The failure

Robbin Ehn robbin.ehn at oracle.com
Wed Oct 24 09:18:32 UTC 2018


Hi Serguei,

On 24/10/2018 11:00, serguei.spitsyn at oracle.com wrote:
> Hi Robbin and David,
> 
> There is no JvmtiEnv::SuspendThreadList call in the dumped stack traces.
> But there is an instance of the JvmtiEnv::SuspendThread which seems to be 
> supporting your theory:

Sorry, I did mean any place we take a ThreadsListHandle and call ::execute with 
that handle still alive. That was just first one I saw and used it as an example.
> void JavaThread::java_suspend() {

You are correct in this particular case it seems to be this one, but we must fix 
_all_ of them. That why I suggested adding the assert. And maybe an additional 
assert in Mutex on having a threadslist while locking the Threads_lock.

> I'll check with Leonid tomorrow if we can check if your patch below can fix this 
> deadlock.

It wouldn't fix the deadlock it would assert, so we still need to locate and fix 
all the places. Maybe it's just a couple.

/Robbin

> 
> Thanks,
> Serguei
> 
> 
> On 10/24/18 00:18, Robbin Ehn wrote:
>> Hi, truncate:
>>
>> On 24/10/2018 02:00, serguei.spitsyn at oracle.com wrote:
>>>>> One thing I noticed which Robbin should be able to expand upon is that 
>>>>> Thread 101 is terminating and has called ThreadsSMRSupport::smr_delete and 
>>>>> is blocked here:
>>>>>
>>>>>   // Wait for a release_stable_list() call before we check again. No
>>>>>   // safepoint check, no timeout, and not as suspend equivalent flag
>>>>>   // because this JavaThread is not on the Threads list.
>>>>>   ThreadsSMRSupport::delete_lock()->wait(Mutex::_no_safepoint_check_flag,
>>>>>                                          0, 
>>>>> !Mutex::_as_suspend_equivalent_flag);
>>>>>
>>>>> As the comment says this thread is no longer on the Threads_list, but the 
>>>>> VM_HandshakeAllThreads is not a safepoint operation and does not hold the 
>>>>> Threads_lock, so is it possible this thread was captured by the 
>>>>> JavaThreadIteratorWithHandle being used by VM_HandshakeAllThreads, before 
>>>>> it got removed? If so we'd be hung waiting it for it handshake as it's not 
>>>>> in a "safepoint-safe" or suspend-equivalent state.
>>
>> In short:
>> # VM Thread
>> VM Thread is in a loop, takes Threads_lock, takes a new snapshot of the 
>> Threads_list, scans the list and process handshakes on behalf of safe threads.
>> Releases snapshot and Threads_lock and checks if all handshakes are completed
>>
>> # An exiting thread
>> A thread exiting thread removes it self from _THE_ threads list, but must 
>> stick around if it is on any snapshots of alive. When it is no on any list it 
>> will cancel the handshake.
>>
>> Since VM thread during the handshake takes a new snapshot every iteration any 
>> exiting can proceed since it will not be a the new snapshot. Thus cancel the 
>> handshake and VM thread can exit the loop (if this was the last handshake).
>>
>> Constraint:
>> If any thread grabs a snapshot of threads list and later tries to take a lock 
>> which is 'used' by VM Thread or inside the handshake we can deadlock.
>>
>> Considering that looking at e.g. : JvmtiEnv::SuspendThreadList
>> Which calls VMThread::execute(&tsj); with a ThreadsListHandle alive, this 
>> could deadlock AFAICT. Since the thread will rest on VMOperationRequest_lock 
>> with a Threads list snapshot but VM thread cannot finishes handshake until 
>> that snapshot is released.
>>
>> I suggest first step is to add something like this patch below and fix the 
>> obvious ones first.
>>
>> Note, I have not verified that is the problem you are seeing, I'm saying that 
>> this seem to be real issue. And considering how the stack traces looks, it may 
>> be this.
>>
>> You want me going through this, just assign a bug if there is one?
