Re: [7u8] Review request for 7177040: Deadlock between PostEventQueue.noEvents, EventQueue.isDispatchThread and SwingUtilities.invokeLater

[Oleg Pekhovskiy]

Hi David,

it's thread-safe indirectly. SunToolkit.flushPendingEvents() & 
SunToolkitSubclass.flushPendingEvents() are the only methods that call 
PostEventQueue.flush().
They both have flushLock synchronization object that guarantees 
synchronized call of PostEventQueue.flush().

Thanks,
Oleg

7/26/2012 4:08 PM, David Holmes wrote:
This fix still makes me uncomfortable because flush() is not 
thread-safe any more. If two threads can flush() then the first can 
clear the isFlushing state (in the finally block) that has been set by 
the second (in the synchronized block).

David

On 24/07/2012 9:42 PM, Peter Levart wrote:
Hi Oleg,

This is just cosmetics, but:

SunToolkit:
public synchronized boolean noEvents() {
         return queueHead == null && !isFlushing;
     }

... a thread calling noEvents could see occasional "spikes" of false
return even though there is no flushing being performed (when other
thread is calling flush on an empty PostEventQueue).

Improved flush method would look like this:

     public void flush() {
         EventQueueItem tempQueue;
         synchronized (this) {
             tempQueue = queueHead;
             queueHead = queueTail = null;
             isFlushing =*/(tempQueue != null)/*;

         }
         try {
             while (tempQueue != null) {
                 eventQueue.postEvent(tempQueue.event);
                 tempQueue = tempQueue.next;
             }
         }
         finally {
             isFlushing = false;
         }
     }


Regards, Peter

2012/7/23 Oleg Pekhovskiy <oleg.pekhovs...@oracle.com
<mailto:oleg.pekhovs...@oracle.com>>

    Hi!

    Please review this back-port being already pushed to jdk8 but
    deferred for 7u6.

    Bug:
    http://bugs.sun.com/view_bug.__do?bug_id=7177040
<http://bugs.sun.com/view_bug.do?bug_id=7177040>

    Webrev:
    http://cr.openjdk.java.net/~__bagiras/7u8/7177040.1
<http://cr.openjdk.java.net/~bagiras/7u8/7177040.1>

    Review thread for 7u6:
    
http://mail.openjdk.java.net/__pipermail/awt-dev/2012-July/__003106.html
<http://mail.openjdk.java.net/pipermail/awt-dev/2012-July/003106.html>

    Reviewers 7u6 & 8:
    Anthony Petrov, Anton Tarasov

    Thanks,
    Oleg