RFR: 8273608: Deadlock when jcmd of OnError attaches to itself [v4]

[Liu, Xin]

hi, David,

Thanks for pointing it out. Understood.

-XX:MaxMetaspaceSize is neat, but it's still subject to initialization
process. I tried different approaches to throw OOME in the test, so far,
I think throwing from NIO is the most reliable one.

thanks,
--lx



On 10/5/21 6:47 PM, David Holmes wrote:
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> 
> 
> On 6/10/2021 11:39 am, Xin Liu wrote:
>> On Tue, 5 Oct 2021 18:27:45 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:
>>
>>>> Xin Liu has updated the pull request incrementally with one additional commit since the last revision:
>>>>
>>>>    Cleanup: remove a statment of debugging.
>>>
>>> test/hotspot/jtreg/runtime/ErrorHandling/TestOutOfMemoryErrorFromNIO.java line 25:
>>>
>>>> 23:
>>>> 24: /*
>>>> 25:  * @test TestOutOfMemoryErrorFromNIO
>>>
>>> I would rename the test. The point is not to test OOM from NIO, but to test XX:OnError with jcmd which attaches to the parent.
>>>
>>> You could do the same with any OOM, right? E.g. just start the VM with a very small MaxMetaspaceSize. You would not even need a main function for that, since the VM would not come up but throw a OOM right away,
>>>
>>> Proposal (but feel free to come up with something better): "TestOnErrorWithSelfAttachingJCmd"
>>
>> I found HotSpot is very subtle when it comes to `MaxMetaspaceSize` and `-XX:AbortVMOnException=java.lang.OutOfMemoryError`
>>
>> On my host, the watershed is 3M. If I give it 2M, it will ignore `AbortVMOnException`.
>>
>>
>> java -XX:MaxMetaspaceSize=2M -XX:AbortVMOnException=java.lang.OutOfMemoryError
>> Error occurred during initialization of VM
>> OutOfMemoryError: Metaspace
>>
>>
>> Flip code blocks here can solve this problem. is it intentional?
> 
> Yes it is intentional. If init has not completed you probably can't
> throw exceptions yet.
> 
> David
> -----
> 
>>
>> diff --git a/src/hotspot/share/memory/metaspace.cpp b/src/hotspot/share/memory/metaspace.cpp
>> index 74b5d1a0b30..efe430f7d3c 100644
>> --- a/src/hotspot/share/memory/metaspace.cpp
>> +++ b/src/hotspot/share/memory/metaspace.cpp
>> @@ -974,15 +974,16 @@ void Metaspace::report_metadata_oome(ClassLoaderData* loader_data, size_t word_s
>>           space_string);
>>     }
>>
>> -  if (!is_init_completed()) {
>> -    vm_exit_during_initialization("OutOfMemoryError", space_string);
>> -  }
>> -
>>     if (out_of_compressed_class_space) {
>>       THROW_OOP(Universe::out_of_memory_error_class_metaspace());
>>     } else {
>>       THROW_OOP(Universe::out_of_memory_error_metaspace());
>>     }
>> +
>> +  if (!is_init_completed()) {
>> +    vm_exit_during_initialization("OutOfMemoryError", space_string);
>> +  }
>> +
>>   }
>>
>> -------------
>>
>> PR: https://git.openjdk.java.net/jdk/pull/5590
>>