RFR(XS): 8205195 NestedThreadsListHandleInErrorHandlingTest fails because hs_err doesn't contain _nested_thread_list_max

[Daniel D. Daugherty]

David,

Thanks for your eagle eyes! More below...


On 6/25/18 9:27 AM, Daniel D. Daugherty wrote:
> On 6/25/18 1:57 AM, David Holmes wrote:
>> Hi Dan,
>>
>> On 21/06/2018 10:18 AM, Daniel D. Daugherty wrote:
>>> Greetings,
>>>
>>> I have a fix for a recent (very rare) Thread-SMR related test failure.
>>>
>>> Since the fix is related to the ErrorHandling tests and affects 
>>> hs_err_pid
>>> file generation, this code review is being sent to both the Runtime and
>>> the Serviceability teams. Please make sure you reply-all to any 
>>> responses
>>> so we have complete review threads on both aliases.
>>>
>>> Bug URL: https://bugs.openjdk.java.net/browse/JDK-8205195
>>>
>>> Webrev URL: 
>>> http://cr.openjdk.java.net/~dcubed/8205195-webrev/0-for-jdk-jdk/
>>>
>>> The bug itself contains analysis about the root cause of the bug and
>>> the comment updates to the code describes the no win scenario that the
>>> hs_err_pid file generation code is in. Of course, I also have a comment
>>> where I was able to harden the ErrorHandling tests. I did manage to
>>> resist the urge to mention the "Kobiyashi Maru" [1] in the new 
>>> comments.
>>>
>>> Testing: Mach5 
>>> builds-tier1,jdk-tier1,jdk-tier2,hs-tier1,hs-tier2,hs-tier3
>>>           on the usual Oracle platforms.
>>>
>>> Thanks, in advance, for any comments, questions or suggestions.
>>
>> I don't quite follow the fix.
>
> I think this comment explains what the fix is _trying_ to do:
>
> 1702   // We grab Threads_lock to keep ThreadsSMRSupport::print_info_on()
> 1703   // from racing with Threads::add() or Threads::remove() as we
> 1704   // generate the hs_err_pid file. This makes our ErrorHandling 
> tests
> 1705   // more stable.
>
>
>> Won't you self-deadlock on acquiring the Threads_lock in the 
>> secondary error handler test, due to the recursive call to 
>> controlled_crash ?
>
> I missed that possibility, but now I'm puzzled why my testing didn't
> reveal this situation. We have a test for secondary error handling
> and it should have self-deadlocked (and failed). I'll investigate.

The ErrorHandling tests don't run with 'release' bits so no self-deadlock.
The 'fastdebug' and 'slowdebug' versions will fail an assertion that gets
hidden by the fact that it is a secondary failure mode.

I've filed the following bug:

JDK-8205648 fix for 8205195 breaks secondary error handling
https://bugs.openjdk.java.net/browse/JDK-8205648

Dan


>
> Dan
>
>
>>
>> David
>>
>>> Dan
>>>
>>> [1] https://www.urbandictionary.com/define.php?term=Kobayashi%20Maru
>>>
>
>