RFR: 8269934: RunThese24H.java failed with EXCEPTION_ACCESS_VIOLATION in java_lang_Thread::get_thread_status

[David Holmes]

On Tue, 3 Aug 2021 06:12:35 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> wrote:

>> If a thread is attaching via JNI and has not yet created its Thread object it can be caught in a ThreadSnapshot during a thread dump (VM_DumpThreads) of all threads**, and the threadObj() will be NULL, so we can't pass it to get_thread_status().
>> 
>> ** JMM dumpThreads API
>> 
>> The initial fix simply checks for a NULL threadObj() and reports thread status NEW in that case.
>> 
>> Alternatively we could filter the attaching thread out completely in VM_DumpThreads::doit by expanding:
>> 
>>       if (jt->is_exiting() ||
>>           jt->is_hidden_from_external_view())  {
>>         // skip terminating threads and hidden threads
>>         continue;
>>       }
>> 
>> to also check jt->is_attaching_via_jni().
>> 
>> Note that higher-level code already filters out ThreadSnapshots with NULL threadObj() anyway so we could go either way.
>> 
>> Testing: manual hacks - see bug report.
>>   - tier 1-3 sanity testing
>> 
>> Thanks,
>> David
>
> Hi David,
> The fix looks fine to me.
> Thanks,
> Serguei

Thanks for the review @sspitsyn !

-------------

PR: https://git.openjdk.java.net/jdk/pull/4921