Hi Anthony,
I see your concerns.
As PostEventQueue.flush() method left unsynchronized,
we potentially could return PostEventQueue.noEvents()
and return check in EventQueue.detachDispatchThread()
back to the condition.
But is could increase the possibility of deadlock in future
(with PostEventQueue & pushPopLock).
Artem, what do you think?
Thanks,
Oleg
29.08.2012 15:22, Anthony Petrov wrote:
On 8/29/2012 3:08 PM, Anthony Petrov wrote:
Hi Oleg,
I'm still concerned about the following:
detachDispatchThread()
{
flush();
lock();
// possibly detach
unlock();
}
at EventQueue.java. What if an even get posted to the queue after the
A typo: s/even get/event gets/.
--
best regards,
Anthony
flush() returns but before we even acquired the lock? We may still
end up with a situation when we detach the thread while in fact there
are some pending events present, which actually contradicts the
current logic of the detach() method. I see that you say "Minimize
discard possibility" in the comment instead of "Prevent ...", but I
feel uncomfortable with this actually.
What exactly prevents us from adding some synchronization to ensure
that the detaching only happens when there's really no pending events?
SunToolkit.java:
2120 Boolean b = isThreadLocalFlushing.get();
2121 if (b != null && b) {
2122 return;
2123 }
2124 2125 isThreadLocalFlushing.set(true);
2126 try {
How does access to the isThreadLocalFlushing synchronized? What
happens if the flush() is being invoked from two different threads
for the same post event queue? Why do we have two "isFlushing" flags?
Can we collapse them into one? Why is the isFlushing set/reset in two
disjunct synchronized(){} blocks?
Overall, I find the current synchronization scheme in flush() very,
*very* (and I mean it) confusing. Can we simplify it somehow?
--
best regards,
Anthony
On 8/28/2012 6:33 PM, Oleg Pekhovskiy wrote:
Hi Artem, Anthony,
thank you for your proposals!
We with Artem also had off-line discussion,
so as a result I prepared improved version of fix:
http://cr.openjdk.java.net/~bagiras/8/7186109.3/
What was done:
1. EventQueue.detachDispatchThread(): moved
SunToolkit.flushPnedingEvents() above the comments and added a
separate comment to it.
2. Moved SunToolkitSubclass.flushPendingEvents(AppContext) method to
SunToolkit. Deleted SunToolkitSubclass.
3. Moved isFlushingPendingEvents to PostEventQueue with the new name
- isThreadLocalFlushing and made it ThreadLocal.
4. Left PostEventQueue.flush() unsynchronized and created
wait()-notifyAll() synchronization mechanism to avoid blocking of
PostEventQueue.postEvent().
Looking forward to your comments!
Thanks,
Oleg
20.08.2012 20:20, Artem Ananiev wrote:
Hi, Oleg,
here are a few comments:
1. What is the reason of keeping "isFlushingPendingEvents" in
SunToolkit, given that PEQ.flush() is synchronized (and therefore
serialized) anyway?
2. flushPendingEvents(AppContext) may be moved directly to
SunToolkit, so we don't need a separate sun-class for that.
3. EQ.java:1035-1040 - this comment is obsolete and must be
replaced by another one.
Thanks,
Artem
On 8/17/2012 4:49 PM, Oleg Pekhovskiy wrote:
Hi!
Please review the fix for CR:
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7186109
Webrev:
http://cr.openjdk.java.net/~bagiras/8/7186109.1/
The following changes were made:
1. Removed flushLock from SunToolkit.flushPendingEvent()
2. Returned method PostEventQueue.flush() as 'synchronized' back
3. Added call of SunToolkit.flushPendingEvents() to
EventQueue.detachDispatchThread(),
right before pushPopLock.lock()
4. Removed !SunToolkit.isPostEventQueueEmpty() check from
EventQueue.detachDispatchThread()
5. Removed SunToolkit.isPostEventQueueEmpty() &
PostEventQueue.noEvents();
Thanks,
Oleg
<http://cr.openjdk.java.net/%7Ebagiras/8/7186109.1/>
