatchThreadImpl(eq);
     }
 
     public Dimension getScreenSize() {

jdk/test/java/awt/EventQueue/PushPopDeadlock2/PushPopTest.java

+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+  @test
+  @bug 4913324
+  @author Oleg Sukhodolsky: area=eventqueue
+  @run main/timeout=30 PushPopTest
+*/
+
+import java.awt.*;
+import java.awt.event.*;
+import java.util.EmptyStackException;
+import sun.awt.SunToolkit;
+
+public class PushPopTest {
+
+    public static Frame frame;
+    public static void main(String[] args) {
+        frame = new Frame("");
+        frame.pack();
+
+        Runnable dummy = new Runnable() {
+                public void run() {
+                    System.err.println("Dummy is here.");
+                }
+            };
+        EventQueue seq = Toolkit.getDefaultToolkit().getSystemEventQueue();
+        MyEventQueue1 eq1 = new MyEventQueue1();
+        MyEventQueue2 eq2 = new MyEventQueue2();
+        EventQueue.invokeLater(dummy);
+
+        seq.push(eq1);
+        EventQueue.invokeLater(dummy);
+
+        eq1.push(eq2);
+        EventQueue.invokeLater(dummy);
+        Runnable runnable = new Runnable() {
+                public void run() {
+                    System.err.println("Dummy from SunToolkit");
+                }
+            };
+        InvocationEvent ie = new InvocationEvent(eq2, runnable, null, false);
+        System.err.println(ie);
+        SunToolkit.postEvent(SunToolkit.targetToAppContext(frame), ie);
+        eq1.pop();
+        frame.dispose();
+    }
+}
+
+class MyEventQueue1 extends EventQueue {
+
+    public void pop() throws EmptyStackException {
+        super.pop();
+    }
+}
+
+class MyEventQueue2 extends EventQueue {
+
+    protected void pop() throws EmptyStackException {
+        System.err.println("pop2()");
+        Thread.dumpStack();
+        try {
+            EventQueue.invokeAndWait(new Runnable() {
+                    public void run() {
+                        Runnable runnable = new Runnable() {
+                                public void run() {
+                                    System.err.println("Dummy from here");
+                                }
+                             };
+                        InvocationEvent ie = new InvocationEvent(MyEventQueue2.this, runnable, null, false);
+                        SunToolkit.postEvent(SunToolkit.targetToAppContext(PushPopTest.frame), ie);
+                        postEvent(ie);
+                    }
+                });
+        } catch (InterruptedException ie) {
+            ie.printStackTrace();
+        } catch (java.lang.reflect.InvocationTargetException ie) {
+            ie.printStackTrace();
+        }
+        super.pop();
+    }
+}