<AWT Dev> <Awt Dev> [9] Review Request for 8132664: closed/javax/swing/DataTransfer/DefaultNoDrop/DefaultNoDrop.java locks on Windows

Sergey Bylokhov Sergey.Bylokhov at oracle.com
Wed Aug 5 11:33:00 UTC 2015

On 05.08.15 14:20, Semyon Sadetsky wrote:
> On 8/5/2015 1:39 PM, Sergey Bylokhov wrote:
>> On 05.08.15 13:18, Semyon Sadetsky wrote:
>>> On 8/5/2015 12:27 PM, Sergey Bylokhov wrote:
>>>> On 04.08.15 14:54, Semyon Sadetsky wrote:
>>>>> On 8/3/2015 6:05 PM, Sergey Bylokhov wrote:
>>>>>> Hi, Semyon
>>>>>> Did you try to change dwMilliseconds from INFINITE to the 
>>>>>> timeout(10 seconds by default?) which is passed to the method? It 
>>>>>> does not help? Because even when dnd is not used we should not 
>>>>>> wait event for infinite time.
>>>>> It would not help to fix the issue because 10 seconds is too big 
>>>>> interval. But for consistency it is not bad to have a time limit.
>>>>> http://cr.openjdk.java.net/~ssadetsky/8132664/webrev.01/
>>>> Note that syncNativeQueue is intended to wait until the native 
>>>> event queue is flushed or until timeout will expire. So even if 
>>>> timeout is expired we collect the native events during this period 
>>>> of time.Can you double check that the event counter is incremented 
>>>> during dnd? I do not know how we block the toolkit thread, probably 
>>>> we create some nested loops which ignore our event posted from 
>>>> syncNativeQueue, can we change that?
>>> Yes, this is an internal secondary loop which waits for mouse 
>>> release event.
>> Can we change the condition and process the sync event in this loop?
> Why? Will receive all events on the toolkit thread when doDragDrop 
> returns.

When how we get dragenter/exit events?

>>> Event counter is not changed during toolkit thread blocking of 
>>> cause. Not sure that we can change that. But since toolkit queue is 
>>> blocked we can assume that we are synced.
>>>> The timeout value is maintained on the shared level and actually 
>>>> this test will fail with timeout on osx as well JDK-7185258. The 
>>>> test will fail even if the time out will be changed to ±100ms, 
>>>> because it call realsync on each pixel move, ±200 times. This 
>>>> problem can be fixed in different ways like tweak of timeouts and 
>>>> numbers of iterations, or changing the test to call w4idle only 
>>>> after the latest move(actually I think this method can be moved to 
>>>> the robot class).
>>>> So I still think that the right fix for a deadlock, which is 
>>>> subject of this bug, is simply change the syncNativeQueue and waits 
>>>> using a timeout if it is positive, and waits forever if timeout is 
>>>> negative (the same bug on osx JDK-8080504).
>>> I'm not sure that waiting brings any value. What do you propose to 
>>> return if it timed out? The event counter will not be changed 
>>> regardless of waiting.
>> But it should be changed, because we get native events from the 
>> system during dnd and in each such callback we should update this 
>> counter. If callbacks were not called=>counter was not updated then 
>> sync assume that currently we do not process events. If callbacks 
>> were called then sync assume that we have events in the native queue 
>> and should try to sync again on the next iteration.
> No. Events are not processed while toolkit is blocked in doDragDrop(). 
> The application state is frozen on that period. That is Windows approach.
>>> With such waiting the test will fail because of either jtreg timeout
>> Default timeout is 120 seconds for everything, the test try to sync 
>> the queue 200 of times after each move, so yes it can fail with 
>> timeout even if spend in nativesync 200 ms, the possible solutions 
>> were in my previous email.
>>> either InfiniteLoop exception.
>> This exception will be disabled by default lately in jdk9 timeframe, 
>> right now it helps to find some related issues.
>>>>>> On 03.08.15 17:26, Semyon Sadetsky wrote:
>>>>>>> Hello,
>>>>>>> Please review fix for JDK9:
>>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8132664
>>>>>>> webrev: http://cr.openjdk.java.net/~ssadetsky/8132664/webrev.00/
>>>>>>> DoDragDrop() is blocking, so upon drag operation is triggered 
>>>>>>> the toolkit thread is blocked and the WM_AWT_WAIT cannot be 
>>>>>>> processed which in its turn blocks the AWT robot.
>>>>>>> The solution is to escape AWT robot waiting in syncNativeQueue() 
>>>>>>> if drag operation is in progress.
>>>>>>> --Semyon

Best regards, Sergey.

More information about the awt-dev mailing list