>>
>> /Robbin
>>
>> diff -r 622fd3608374 src/hotspot/share/runtime/thread.hpp
>> --- a/src/hotspot/share/runtime/thread.hpp    Tue Oct 23 13:27:41 2018 +0200
>> +++ b/src/hotspot/share/runtime/thread.hpp    Wed Oct 24 09:13:17 2018 +0200
>> @@ -167,2 +167,6 @@
>>    }
>> + public:
>> +  bool have_threads_list();
>> + private:
>> +
>>    // This field is enabled via -XX:+EnableThreadSMRStatistics:
>> diff -r 622fd3608374 src/hotspot/share/runtime/thread.inline.hpp
>> --- a/src/hotspot/share/runtime/thread.inline.hpp    Tue Oct 23 13:27:41 2018 
>> +0200
>> +++ b/src/hotspot/share/runtime/thread.inline.hpp    Wed Oct 24 09:13:17 2018 
>> +0200
>> @@ -111,2 +111,6 @@
>>
>> +inline bool Thread::have_threads_list() {
>> +  return OrderAccess::load_acquire(&_threads_hazard_ptr) != NULL;
>> +}
>> +
>>  inline void Thread::set_threads_hazard_ptr(ThreadsList* new_list) {
>> diff -r 622fd3608374 src/hotspot/share/runtime/vmThread.cpp
>> --- a/src/hotspot/share/runtime/vmThread.cpp    Tue Oct 23 13:27:41 2018 +0200
>> +++ b/src/hotspot/share/runtime/vmThread.cpp    Wed Oct 24 09:13:17 2018 +0200
>> @@ -608,2 +608,3 @@
>>    if (!t->is_VM_thread()) {
>> +    assert(t->have_threads_list(), "Deadlock if we have exiting threads and 
>> if vm thread is running an VM op."); // fatal/guarantee
>>      SkipGCALot sgcalot(t);    // avoid re-entrant attempts to gc-a-lot
>>
>>
>>
>>
>>
>>>>>
>>>>> David
>>>>> -----
>>>>>
>>>>> On 24/10/2018 9:18 AM, serguei.spitsyn at oracle.com wrote:
>>>>>> Please, skip it - sorry for the noise.
>>>>>> It is hard to prove anything with current dump.
>>>>>>
>>>>>> Thanks,
>>>>>> Serguei
>>>>>>
>>>>>> On 10/23/18 9:09 AM, serguei.spitsyn at oracle.com wrote:
>>>>>>> Hi David and Robbin,
>>>>>>>
>>>>>>> I have an idea that needs to be checked.
>>>>>>> It can be almost the same deadlock scenario that I've already explained 
>>>>>>> but more sophisticated.
>>>>>>> I suspect a scenario with JvmtiThreadState_lock that the flag 
>>>>>>> Monitor::_safepoint_check_always does not help much.
>>>>>>> It can be verified by checking what monitors are used by the blocked 
>>>>>>> threads.
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Serguei
>>>>>>>
>>>>>>>
>>>>>>> On 10/23/18 07:38, Robbin Ehn wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> On 10/23/18 10:34 AM, David Holmes wrote:
>>>>>>>>> Hi Serguei,
>>>>>>>>>
>>>>>>>>> The VMThread is executing VM_HandshakeAllThreads which is not a 
>>>>>>>>> safepoint operation. There's no real way to tell from the stacks what 
>>>>>>>>> it's stuck on.
>>>>>>>>
>>>>>>>> I cannot find a thread that is not considered safepoint safe or 
>>>>>>>> is_ext_suspended (thread 146). So the handshake should go through. The 
>>>>>>>> handshake will log a warning after a while, is there such warning from 
>>>>>>>> the handshake operation?
>>>>>>>>
>>>>>>>> There are several threads competing with e.g. Threads_lock, and threads 
>>>>>>>> waiting for GC and several other VM ops, could it just be really slow?
>>>>>>>>
>>>>>>>> /Robbin
>>>>>>>>
>>>>>>>>>
>>>>>>>>> David
>>>>>>>>>
>>>>>>>>> On 23/10/2018 5:58 PM, serguei.spitsyn at oracle.com wrote:
>>>>>>>>>> Hi David,
>>>>>>>>>>
>>>>>>>>>> You are right, thanks.
>>>>>>>>>> It means, this deadlock needs more analysis.
>>>>>>>>>> For completeness, the stack traces are in attachments.
>>>>>>>>>>
>>>>>>>>>> Thanks,
>>>>>>>>>> Serguei
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 10/23/18 00:43, David Holmes wrote:
>>>>>>>>>>> Hi Serguei,
>>>>>>>>>>>
>>>>>>>>>>> The JvmtiThreadState_lock is always acquired with safepoint checks 
>>>>>>>>>>> enabled, so all JavaThreads blocked trying to acquire it will be 
>>>>>>>>>>> _thread_blocked and so safepoint-safe and so won't be holding up the 
>>>>>>>>>>> safepoint.
>>>>>>>>>>>
>>>>>>>>>>> David
>>>>>>>>>>>
>>>>>>>>>>> On 23/10/2018 5:21 PM, serguei.spitsyn at oracle.com wrote:
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> I've added the seviceability-dev mailing list.
