RFR: 8234742: Improve handshake logging

[Per Liden]

Hi,

I just realized that my comment on "8234796: Refactor Handshake::execute 
to take a HandshakeOperation" is probably more relevant for this change, 
so cut-n-pasting it here:


I kind of think HandshakeOperation is exposing a too wide API here. I'm 
thinking the following things doesn't quite belong in there, but is more 
Handshake internal stuff.

   void do_handshake(JavaThread* thread);
   bool thread_has_completed() { return _done.trywait(); }
   bool executed() const { return _executed; }

#ifdef ASSERT
   void check_state() {
     assert(!_done.trywait(), "Must be zero");
   }
#endif

How about you just expose a closure that inherits from ThreadClosure, 
but also takes a name? Like this:

class HandshakeClosure : public ThreadClosure {
private:
   const char* const _name;

public:
   HandshakeClosure(const char* name) :
       _name(name) {}

   const char* name() const {
     return _name;
   }

   virtual void do_thread(Thread* thread) = 0;
};

That way we expose a narrower API, and it also helps avoid the need for 
HandshakeOperation -> ThreadClosure wrappers. The other stuff can stay 
internal in a wrapping HandshakeThreadOperation like it did before.

What do you think?

/Per


On 11/26/19 2:06 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/
> 
> 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