Patch review request - Test bug 7123972 test/java/lang/annotation/loaderLeak/Main.java fails intermittently

[Stuart Marks]

Webrev posted here:

http://cr.openjdk.java.net/~smarks/yiming.wang/7123972/webrev.2/

The changes look good. If there's no further discussion, I'll push them in a 
couple days.

s'marks

On 7/3/12 3:37 AM, Eric Wang wrote:
> Hi Stuart,
>
> I have made updates which is same as 6948101, please help to review, Thanks a lot!
>
> Regards,
> Eric
> On 2012/6/30 6:01, Stuart Marks wrote:
>> I've posted the updated webrev here:
>>
>> http://cr.openjdk.java.net/~smarks/yiming.wang/7123972/webrev.1/
>>
>> This code is pretty much the same as 6948101 and the same comments I had on
>> that bug apply here as well, so please make similar updates to this one.
>>
>> Thanks.
>>
>> s'marks
>>
>> On 6/29/12 1:36 AM, Eric Wang wrote:
>>> Hi Stuart & David，
>>>
>>> Attachment is the new changes to make code simply by following David
>>> suggestion, Can you help please review again, Thanks a lot!
>>>
>>> Regards,
>>> Eric
>>> On 2012/6/28 12:40, Stuart Marks wrote:
>>>> I've posted the webrev here:
>>>>
>>>> http://cr.openjdk.java.net/~smarks/yiming.wang/7123972/webrev.0/
>>>>
>>>> I've looked at the changes and they seem fine.
>>>>
>>>> It's interesting that the run times take 30-60 sec in your experience. I've
>>>> run them on my system (Linux in a virtual machine) and they usually run in
>>>> 10-20 sec. In any case, as you say, if the test times out it indicates there
>>>> really was a failure.
>>>>
>>>> I'll give people a chance to look at the webrev and if there aren't any more
>>>> comments in another day or so I'll push in the changeset.
>>>>
>>>> Thanks for developing this!
>>>>
>>>> s'marks
>>>>
>>>> On 6/26/12 11:50 PM, Eric Wang wrote:
>>>>> Hi David,
>>>>>
>>>>> Thank you! I run the test several times on 3 platforms (windows, solaris and
>>>>> linux), the average execution time is 30secs to 60secs. if the test hang 2
>>>>> minutes, there should be something wrong.
>>>>>
>>>>> Hi Marks,
>>>>>
>>>>> I don't have the author role, Can you please help to review and post the
>>>>> webrev
>>>>> 7123972.zip in attachment if it is OK, Thanks a lot!
>>>>>
>>>>> Regards,
>>>>> Eric
>>>>>
>>>>> On 2012/6/27 14:19, David Holmes wrote:
>>>>>> Eric,
>>>>>>
>>>>>> Ignore my comment about adding the timeouts. As Alan reminded me if the test
>>>>>> would hang then jtreg will time it out after two minutes anyway.
>>>>>>
>>>>>> So this is good to go as far as I am concerned.
>>>>>>
>>>>>> Thanks,
>>>>>> David
>>>>>>
>>>>>> On 27/06/2012 7:51 AM, David Holmes wrote:
>>>>>>> Thanks Eric.
>>>>>>>
>>>>>>> So to summarize:
>>>>>>>
>>>>>>> - we create a custom classloader, load a class through it and store a
>>>>>>> reference to that Class in a WeakReference
>>>>>>> - we then drop the reference to the loader
>>>>>>>
>>>>>>> At this point the only reference to the loader is from the Class loaded,
>>>>>>> which in turn is only weakly reachable.
>>>>>>>
>>>>>>> I must confess that I'm unclear why this test should be failing in its
>>>>>>> original form. The first gc() should remove the strong reference to the
>>>>>>> loader. That leaves a weak cycle: WeakRef -> Class -> Loader -> Class.
>>>>>>> The second gc() should detect the cycle and clear the WeakRef. I guess
>>>>>>> the problem is that depending on which gc is in use the actual gc()
>>>>>>> calls may not in fact induce every possible GC action.
>>>>>>>