>>>>>>>>>>>> It can be interesting for the SVC folks. :)
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 10/22/18 22:14, Leonid Mesnik wrote:
>>>>>>>>>>>>> Hi
>>>>>>>>>>>>>
>>>>>>>>>>>>> Seems last version also crashes with 2 other different symptoms.
>>>>>>>>>>>>> http://java.se.oracle.com:10065/mdash/jobs/lmesnik-ks8-20181021-0638-7157/results?search=status%3Afailed+AND+-state%3Ainvalid 
>>>>>>>>>>>>> <http://java.se.oracle.com:10065/mdash/jobs/lmesnik-ks8-20181021-0638-7157/results?search=status:failed+AND+-state:invalid> 
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Also it might hangs with  stack attached.  Seems that test might be 
>>>>>>>>>>>>> blocked because it invoke 2 jvmti methods. Can jvmti agent invoke 
>>>>>>>>>>>>> jvmti methods from different threads?
>>>>>>>>>>>>
>>>>>>>>>>>> Yes, in general.
>>>>>>>>>>>> However, you have to be careful when using debugging features.
>>>>>>>>>>>> Below, one thread is enabling single stepping while another thread 
>>>>>>>>>>>> is being suspended.
>>>>>>>>>>>> Both are blocked at a safepoint which is Okay in general but not 
>>>>>>>>>>>> Okay if they hold any lock.
>>>>>>>>>>>> For instance, the thread #152 is holding the monitor JvmtiThreadState.
>>>>>>>>>>>>
>>>>>>>>>>>> Also, I see a couple of more threads that are interesting as well:
>>>>>>>>>>>>
>>>>>>>>>>>> Thread 159 (Thread 0x2ae40b78f700 (LWP 27962)):
>>>>>>>>>>>> #0  0x00002ae3927b5945 in pthread_cond_wait@@GLIBC_2.3.2 () from 
>>>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>>>> #1  0x00002ae393ba8d63 in os::PlatformEvent::park 
>>>>>>>>>>>> (this=this at entry=0x2ae3984c9100) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/posix/os_posix.cpp:1897 
>>>>>>>>>>>>
>>>>>>>>>>>> #2  0x00002ae393b50920 in ParkCommon (timo=0, ev=0x2ae3984c9100) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:399 
>>>>>>>>>>>>
>>>>>>>>>>>> #3  Monitor::ILock (this=0x2ae398024f10, Self=0x2ae3984c7800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:461 
>>>>>>>>>>>>
>>>>>>>>>>>> #4  0x00002ae393b512c1 in lock (Self=0x2ae3984c7is_ext_suspended800, 
>>>>>>>>>>>> this=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:910 
>>>>>>>>>>>>
>>>>>>>>>>>> #5  Monitor::lock (this=this at entry=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:919 
>>>>>>>>>>>>
>>>>>>>>>>>> #6  0x00002ae39350510c in MutexLocker (mutex=0x2ae398024f10, 
>>>>>>>>>>>> this=<synthetic pointer>) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutexLocker.hpp:182 
>>>>>>>>>>>>
>>>>>>>>>>>> #7  ciEnv::cache_jvmti_state (this=this at entry=0x2ae40b78eb30) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/ci/ciEnv.cpp:229
>>>>>>>>>>>> #8  0x00002ae3935d3294 in CompileBroker::invoke_compiler_on_method 
>>>>>>>>>>>> (task=task at entry=0x2ae48800ff40) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/compiler/compileBroker.cpp:2084 
>>>>>>>>>>>>
>>>>>>>>>>>> #9  0x00002ae3935d4f48 in CompileBroker::compiler_thread_loop () at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/compiler/compileBroker.cpp:1798 
>>>>>>>>>>>>
>>>>>>>>>>>> #10 0x00002ae393d7338a in JavaThread::thread_main_inner 
>>>>>>>>>>>> (this=this at entry=0x2ae3984c7800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1795 
>>>>>>>>>>>>
>>>>>>>>>>>> #11 0x00002ae393d736c6 in JavaThread::run (this=0x2ae3984c7800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1775 
>>>>>>>>>>>>
>>>>>>>>>>>> #12 0x00002ae393ba0070 in thread_native_entry 
>>>>>>>>>>>> (thread=0x2ae3984c7800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/linux/os_linux.cpp:698 
>>>>>>>>>>>>
>>>>>>>>>>>> #13 0x00002ae3927b1e25 in start_thread () from /lib64/libpthread.so.0
>>>>>>>>>>>> #14 0x00002ae392cc234d in clone () from /lib64/libc.so.6
>>>>>>>>>>>>
>>>>>>>>>>>> Thread 158 (Thread 0x2ae40b890700 (LWP 27963)):
>>>>>>>>>>>> #0  0x00002ae3927b5945 in pthread_cond_wait@@GLIBC_2.3.2 () from 
>>>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>>>> #1  0x00002ae393ba8d63 in os::PlatformEvent::park 
>>>>>>>>>>>> (this=this at entry=0x2ae3984cbb00) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/posix/os_posix.cpp:1897 
>>>>>>>>>>>>
>>>>>>>>>>>> #2  0x00002ae393b50920 in ParkCommon (timo=0, ev=0x2ae3984cbb00) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:399 
