On 2020/04/09 15:44, serguei.spit...@oracle.com wrote:
On 4/8/20 23:36, Yasumasa Suenaga wrote:
Thanks David and Serguei!
I created 3 subtasks under JDK-8201641, of course I will send review request in
each them.
- GetOneCurrentContendedMonitor => GetCurrentContendedMonitor
`GetCurrentContendedMonitor` is JVMTI function name, and also it exists as
public member of JvmtiEnv class.
So I want to different name for HandshakeClosure - for example,
GetCurrentContendedMonitorClosure.
Do you have any idea for it?
It is better to follow the same pattern as we already have in other places
(until a decision is made about a different rule).
So, the GetCurrentContendedMonitorClosure should work for now.
It is interesting if there will be any other suggestions though.
Currently, most of classes which extend HandshakeClosure have "Closure" as
suffix in below:
```
$ grep -nrw HandshakeClosure * | grep -w class
share/gc/shenandoah/shenandoahUnload.cpp:161:class
ShenandoahUnloadRendezvousClosure : public HandshakeClosure {
share/gc/z/zHeap.cpp:333:class ZRendezvousClosure : public HandshakeClosure {
share/gc/z/zMark.cpp:422:class ZMarkFlushAndFreeStacksClosure : public
HandshakeClosure {
share/prims/whitebox.cpp:2046: class TraceSelfClosure : public
HandshakeClosure {
share/runtime/biasedLocking.cpp:505:class RevokeOneBias : public
HandshakeClosure {
share/runtime/deoptimization.cpp:808:class DeoptimizeMarkedClosure : public
HandshakeClosure {
share/runtime/handshake.hpp:44:class HandshakeClosure : public ThreadClosure {
share/runtime/sweeper.cpp:200:class NMethodMarkingClosure : public
HandshakeClosure {
share/runtime/thread.cpp:528:class InstallAsyncExceptionClosure : public
HandshakeClosure {
share/runtime/vmThread.cpp:391:class HandshakeALotClosure : public
HandshakeClosure {
```
I think `GetCurrentContendedMonitorClosure` is not so bad :)
Thanks,
Yasumasa
Thanks,
Serguei
Yasumasa
On 2020/04/09 15:19, serguei.spit...@oracle.com wrote:
Hi Yasumasa,
I'm okay with using sub-tasks to do it incrementally.
This needs to be removed with your fix:
src/hotspot/share/runtime/vmOperations.hpp:
template(GetCurrentContendedMonitor) \
Also, I agree with comments from David below:
- GetOneCurrentContendedMonitor => GetCurrentContendedMonitor
- Thread::current() => calling_thread
I hope, you will update the copyright comments in jvmtiEnvBase.?pp.
Are you going to re-post this as an RFR with a correct sub-task number?
Thanks,
Serguei
On 4/8/20 22:52, David Holmes wrote:
Hi Yasumasa,
On 9/04/2020 3:08 pm, Yasumasa Suenaga wrote:
Hi,
JDK-8240918 has been pushed, so I made a patch for
GetCurrentContendedMonitor(). How about this?
http://cr.openjdk.java.net/~ysuenaga/jvmti-thread-local-handshake/2/
Generally looks okay. A couple of comments:
src/hotspot/share/prims/jvmtiEnv.cpp
Please update the comment just before the change:
// thread. All other usage needs to use a vm-safepoint-op for safety.
---
GetOneCurrentContendedMonitor
I don't think you need to add One into the name here - the current contended
monitor is inherently a singleton.
---
src/hotspot/share/prims/jvmtiEnvBase.cpp
655 Thread::current() == java_thread->active_handshaker() ||
The calling_thread parameter is now the current thread. So this can also be
changed:
679 Handle hobj(Thread::current(), obj);
An observation, it seems to me that calling_thread is not used when this is not
a VMOperation.
calling_thread is used for creating JNI reference:
```
*monitor_ptr = jni_reference(calling_thread, hobj);
```
If it is ok, I will make patches for other JVMTI functions.
However the patch might be bigger, so I want to separate as below. What do you
think?
(I think we can file them as subtask under JDK-8201641)
* Monitor operation
- VM_GetOwnedMonitorInfo
- VM_GetCurrentContendedMonitor
* Frame operation
- VM_UpdateForPopTopFrame
- VM_SetFramePop
* Thread operation
- VM_GetFrameCount
- VM_GetFrameLocation
- VM_GetThreadListStackTraces
- VM_GetCurrentLocation
- VM_EnterInterpOnlyMode
Creating subtasks with separate RFRs is fine by me. It may be good to slowly
introduce these changes so that we get some testing coverage to iron out any
initial bugs with the approach.
Thanks,
David
-----
Thanks,
Yasumasa
On 2020/04/01 21:29, Yasumasa Suenaga wrote:
Thanks David!
If JDK-8201641 is not assigned when JDK-8240918 is resolved, I will start to
work for JDK-8201641.
(It would be large patch...)
Cheers,
Yasumasa
On 2020/04/01 19:05, David Holmes wrote:
On 1/04/2020 11:02 am, Yasumasa Suenaga wrote:
Thanks Dan and Serguei!
I added a comment for this to JDK-8201641.
David, can you share Bug ID for thread-to-thread handshake?
I want to record it to JDK-8201641 as a blocker.
https://bugs.openjdk.java.net/browse/JDK-8240918
I heard the RFR could be as soon as tomorrow :)
Cheers,
David
Yasumasa
On 2020/04/01 1:59, serguei.spit...@oracle.com wrote:
Hi Yasumasa,
Yes, this works needs to be done.
I'll take look at you webrev.
Thanks,
Serguei
On 3/31/20 07:41, Daniel D. Daugherty wrote:
Add Robbin to this thread...
This reminded of the following RFE that Robbin filed:
JDK-8201641 JVMTI: GetThreadListStackTraces should use Thread-Local
Handshakes
https://bugs.openjdk.java.net/browse/JDK-8201641
We could update 8201641 to include everything that Yasumasa-san is requesting.
Would be a good place to track it...
Dan
On 3/31/20 7:40 AM, Yasumasa Suenaga wrote:
Hi David,
On 2020/03/31 19:16, David Holmes wrote:
Hi Yasumasa,
On 31/03/2020 8:06 pm, Yasumasa Suenaga wrote:
Hi all,
Many JVMTI functions uses VM Operation to get information. However some of them
need to stop only one thread - they don't need to stop all threads.
So I think we can use Thread Local Handshake as this webrev. It is example for
GetOneCurrentContendedMonitor().
True, but at the moment handshakes involve the VMThread. There is work being
done to support direct thread-to-thread handshakes and once that is done this
kind of conversion should be more easily done. It might be worth waiting for
that.
Thanks, I will be back to this topic when thread-to-thread handshake is done.
I wondered at first why VMThread involves handshake. Its improvement is welcome
for me ;)
Cheers,
Yasumasa
http://cr.openjdk.java.net/~ysuenaga/jvmti-thread-local-handshake/
An observation, it seems to me that calling_thread is not used when this is not
a VMOperation.
Cheers,
David
Also I think we can replace following VM Operations to Thread Local Handshake:
class VM_GetCurrentLocation
class VM_EnterInterpOnlyMode
class VM_UpdateForPopTopFrame
class VM_SetFramePop
class VM_GetOwnedMonitorInfo
class VM_GetCurrentContendedMonitor
class VM_GetFrameCount
class VM_GetFrameLocation
What do you think?
It it is acceptable, I will file it to JBS and send review request.
Thanks,
Yasumasa