>>>>>>> The fix seems reasonable in that regard - keep gc'ing and finalizing
>>>>>>> till we see the loader is gone, and so the WeakReference should be
>>>>>>> cleared. The original bug would cause a ref to the Class to remain (from
>>>>>>> the annotation) and hence the WeakRef would not be cleared. However, in
>>>>>>> that case the loader would also be strongly referenced and so never
>>>>>>> become finalizable. So if this test was now run against a JDK with the
>>>>>>> original bug, the test would hang. So I think we need to add a timeout
>>>>>>> in there as well.
>>>>>>>
>>>>>>> David
>>>>>>>
>>>>>>> On 25/06/2012 6:06 PM, Eric Wang wrote:
>>>>>>>> On 2012/6/21 20:16, David Holmes wrote:
>>>>>>>>> Hi Eric,
>>>>>>>>>
>>>>>>>>> On 21/06/2012 8:57 PM, Eric Wang wrote:
>>>>>>>>>> Hi David,
>>>>>>>>>>
>>>>>>>>>> Thanks for your review, I have updated the code by following your
>>>>>>>>>> suggestion. please see the attachment.
>>>>>>>>>> I'm not sure whether there's a better way to guarantee object finalized
>>>>>>>>>> by GC definitely within the given time. The proposed fix may work in
>>>>>>>>>> most cases but may still throw InterruptException if execution is
>>>>>>>>>> timeout (2 minutes of JTreg by default).
>>>>>>>>>
>>>>>>>>> There is no way to guarantee finalization in a specific timeframe, but
>>>>>>>>> if a simple test hasn't executed finalizers in 2 minutes then that in
>>>>>>>>> itself indicates a problem.
>>>>>>>>>
>>>>>>>>> Can you post a full webrev for this patch? I don't like seeing it out
>>>>>>>>> of context and am wondering exactly what we are trying to GC here.
>>>>>>>>>
>>>>>>>>> David
>>>>>>>>>
>>>>>>>>>> Regards,
>>>>>>>>>> Eric
>>>>>>>>>>
>>>>>>>>>> On 2012/6/21 14:32, David Holmes wrote:
>>>>>>>>>>> Hi Eric,
>>>>>>>>>>>
>>>>>>>>>>> On 21/06/2012 4:05 PM, Eric Wang wrote:
>>>>>>>>>>>> I come from Java SQE team who are interested in regression test bug
>>>>>>>>>>>> fix.
>>>>>>>>>>>> Here is the first simple fix for bug 7123972
>>>>>>>>>>>> <http://monaco.us.oracle.com/detail.jsf?cr=7123972>, Can you please
>>>>>>>>>>>> help
>>>>>>>>>>>> to review and comment? Attachment is the patch Thanks!
>>>>>>>>>>>>
>>>>>>>>>>>> This bug is caused by wrong assumption that the GC is started
>>>>>>>>>>>> immediately to recycle un-referenced objects after System.gc() called
>>>>>>>>>>>> one or two times.
>>>>>>>>>>>>
>>>>>>>>>>>> The proposed solution is to make sure the un-referenced object is
>>>>>>>>>>>> recycled by GC before checking if the reference is null.
>>>>>>>>>>>
>>>>>>>>>>> Your patch makes its own assumptions - specifically that finalization
>>>>>>>>>>> must eventually run. At a minimum you should add
>>>>>>>>>>> System.runFinalization() calls after the System.gc() inside the loop.
>>>>>>>>>>> Even that is no guarantee in a general sense, though it should work
>>>>>>>>>>> for hotspot.
>>>>>>>>>>>
>>>>>>>>>>> David
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>> Regards,
>>>>>>>>>>>> Eric
>>>>>>>>>>
>>>>>>>> Hi Alan & David,
>>>>>>>>
>>>>>>>> Thank you for your comments, sorry for reply this mail late as i was
>>>>>>>> just back from the dragon boat holiday.
>>>>>>>> I have updated the code again based on your suggestions: rename the flag
>>>>>>>> variable, increase the sleep time and remove it from problem list.
>>>>>>>> The attachment is the full webrev for this patch, Can you please review
>>>>>>>> again? Thanks a lot!
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Eric
>>>>>
>>>
>
>