>>>>>>>>>>>>
>>>>>>>>>>>> #3  Monitor::ILock (this=0x2ae398024f10, Self=0x2ae3984ca800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:461 
>>>>>>>>>>>>
>>>>>>>>>>>> #4  0x00002ae393b512c1 in lock (Self=0x2ae3984ca800, 
>>>>>>>>>>>> this=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:910 
>>>>>>>>>>>>
>>>>>>>>>>>> #5  Monitor::lock (this=this at entry=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:919 
>>>>>>>>>>>>
>>>>>>>>>>>> #6  0x00002ae39350510c in MutexLocker (mutex=0x2ae398024f10, 
>>>>>>>>>>>> this=<synthetic pointer>) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutexLocker.hpp:182 
>>>>>>>>>>>>
>>>>>>>>>>>> #7  ciEnv::cache_jvmti_state (this=this at entry=0x2ae40b88fb30) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/ci/ciEnv.cpp:229
>>>>>>>>>>>> #8  0x00002ae3935d3294 in CompileBroker::invoke_compiler_on_method 
>>>>>>>>>>>> (task=task at entry=0x2ae49c00a670) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/compiler/compileBroker.cpp:2084 
>>>>>>>>>>>>
>>>>>>>>>>>> #9  0x00002ae3935d4f48 in CompileBroker::compiler_thread_loop () at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/compiler/compileBroker.cpp:1798 
>>>>>>>>>>>>
>>>>>>>>>>>> #10 0x00002ae393d7338a in JavaThread::thread_main_inner 
>>>>>>>>>>>> (this=this at entry=0x2ae3984ca800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1795 
>>>>>>>>>>>>
>>>>>>>>>>>> #11 0x00002ae393d736c6 in JavaThread::run (this=0x2ae3984ca800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1775 
>>>>>>>>>>>>
>>>>>>>>>>>> #12 0x00002ae393ba0070 in thread_native_entry 
>>>>>>>>>>>> (thread=0x2ae3984ca800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/linux/os_linux.cpp:698 
>>>>>>>>>>>>
>>>>>>>>>>>> #13 0x00002ae3927b1e25 in start_thread () from /lib64/libpthread.so.0
>>>>>>>>>>>> #14 0x00002ae392cc234d in clone () from /lib64/libc.so.6
>>>>>>>>>>>>
>>>>>>>>>>>> Thread 51 (Thread 0x2ae49549b700 (LWP 29678)):
>>>>>>>>>>>> #0  0x00002ae3927b5945 in pthread_cond_wait@@GLIBC_2.3.2 () from 
>>>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>>>> #1  0x00002ae393ba8d63 in os::PlatformEvent::park 
>>>>>>>>>>>> (this=this at entry=0x2ae460061c00) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/posix/os_posix.cpp:1897 
>>>>>>>>>>>>
>>>>>>>>>>>> #2  0x00002ae393b50920 in ParkCommon (timo=0, ev=0x2ae460061c00) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:399 
>>>>>>>>>>>>
>>>>>>>>>>>> #3  Monitor::ILock (this=0x2ae398024f10, Self=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:461 
>>>>>>>>>>>>
>>>>>>>>>>>> #4  0x00002ae393b512c1 in lock (Self=0x2ae4600c2800, 
>>>>>>>>>>>> this=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:910 
>>>>>>>>>>>>
>>>>>>>>>>>> #5  Monitor::lock (this=this at entry=0x2ae398024f10) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:919 
>>>>>>>>>>>>
>>>>>>>>>>>> #6  0x00002ae393999682 in MutexLocker (mutex=0x2ae398024f10, 
>>>>>>>>>>>> this=<synthetic pointer>) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutexLocker.hpp:182 
>>>>>>>>>>>>
>>>>>>>>>>>> #7  thread_started (thread=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEventController.cpp:668 
>>>>>>>>>>>>
>>>>>>>>>>>> #8  JvmtiEventController::thread_started (thread=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEventController.cpp:1027 
>>>>>>>>>>>>
>>>>>>>>>>>> #9  0x00002ae39399f3a0 in JvmtiExport::post_thread_start 
>>>>>>>>>>>> (thread=thread at entry=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiExport.cpp:1395 
>>>>>>>>>>>>
>>>>>>>>>>>> #10 0x00002ae393d737d8 in JavaThread::run (this=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1764 
>>>>>>>>>>>>
>>>>>>>>>>>> #11 0x00002ae393ba0070 in thread_native_entry 
>>>>>>>>>>>> (thread=0x2ae4600c2800) at 
>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/linux/os_linux.cpp:698 
>>>>>>>>>>>>
>>>>>>>>>>>> #12 0x00002ae3927b1e25 in start_thread () from /lib64/libpthread.so.0
>>>>>>>>>>>> #13 0x00002ae392cc234d in clone () from /lib64/libc.so.6
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> These two thread are blocked on the monitor JvmtiThreadState_lock in 
>>>>>>>>>>>> the function ciEnv::cache_jvmti_state().
