RFR: 8234742: Improve handshake logging

Thu Nov 28 13:21:29 UTC 2019

Thanks David!

/Robbin

On 2019-11-28 06:31, David Holmes wrote:
> Hi Robbin,
> 
> Updates all seem fine.
> 
> Thanks,
> David
> 
> On 28/11/2019 1:51 am, Robbin Ehn wrote:
>> Hi David, thanks for having a look!
>>
>> On 11/27/19 4:25 AM, David Holmes wrote:
>>> Hi Robbin,
>>>
>>> On 26/11/2019 11:06 pm, Robbin Ehn wrote:
>>>> Hi,
>>>>
>>>> Here is the logging part separately:
>>>> http://cr.openjdk.java.net/~rehn/8234742/v2/full/webrev/index.html
>>>>
>>>> It contains one additional change from the first version:
>>>>       if (number_of_threads_issued < 1) {
>>>> -      log_debug(handshake)("No threads to handshake.");
>>>> +      log_handshake_info(start_time_ns, _op->name(), 0, 0, " (no threads)");
>>>>         return;
>>>>       }
>>>>
>>>> Passes t1-3.
>>>>
>>>> So this goes on top of 8234796:
>>>> http://cr.openjdk.java.net/~rehn/8234796/full/webrev/
>>>
>>> src/hotspot/share/runtime/handshake.hpp
>>>
>>> I was surprised that "process_by_vmthread" doesn't really mean that. Perhaps 
>>> rename to try_process_by_vmThread?
>>
>> I did, but also renamed:
>> bool handshake_process_by_vmthread() in thread.hpp
>>
>>>
>>> ---
>>>
>>> src/hotspot/share/runtime/handshake.cpp
>>>
>>> 91     log_info(handshake)("Handshake \"%s\", Targeted threads: %d, Executed 
>>> by targeted threads: %d, Total completion time: " JLONG_FORMAT " ns%s",
>>>
>>> Probably better to end with " ns, %s" so you don't have to remember to start 
>>> the 'extra' string with a space each time.
>>
>> Fixed, but I didn't like the ending "," when the string was empty, so I did a
>> different fix!
>>
>>>
>>> 168     log_trace(handshake)("Threads signaled, begin processing blocked 
>>> threads by VMThtread")
>>>
>>> Existing typo: VMThtread
>>
>> Fixed!
>>
>>>
>>> Otherwise seems okay.
>>>
>>
>> v3 which is also rebased on latest 8234796:
>> Inc:
>> http://cr.openjdk.java.net/~rehn/8234742/v3/inc/webrev/index.html
>> Full:
>> http://cr.openjdk.java.net/~rehn/8234742/v3/full/webrev/index.html
>>
>> t1-3
>>
>> Thanks, Robbin
>>
>>> Thanks,
>>> David
>>> -----
>>>
>>>> Thanks, Robbin
>>>>
>>>> On 11/25/19 5:33 PM, Robbin Ehn wrote:
>>>>> Hi all, please review.
>>>>>
>>>>> There is little useful information in the handshaking logs.
>>>>> This changes the handshakes logs similar to safepoint logs, so the basic 
>>>>> need of
>>>>> what handshake operation and how long it took easily can be tracked.
>>>>> Also the per thread log is a bit enhanced.
>>>>>
>>>>> The refactoring using HandshakeOperation instead of a ThreadClosure is not
>>>>> merely for this change. Other changes in the pipeline also require a more
>>>>> complex HandshakeOperation.
>>>>>
>>>>> Issue:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8234742
>>>>> Changeset:
>>>>> http://cr.openjdk.java.net/~rehn/8234742/full/webrev/
>>>>>
>>>>> Passes t1-3.
>>>>>
>>>>> Thanks, Robbin
>>>>>
>>>>> Examples:
>>>>> -Xlog:handshake,safepoint
>>>>>
>>>>> [7.148s][info][safepoint] Safepoint "ZMarkStart", Time since last: 
>>>>> 381873579 ns, Reaching safepoint: 451132 ns, At safepoint: 491202 ns, 
>>>>> Total: 942334 ns
>>>>> [7.151s][info][handshake] Handshake "ZMarkFlushAndFreeStacks", Targeted 
>>>>> threads: 25, Executed by targeted threads: 8, Total completion time: 46884 ns
>>>>> [7.151s][info][handshake] Handshake "ZMarkFlushAndFreeStacks", Targeted 
>>>>> threads: 25, Executed by targeted threads: 10, Total completion time: 94547 ns
>>>>> [7.152s][info][handshake] Handshake "ZMarkFlushAndFreeStacks", Targeted 
>>>>> threads: 25, Executed by targeted threads: 10, Total completion time: 33545 ns
>>>>> [7.154s][info][safepoint] Safepoint "ZMarkEnd", Time since last: 4697901 
>>>>> ns, Reaching safepoint: 218800 ns, At safepoint: 1462059 ns, Total: 1680859 ns
>>>>> [7.156s][info][handshake] Handshake "ZRendezvous", Targeted threads: 25, 
>>>>> Executed by targeted threads: 10, Total completion time: 37291 ns
>>>>> [7.157s][info][safepoint] Safepoint "ZVerify", Time since last: 2201206 ns, 
>>>>> Reaching safepoint: 295463 ns, At safepoint: 928077 ns, Total: 1223540 ns
>>>>> [7.161s][info][safepoint] Safepoint "ZRelocateStart", Time since last: 
>>>>> 3161645 ns, Reaching safepoint: 206278 ns, At safepoint: 357284 ns, Total: 
>>>>> 563562 ns
>>>>> [8.162s][info][safepoint] Safepoint "Cleanup", Time since last: 1000123769 
>>>>> ns, Reaching safepoint: 526489 ns, At safepoint: 23345 ns, Total: 549834 ns
>>>>> [8.182s][info][handshake] Handshake "RevokeOneBias", Targeted threads: 1, 
>>>>> Executed by targeted threads: 0, Total completion time: 41322 ns
>>>>>
>>>>> -Xlog:handshake*=trace
>>>>>
>>>>> [1.259s][trace][handshake ] Threads signaled, begin processing blocked 
>>>>> threads by VMThtread
>>>>> [1.259s][trace][handshake ] Processing handshake by VMThtread
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f2594022800, is_vm_thread: true, completed in 487 ns
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f259459e000, is_vm_thread: false, completed in 1233 ns
>>>>> [1.259s][trace][handshake ] Processing handshake by VMThtread
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f25945a0000, is_vm_thread: false, completed in 669 ns
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f259428a800, is_vm_thread: true, completed in 462 ns
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f25945b3800, is_vm_thread: false, completed in 574 ns
>>>>> ...
>>>>> [1.259s][trace][handshake ] Processing handshake by VMThtread
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f25945b6000, is_vm_thread: true, completed in 100 ns
>>>>> [1.259s][trace][handshake ] Processing handshake by VMThtread
>>>>> [1.259s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f25945b7800, is_vm_thread: true, completed in 103 ns
>>>>> [1.260s][info ][handshake ] Handshake "ZRendezvous", Targeted threads: 28, 
>>>>> Executed by targeted threads: 4, Total completion time: 629534 ns
>>>>> [1.260s][debug][handshake,task ] Operation: ZRendezvous for thread 
>>>>> 0x00007f25945a3800, is_vm_thread: false, completed in 608 ns