jmx-dev JDK-7120365 DiffHBTest.java fails due to ConcurrentModificationException

[shanliang]

Yes should use a cop[y, it is a mistake to use a unmodifiable view.

Here is the new webrev:
    http://cr.openjdk.java.net/~sjiang/JDK-7120365/webrev.02/

I have added a new test to reproduce the bug in an almost sure way.

Thanks,

Shanliang

Alan Bateman wrote:
> On 24/12/2012 14:08, shanliang wrote:
>> webrev: http://cr.openjdk.java.net/~sjiang/JDK-7120365/webrev.00/
>>
>> The test is correct, it was implemented to verify the fix for bug 
>> 4911721, but in addition it detects luckily another problem within 
>> the method ServerNotifForwarder.snoopOnUnregister
>>
>> The problem was that during a "for" cycle, the set list was modified 
>> by anther thread, the solution is to use a unmodifiable set.
>>
>> This fix is important, it not only re-enables a test, but also fixes 
>> a concurrent modification bug in the jmx notification.
>>
>> Shanliang
> Are you sure this is right? I don't know this code but from a brief 
> glance then it appears to me that all access to listenerMap requires 
> first synchronizes on it and maybe you need to do this and then take a 
> copy (not a unmodifiable view) of the delegate set before you iterate 
> over it. Apologies if you looked at this in detail, it's just not 
> clear to me how using an unmodifiable view fixes the problem if the 
> issue is actually that other threads are modifying the set.
>
> -Alan