>>>>>>>>>>>> Also, there are many threads (like #51) that are executing 
>>>>>>>>>>>> JvmtiExport::post_thread_start and blocked on the same monitor.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Now, the question is why this safepoint can not start?
>>>>>>>>>>>> What thread is blocking it? Or in reverse, what thread this 
>>>>>>>>>>>> safepoint is waiting for?
>>>>>>>>>>>>
>>>>>>>>>>>> I think, this safepoint operation is waiting for all threads that 
>>>>>>>>>>>> are blocked on the JvmtiThreadState_lock.
>>>>>>>>>>>>
>>>>>>>>>>>> Conclusion:
>>>>>>>>>>>>
>>>>>>>>>>>> The deadlock is:
>>>>>>>>>>>>
>>>>>>>>>>>> Thread #152:
>>>>>>>>>>>>    - grabbed the monitor JvmtiThreadState_lock
>>>>>>>>>>>>    - blocked in the VM_GetCurrentLocation in the function 
>>>>>>>>>>>> JvmtiEnvThreadState::reset_current_location()
>>>>>>>>>>>>
>>>>>>>>>>>> Many other threads:
>>>>>>>>>>>>    - blocked on the monitor JvmtiThreadState_lock
>>>>>>>>>>>>    - can not reach the blocked at a safepoint state (all threads 
>>>>>>>>>>>> have to reach this state for this safepoint to happen)
>>>>>>>>>>>>
>>>>>>>>>>>> It seems to me, this is a bug which has to be filed.
>>>>>>>>>>>>
>>>>>>>>>>>> My guess is that this will stop to reproduce after if you turn off 
>>>>>>>>>>>> the single stepping for thread #152.
>>>>>>>>>>>> Please, let me know about the results.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> Assuming that crashes look like VM bugs I think it make sense to 
>>>>>>>>>>>>> integrate jvmti changes but *don't* enabled jvmti module by default.
>>>>>>>>>>>>
>>>>>>>>>>>> This one is a deadlock.
>>>>>>>>>>>> However, the root cause is a race condition that can potentially 
>>>>>>>>>>>> result in both deadlocks and crashes.
>>>>>>>>>>>> So, I'm curious if you observed crashes as well.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> And add to more tests with jvmti enabled.
>>>>>>>>>>>>> So anyone could easily run them to reproduce crashes.  This test 
>>>>>>>>>>>>> would be out of CI to don't introduce any bugs. Does it make sense?
>>>>>>>>>>>>>
>>>>>>>>>>>>> Consider hang - I think that it might be product bug since I don't 
>>>>>>>>>>>>> see any locking on my monitors. But I am not sure. Is it possible 
>>>>>>>>>>>>> that any my code jvmti agent prevent VM to get into safepoint?
>>>>>>>>>>>>> Could we discuss it tomorrow or his week when you have a time?
>>>>>>>>>>>>
>>>>>>>>>>>> Yes, of course.
>>>>>>>>>>>> Let's find some time tomorrow.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> Any suggestion how to diagnose deadlock would be great.
>>>>>>>>>>>>
>>>>>>>>>>>> Analysis of stack traces is needed.
