RFR: 8234742: Improve handshake logging

[Robbin Ehn]

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