<AWT Dev> [11][JDK-8152974] AWT hang occurs when sequenced events

Fri Mar 16 17:43:21 UTC 2018

On 16/03/2018 08:42, semyon.sadetsky at oracle.com wrote:
>> That's funny. And who gave you such strong confidence? Sergey? to whom 
>> you are so grateful?
>> I'd better ask him for other ideas because the change should never go 
>> into the repo.

>We are grateful to you for your opinion, but you haven't provided the reasonable claims, this change corrects the bug (proved by >the test), works in several appcontext(proved by the test), about what you objects?

Please see the other mail in which I provide a reason for my insistence of SentEvent not getting pushed to the event queue.
I derived my confidence from debugging the issue. I don’t think I'm wrong there.
As for the fix, mine is a simplistic one, which fixes the issue without much change. If you feel that, it is not sufficient, let me know what else you want to be changed.

PS: I did not see the other mail before I replied to this one.

Thanks,
Krishna

>>
>> When I said two app contexts, one is created by default, and I have 
>> created another one explicitly, which is why I said 2 app contexts.
>> Event one is posted on the default context, whereas the other two are 
>> posted on the newly created context. And I have also added two dummy 
>> events between two sequenced events just to make sure that, that case 
>> also works.
>>
>> Thanks,
>> Krishna
>>
>> -----Original Message-----
>> From: Semyon Sadetsky
>> Sent: Friday, March 16, 2018 12:01 AM
>> To: Krishna Addepalli <krishna.addepalli at oracle.com>; 
>> awt-dev at openjdk.java.net
>> Subject: Re: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>> sequenced events
>>
>> Please understand that you are modifying the mechanism that is 
>> responsible for synchronization between different application contexts.
>>
>> You must prove that you did not broke it with your change. But the 
>> provided test contains one context only.
>>
>> On 03/15/2018 10:30 AM, Krishna Addepalli wrote:
>>> Yes, When we create SequencedEvents, only FOCUS_LAST+1 ids are 
>>> pushed to the queue, but no event with FOCUS_LAST+2 are pushed. The
>>> order(creation) is maintained by having a static List.
>>> There is only one public constructor for SequencedEvents, and it 
>>> always creates with FOCUS_LAST + 1 as the id for all the events. So, 
>>> there is no event with FOCUS_LAST + 2 being pushed in the context of 
>>> a SequencedEvent.,
>>>
>>> Also, looking at the logic of the code, what we are saying is that 
>>> all the SequencedEvents should be processed before any other events 
>>> in the event queue. Thanks to Sergey for pointing this one out.
>>>
>>> My test case already contains two app contexts, and I have posted 
>>> events on both, creating a dependency between them. Let me know if 
>>> you want me to add more app contexts.
>>>
>>> Thanks,
>>> Krishna
>>>
>>> -----Original Message-----
>>> From: Semyon Sadetsky
>>> Sent: Thursday, March 15, 2018 10:48 PM
>>> To: Krishna Addepalli <krishna.addepalli at oracle.com>; 
>>> awt-dev at openjdk.java.net
>>> Subject: Re: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>>> sequenced events
>>>
>>> On 03/15/2018 10:11 AM, Krishna Addepalli wrote:
>>>
>>>> If no such event is posted to the queue, it will lead to hang right?
>>> Are you sure that the root cause is that there are no such event?
>>> I think the event is enqueued but its order is wrong.
>>>
>>> The test to the fix must contain several application contexts 
>>> because this mechanism provides synchronization between contexts.
>>>
>>> --Semyon
>>>> And also, the correct order of processing is not by the event 
>>>> number, but rather by the condition check to see if the current 
>>>> event is the first event in the separate list maintained for 
>>>> SequencedEvents.
