jmx-dev [PATCH] JDK-6809322: Missing notifications from javax.management.timer.Timer

[David Holmes]

Hi Jaroslav,


On 11/10/2012 6:07 PM, Jaroslav Bachorik wrote:
> Dmitry has put the webrev on the public CR -
> http://cr.openjdk.java.net/~dsamersoff/sponsorship/jbachorik/JDK-6809322-v2/
>
> Thanks!
>
> -JB-
>
> On 10/10/2012 04:17 PM, Jaroslav Bachorik wrote:
>> I am looking for a review and a sponsor.
>>
>> The issue is about some javax.management.timer.Timer notifications not
>> being received by the listeners if the notifications are generated rapidly.
>>
>> The problem is caused by ConcurrentModificationException being thrown -
>> the exception itself is ignored but the dispatcher logic is skipped.
>> Therefore the currently processed notification gets lost.

Can you point out where exactly in the code the exception is thrown and 
caught. I'd like to understand the problem better.

>>
>> The CME is thrown due to the Timer.timerTable being iterated over while
>> other threads try to remove some of its elements. Fix consists of
>> replacing the Hashtable used for Timer.timerTable by ConcurrentHashMap
>> which handles such situations with grace.

Be aware that it may also give surprising results as removal is no 
longer synchronized at all with processing. So it could now appear that 
a notification is processed after a listener has been removed.

David
-----

>> The patch webrev is available @
>> https://jbs.oracle.com/bugs/browse/JDK-6809322
>>
>> Thanks,
>>
>> -JB-
>>
>