>>>>>>>>>>>> It is non-trivial in this particular case as there are so many 
>>>>>>>>>>>> threads executed at the same time.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>> Part of stack trace with 2 my threads only:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thread 136 (Thread 0x2ae494100700 (LWP 28023)):
>>>>>>>>>>>>> #0  0x00002ae3927b5945 in pthread_cond_wait@@GLIBC_2.3.2 () from 
>>>>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>>>>> #1  0x00002ae393ba8d63 in os::PlatformEvent::park 
>>>>>>>>>>>>> (this=this at entry=0x2ae454005800) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/posix/os_posix.cpp:1897 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #2  0x00002ae393b50cf8 in ParkCommon (timo=0, ev=0x2ae454005800) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:399 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #3  Monitor::IWait (this=this at entry=0x2ae398023c10, 
>>>>>>>>>>>>> Self=Self at entry=0x2ae454004800, timo=timo at entry=0) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:76\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> 8
>>>>>>>>>>>>> #4  0x00002ae393b51f2e in Monitor::wait 
>>>>>>>>>>>>> (this=this at entry=0x2ae398023c10, no_safepoint_check=<optimized 
>>>>>>>>>>>>> out>, timeout=timeout at entry=0, 
>>>>>>>>>>>>> as_suspend_equivalent=as_suspend_equivalent at en\
>>>>>>>>>>>>> try=false) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:1106 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #5  0x00002ae393de7867 in VMThread::execute 
>>>>>>>>>>>>> (op=op at entry=0x2ae4940ffb10) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/vmThread.cpp:657 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #6  0x00002ae393d6a3bd in JavaThread::java_suspend 
>>>>>>>>>>>>> (this=this at entry=0x2ae3985f2000) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:2321 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #7  0x00002ae3939ad7e1 in JvmtiSuspendControl::suspend 
>>>>>>>>>>>>> (java_thread=java_thread at entry=0x2ae3985f2000) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiImpl.cpp:8\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> 47
>>>>>>>>>>>>> #8  0x00002ae3939887ae in JvmtiEnv::SuspendThread 
>>>>>>>>>>>>> (this=this at entry=0x2ae39801b270, java_thread=0x2ae3985f2000) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiE\
>>>>>>>>>>>>> nv.cpp:955
>>>>>>>>>>>>> #9  0x00002ae39393a8c6 in jvmti_SuspendThread (env=0x2ae39801b270, 
>>>>>>>>>>>>> thread=0x2ae49929fdf8) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/build/linux-x64/hotspot/variant-server/gensrc/jvmtifiles\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> /jvmtiEnter.cpp:527
>>>>>>>>>>>>> #10 0x00002ae394d973ee in agent_sampler (jvmti=0x2ae39801b270, 
>>>>>>>>>>>>> env=<optimized out>, p=<optimized out>) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/closed/test/hotspot/jtreg/applications/kitc\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> hensink/process/stress/modules/libJvmtiStressModule.c:274
>>>>>>>>>>>>> #11 0x00002ae3939ab24d in call_start_function (this=0x2ae454004800) 
>>>>>>>>>>>>> at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiImpl.cpp:85 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #12 JvmtiAgentThread::start_function_wrapper 
>>>>>>>>>>>>> (thread=0x2ae454004800, __the_thread__=<optimized out>) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiImpl.cpp:79 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #13 0x00002ae393d7338a in JavaThread::thread_main_inner 
>>>>>>>>>>>>> (this=this at entry=0x2ae454004800) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1795 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #14 0x00002ae393d736c6 in JavaThread::run (this=0x2ae454004800) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/thread.cpp:1775 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #15 0x00002ae393ba0070 in thread_native_entry 
>>>>>>>>>>>>> (thread=0x2ae454004800) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/linux/os_linux.cpp:698 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #16 0x00002ae3927b1e25 in start_thread () from /lib64/libpthread.so.0
>>>>>>>>>>>>> #17 0x00002ae392cc234d in clone () from /lib64/libc.so.6
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thread 152 (Thread 0x2ae427060700 (LWP 27995)):
