RFR(S): 8200374: Add ThreadsSMRSupport::verify_hazard_pointer_scanned() to verify threads_do()

[Daniel D. Daugherty]

Greetings,

Sorry for the delay in getting back to this thread... I'm traveling so
things take longer than usual...

I would love to get a final re-review from David H, Erik O, and Robbin.

Very little has changed on the OpenJDK side of this fix. I added an
assert() that caught a sampler thread life-cycle issue and I'm using
OrderAccess::release_store() for proper matching with load_acquire().

Here's the incremental webrev:

http://cr.openjdk.java.net/~dcubed/8200374-webrev/3_for_jdk_hs_open.inc/

And here's the full webrev:

http://cr.openjdk.java.net/~dcubed/8200374-webrev/3_for_jdk_hs_open.full/

I've done three  Mach5 builds-tier1, jdk-tier[1-3], and hs-tier[1-3] runs
and there are no test failures related to these changes. I just kicked of
one more Mach5 builds-tier1, jdk-tier[1-3], and hs-tier[1-3] run on the
latest rebased bits...

My Solaris-X64 server is finishing the third round of Thread-SMR stress
testing on this version. There are no test failures related to these
changes (so far)...

Thanks, in advance, for any comments, suggestions, or feedback.

Dan

Dan


On 4/3/18 5:25 PM, Daniel D. Daugherty wrote:
> Greetings,
>
> This fix has been revised due to feedback from David H. and Erik O.
>
> Here's the incremental webrev:
>
> http://cr.openjdk.java.net/~dcubed/8200374-webrev/2_for_jdk_hs_open.inc/
>
> And here's the full webrev:
>
> http://cr.openjdk.java.net/~dcubed/8200374-webrev/2_for_jdk_hs_open.full/
>
> Summary of the changes relative to 'cr1':
>
> - Rename TracingExport::get_sampler_thread() to sampler_thread_acquire()
>   and TracingExport::set_sampler_thread() to 
> set_sampler_thread_with_lock().
> - set_sampler_thread_with_lock() uses Threads_lock to avoid conflicts 
> with
>   Thread-SMR scans.
>
> The Mach5 builds-tier1, jdk-tier[1-3], and hs-tier[1-3] run has finished
> and there are no test failures related to these changes.
>
> My Solaris-X64 server is finishing the third round of Thread-SMR stress
> testing on the 'cr1' version. I'll start a round of stress testing for
> this version ('cr2') as soon as I can.
>
> Thanks, in advance, for any comments, suggestions, or feedback.
>
> Dan
>
> On 4/2/18 11:11 AM, Daniel D. Daugherty wrote:
>> Greetings,
>>
>> This fix has been revised due to additional testing and due to
>> feedback from David H.
>>
>> Here's the incremental webrev:
>>
>> http://cr.openjdk.java.net/~dcubed/8200374-webrev/1_for_jdk_hs_open.inc/
>>
>> And here's the full webrev:
>>
>> http://cr.openjdk.java.net/~dcubed/8200374-webrev/1_for_jdk_hs_open.full/ 
>>
>>
>> My usual Thread-SMR stress testing on my Solaris-X64 is still running;
>> so far there has been only one unrelated intermittent test failure. The
>> Mach5 builds-tier1, jdk-tier[1-3], and hs-tier[1-3] run is still in
>> process...
>>
>> Thanks, in advance, for any comments, suggestions, or feedback.
>>
>> Dan
>>
>>
>> On 3/28/18 9:52 PM, Daniel D. Daugherty wrote:
>>> Greetings,
>>>
>>> I have a (mostly) small enhancement for Thread-SMR:
>>>
>>> JDK-8200374 Add ThreadsSMRSupport::verify_hazard_pointer_scanned() 
>>> to verify threads_do()
>>> https://bugs.openjdk.java.net/browse/JDK-8200374
>>>
>>> Here's the webrev URL:
>>>
>>> http://cr.openjdk.java.net/~dcubed/8200374-webrev/0_for_jdk_hs_open/
>>>
>>> This is Erik O's improvement on the assertion added by the following
>>> bug fix (with some minor tweaking done by me):
>>>
>>> JDK-8199813 SIGSEGV in ThreadsList::includes()
>>> https://bugs.openjdk.java.net/browse/JDK-8199813
>>>
>>> Summary of the changes:
>>>
>>> - Replace the assertion that I added in JDK-8199813 with a closure
>>>   based function that verifies the threads_do() contract depended
>>>   on by Thread-SMR.
>>> - Add ThreadsSMRSupport::verify_hazard_pointer_scanned() to verify
>>>   that the calling thread's hazard pointer is scanned by threads_do().
>>>   The new function is called from both ThreadsSMRSupport::acquire_*()
>>>   functions.
>>> - Refactor the non-JavaThread part of Threads::threads_do() into
>>>   Threads::non_java_threads_do() so that the non-JavaThread part
>>>   can also be called by other threads_do() functions. Yes, the
>>>   Threads::threads_do() contract is still to scan every thread in
>>>   the system.
>>> - Add hooks for a "tracing sampler thread" to be optionally scanned
>>>   by Threads::non_java_threads_do().
>>>
>>> This fix has gone thru a couple of Mach5 builds-tier1, jdk-tier[1-3],
>>> and hs-tier[1-3] runs. I've also started my usual 24+ hour Thread-SMR
>>> stress testing run on my Solaris-X64 server.
>>>
>>> Just to be extra sure, I backed out the fix from JDK-8199813 to
>>> JavaThread::verify_not_published() (which started this round of
>>> Thread-SMR fixes) and we catch the issue in the new function
>>> ThreadsSMRSupport::verify_hazard_pointer_scanned().
>>>
>>> Thanks, in advance, for any comments, suggestions, or feedback.
>>>
>>> Dan
>>>
>>>
>>
>>
>
>