<AWT Dev> [9] Review request for 8031694: [macosx] TwentyThousandTest test intermittently hangs

Oleg Pekhovskiy oleg.pekhovskiy at oracle.com
Fri Feb 7 08:18:01 PST 2014

Hi Anthony,

there are two points for choosing this solution:
1. If something makes EDT to die, there is a serious reason to do so. 
It's a forced action.
So it should be done ASAP. Dying EDT usage for pumping followed events 
looks strange because we expect him to die.
Moreover it could happen that events are posted quite frequently to keep 
dying EDT alive for some period of time.

2. Synchronization object for posting events from different threads is 
it is used in EventQueue. postEventPrivate(), EventQueue.getNextEvent() 
and EventQueue. detachDispatchThread().
When dying EDT returns from EventDispatchThread.pumpEventsForFilter() to 
EventDispatchThread.run() and then goes to
getEventQueue().detachDispatchThread(), EventQueue.pushPopLock is not 
used, so any other thread could post events.
So if we don't call peekEvent() to recreate a new EDT, we'll just loose 
these events as it currently happens.

So the main idea is to make EDT life cycle phases obvious.


On 02/07/2014 06:48 PM, Anthony Petrov wrote:
> Hi Oleg,
> This code is very tricky. I like it that we process any events that 
> might be posted to the queue after the current EDT dies. However, 
> could you please clarify how initializing a new EDT is any different 
> from not letting the old one die? I.e. could we just not kill the old 
> EDT if we see there are more events in the queue? If not, what exact 
> difference does you solution bring?
> It's not that I'm against your fix, it looks good actually. I'd just 
> like to understand the difference. Please elaborate.
> Also, I recall we've fixed a number of bugs in this area. Are we sure 
> we don't regress after this fix?
> -- 
> best regards,
> Anthony
> On 2/7/2014 4:31 AM, Oleg Pekhovskiy wrote:
>> Hi all,
>> please review the next version of fix:
>> http://cr.openjdk.java.net/~bagiras/8031694.2/
>> We with Artem Ananiev had off-line discussion and he offered let the
>> dying EDT to die
>> and process unhandled events by forcing another EDT start.
>> Thanks,
>> Oleg
>> On 01/28/2014 05:32 AM, Oleg Pekhovskiy wrote:
>>> Hi all,
>>> please review the fix
>>> http://cr.openjdk.java.net/~bagiras/8031694.1/
>>> for
>>> https://bugs.openjdk.java.net/browse/JDK-8031694
>>> During forward-port of JDK-7189350 EDT.doDispatch was not taken into
>>> account when calling EventQueue.detachDispatchThread().
>>> As a result harmful optimization of this method occurred.
>>> So when doDispatch became false, no more events in QventQueue were
>>> handled before EDT shutdown.
>>> I kept the optimization but added the check to
>>> EDT.pumpEventsForFilter() that EventQueue is not empty to keep pumping.
>>> Thanks,
>>> Oleg

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