>>>>>>>>>>>>> #0  0x00002ae3927b5945 in pthread_cond_wait@@GLIBC_2.3.2 () from 
>>>>>>>>>>>>> /lib64/libpthread.so.0
>>>>>>>>>>>>> #1  0x00002ae393ba8d63 in os::PlatformEvent::park 
>>>>>>>>>>>>> (this=this at entry=0x2ae3985e7400) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/os/posix/os_posix.cpp:1897 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #2  0x00002ae393b50cf8 in ParkCommon (timo=0, ev=0x2ae3985e7400) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:399 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #3  Monitor::IWait (this=this at entry=0x2ae398023c10, 
>>>>>>>>>>>>> Self=Self at entry=0x2ae3985e6000, timo=timo at entry=0) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:76\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> 8
>>>>>>>>>>>>> #4  0x00002ae393b51f2e in Monitor::wait 
>>>>>>>>>>>>> (this=this at entry=0x2ae398023c10, no_safepoint_check=<optimized 
>>>>>>>>>>>>> out>, timeout=timeout at entry=0, 
>>>>>>>>>>>>> as_suspend_equivalent=as_suspend_equivalent at en\
>>>>>>>>>>>>> try=false) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/mutex.cpp:1106 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #5  0x00002ae393de7867 in VMThread::execute (op=0x2ae42705f500) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/runtime/vmThread.cpp:657 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #6  0x00002ae3939965f3 in 
>>>>>>>>>>>>> JvmtiEnvThreadState::reset_current_location 
>>>>>>>>>>>>> (this=this at entry=0x2ae6bc000d80, 
>>>>>>>>>>>>> event_type=event_type at entry=JVMTI_EVENT_SINGLE_STEP, 
>>>>>>>>>>>>> enabled=enabled at entry=tr\
>>>>>>>>>>>>> ue) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEnvThreadState.cpp:312 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #7  0x00002ae393997acf in recompute_env_thread_enabled 
>>>>>>>>>>>>> (state=0x2ae6bc000cd0, ets=0x2ae6bc000d80) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEventControlle\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> r.cpp:490
>>>>>>>>>>>>> #8  JvmtiEventControllerPrivate::recompute_thread_enabled 
>>>>>>>>>>>>> (state=state at entry=0x2ae6bc000cd0) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEventController.cpp\ 
>>>>>>>>>>>>>
>>>>>>>>>>>>> :523
>>>>>>>>>>>>> #9  0x00002ae393998168 in 
>>>>>>>>>>>>> JvmtiEventControllerPrivate::recompute_enabled () at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEventController.cpp:598 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #10 0x00002ae39399a244 in set_user_enabled (enabled=true, 
>>>>>>>>>>>>> event_type=JVMTI_EVENT_SINGLE_STEP, thread=0x0, env=0x2ae39801b270) 
>>>>>>>>>>>>> at /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/sha\
>>>>>>>>>>>>> re/prims/jvmtiEventController.cpp:818
>>>>>>>>>>>>> #11 JvmtiEventController::set_user_enabled (env=0x2ae39801b270, 
>>>>>>>>>>>>> thread=0x0, event_type=JVMTI_EVENT_SINGLE_STEP, enabled=<optimized 
>>>>>>>>>>>>> out>) at /scratch/lmesnik/ws/hs-bigapps/open/src/\
>>>>>>>>>>>>> hotspot/share/prims/jvmtiEventController.cpp:963
>>>>>>>>>>>>> #12 0x00002ae393987d2d in JvmtiEnv::SetEventNotificationMode 
>>>>>>>>>>>>> (this=this at entry=0x2ae39801b270, mode=mode at entry=JVMTI_ENABLE, 
>>>>>>>>>>>>> event_type=event_type at entry=JVMTI_EVENT_SINGLE_STEP, eve\
>>>>>>>>>>>>> nt_thread=event_thread at entry=0x0) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiEnv.cpp:543 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #13 0x00002ae3939414eb in jvmti_SetEventNotificationMode 
>>>>>>>>>>>>> (env=0x2ae39801b270, mode=mode at entry=JVMTI_ENABLE, 
>>>>>>>>>>>>> event_type=event_type at entry=JVMTI_EVENT_SINGLE_STEP, 
>>>>>>>>>>>>> event_thread=event_\
>>>>>>>>>>>>> thread at entry=0x0) at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/build/linux-x64/hotspot/variant-server/gensrc/jvmtifiles/jvmtiEnter.cpp:5389 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #14 0x00002ae394d97989 in enable_events () at 
>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/closed/test/hotspot/jtreg/applications/kitchensink/process/stress/modules/libJvmtiStressModule.c:519 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #15 0x00002ae394d98070 in 
>>>>>>>>>>>>> Java_applications_kitchensink_process_stress_modules_JvmtiStressModule_startIteration 
>>>>>>>>>>>>> (env=<optimized out>, this=<optimized out>) at /scratch/lmesnik/ws/h\