>>>> Just repeating it for reference:
>>>> "edt.pumpEvents(ID, () -> !SequencedEvent.this.isFirstOrDisposed());"
>>>>
>>>> Thanks,
>>>> Krishna
>>>>
>>>> -----Original Message-----
>>>> From: Semyon Sadetsky
>>>> Sent: Thursday, March 15, 2018 10:36 PM
>>>> To: Krishna Addepalli <krishna.addepalli at oracle.com>; 
>>>> awt-dev at openjdk.java.net
>>>> Subject: Re: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>>>> sequenced events
>>>>
>>>> On 03/15/2018 09:59 AM, Krishna Addepalli wrote:
>>>>
>>>>> Hi Semyon,
>>>>>
>>>>> SequencedEvent is created with FOCUS_LAST + 1 as its id, whereas 
>>>>> when it is dispatching events, it is looking for FOCUS_LAST + 2, 
>>>>> which is causing the hang.
>>>> I think it correctly waits for FOCUS_LAST + 2 to guaranty the right 
>>>> order of processing in which the sequenced event is first processed 
>>>> on another EDT.
>>>> --Semyon
>>>>> I have modified it to look for only FOCUS_LAST + 1 events, which 
>>>>> has fixed the problem.
>>>>>
>>>>> Thanks,
>>>>> Krishna
>>>>>
>>>>> -----Original Message-----
>>>>> From: Semyon Sadetsky
>>>>> Sent: Thursday, March 15, 2018 9:14 PM
>>>>> To: Krishna Addepalli <krishna.addepalli at oracle.com>; 
>>>>> awt-dev at openjdk.java.net
>>>>> Subject: Re: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>>>>> sequenced events
>>>>>
>>>>> Hi Krishna,
>>>>>
>>>>> You have replaced FOCUS_LAST+2 with the FOCUS_LAST+1 which is 
>>>>> absolutely different event.
>>>>>
>>>>> They can be used interchangeably?
>>>>>
>>>>> --Semyon
>>>>>
>>>>>
>>>>> On 03/14/2018 07:53 AM, Krishna Addepalli wrote:
>>>>>> Hi Sergey,
>>>>>>
>>>>>> As per our discussion, I have modified the fix to process only 
>>>>>> SequencedEvents and ignore others. I have also modified the test 
>>>>>> case to include some dummy events between two SequencedEvents, 
>>>>>> and it works.
>>>>>> Here is the new webrev:
>>>>>> http://cr.openjdk.java.net/~kaddepalli/8152974/webrev01/
>>>>>>
>>>>>> However, could you point me to a doc/spec which says that all the 
>>>>>> SequencedEvents have to be processed together, even if other 
>>>>>> events in the queue have arrived before?
>>>>>>
>>>>>> Thanks,
>>>>>> Krishna
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Krishna Addepalli
>>>>>> Sent: Saturday, February 17, 2018 7:57 AM
>>>>>> To: Sergey Bylokhov <sergey.bylokhov at oracle.com>; 
>>>>>> awt-dev at openjdk.java.net; Semyon Sadetsky 
>>>>>> <semyon.sadetsky at oracle.com>
>>>>>> Subject: RE: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>>>>>> sequenced events
>>>>>>
>>>>>> Hi Sergey,
>>>>>>
>>>>>> The event is present, but with the id 
>>>>>> "java.awt.event.FocusEvent.FOCUS_LAST+1", whereas when it is 
>>>>>> pumping the events, it is looking for 
>>>>>> "java.awt.event.FocusEvent.FOCUS_LAST+2", which is not in the queue.
>>>>>>
>>>>>> Thanks,
>>>>>> Krishna
>>>>>>
>>>>>> -----Original Message-----
>>>>>> From: Sergey Bylokhov
>>>>>> Sent: Saturday, February 17, 2018 1:49 AM
>>>>>> To: Krishna Addepalli <krishna.addepalli at oracle.com>; 
>>>>>> awt-dev at openjdk.java.net; Semyon Sadetsky 
>>>>>> <semyon.sadetsky at oracle.com>
>>>>>> Subject: Re: <AWT Dev> [11][JDK-8152974] AWT hang occurs when 
>>>>>> sequenced events
>>>>>>
>>>>>> Hi, Krishna.
>>>>>> On 16/02/2018 00:42, Krishna Addepalli wrote:
>>>>>>> The SentEvent.ID value is
>>>>>>> "java.awt.event.FocusEvent.FOCUS_LAST+2", and when in the 
>>>>>>> function pumpOneEventForFilters, it tries to call 
>>>>>>> EventQueue.getNextEvent(id), it looks for SentEvent.ID, which is 
>>>>>>> not present, and then the queue blocks in the hope that someone 
>>>>>>> will post that event. This is what is leading to the hang.
>>>>>> But both events are posted by the test, why the second event is 
>>>>>> not present in the queue?
>>>>>>
>>>>>>
> 

--
Best regards, Sergey.