>>>>>>>>>>>>> s-bigapps/closed/test/hotspot/jtreg/applications/kitchensink/process/stress/modules/libJvmtiStressModule.c:697 
>>>>>>>>>>>>>
>>>>>>>>>>>>> #16 0x00002ae3a43ef257 in ?? ()
>>>>>>>>>>>>> #17 0x00002ae3a43eede1 in ?? ()
>>>>>>>>>>>>> #18 0x00002ae42705f878 in ?? ()
>>>>>>>>>>>>> #19 0x00002ae40ad334e0 in ?? ()
>>>>>>>>>>>>> #20 0x00002ae42705f8e0 in ?? ()
>>>>>>>>>>>>> #21 0x00002ae40ad33c68 in ?? ()
>>>>>>>>>>>>> #22 0x0000000000000000 in ?? ()
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Serguei
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Leonid
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Oct 9, 2018, at 4:52 PM, serguei.spitsyn at oracle.com 
>>>>>>>>>>>>>> <mailto:serguei.spitsyn at oracle.com> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi Leonid,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> There is an existing bug:
>>>>>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8043571
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Thanks,
>>>>>>>>>>>>>> Serguei
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 10/9/18 16:11, Leonid Mesnik wrote:
>>>>>>>>>>>>>>> Hi
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> During fixing kitchensink I get
>>>>>>>>>>>>>>> assert(_cur_stack_depth == count_frames()) failed: 
>>>>>>>>>>>>>>> cur_stack_depth out of sync
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Do you know if i might be bug in my jvmti agent?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Leonid
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> #
>>>>>>>>>>>>>>> # A fatal error has been detected by the Java Runtime Environment:
>>>>>>>>>>>>>>> #
>>>>>>>>>>>>>>> #  Internal Error 
>>>>>>>>>>>>>>> (/scratch/lmesnik/ws/hs-bigapps/open/src/hotspot/share/prims/jvmtiThreadState.cpp:277), 
>>>>>>>>>>>>>>> pid=13926, tid=13962
>>>>>>>>>>>>>>> #  assert(_cur_stack_depth == count_frames()) failed: 
>>>>>>>>>>>>>>> cur_stack_depth out of sync
>>>>>>>>>>>>>>> #
>>>>>>>>>>>>>>> # JRE version: Java(TM) SE Runtime Environment (12.0) (fastdebug 
>>>>>>>>>>>>>>> build 12-internal+0-2018-10-08-2342517.lmesnik.hs-bigapps)
>>>>>>>>>>>>>>> # Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 
>>>>>>>>>>>>>>> 12-internal+0-2018-10-08-2342517.lmesnik.hs-bigapps, mixed mode, 
>>>>>>>>>>>>>>> tiered, compressed oops, g1 gc, linux-amd64)
>>>>>>>>>>>>>>> # Core dump will be written. Default location: Core dumps may be 
>>>>>>>>>>>>>>> processed with "/usr/libexec/abrt-hook-ccpp %s %c %p %u %g %t e 
>>>>>>>>>>>>>>> %P %I %h" (or dumping to 
>>>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/build/linux-x64/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_KitchensinkSanity_java/scratch/0/core.13926) 
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> #
>>>>>>>>>>>>>>> # If you would like to submit a bug report, please visit:
>>>>>>>>>>>>>>> # http://bugreport.java.com/bugreport/crash.jsp
>>>>>>>>>>>>>>> #
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> ---------------  S U M M A R Y ------------
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Command Line: -XX:MaxRAMPercentage=2 -XX:MaxRAMPercentage=50 
>>>>>>>>>>>>>>> -XX:+CrashOnOutOfMemoryError -Djava.net.preferIPv6Addresses=false 
>>>>>>>>>>>>>>> -XX:-PrintVMOptions -XX:+DisplayVMOutputToStderr -XX:+UsePerfData 
>>>>>>>>>>>>>>> -Xlog:gc*,gc+heap=debug:gc.log:uptime,timemillis,level,tags 
>>>>>>>>>>>>>>> -XX:+DisableExplicitGC -XX:+PrintFlagsFinal 
>>>>>>>>>>>>>>> -XX:+StartAttachListener -XX:NativeMemoryTracking=detail 
>>>>>>>>>>>>>>> -XX:+FlightRecorder --add-exports=java.base/java.lang=ALL-UNNAMED 
>>>>>>>>>>>>>>> --add-opens=java.base/java.lang=ALL-UNNAMED 
>>>>>>>>>>>>>>> --add-exports=java.xml/com.sun.org.apache.xerces.internal.parsers=ALL-UNNAMED 
>>>>>>>>>>>>>>> --add-exports=java.xml/com.sun.org.apache.xerces.internal.util=ALL-UNNAMED 
>>>>>>>>>>>>>>> -Djava.io.tmpdir=/scratch/lmesnik/ws/hs-bigapps/build/linux-x64/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_KitchensinkSanity_java/scratch/0/java.io.tmpdir 
>>>>>>>>>>>>>>> -Duser.home=/scratch/lmesnik/ws/hs-bigapps/build/linux-x64/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_KitchensinkSanity_java/scratch/0/user.home 
>>>>>>>>>>>>>>> -agentpath:/scratch/lmesnik/ws/hs-bigapps/build/linux-x64/images/test/hotspot/jtreg/native/libJvmtiStressModule.so 
>>>>>>>>>>>>>>> applications.kitchensink.process.stress.Main 
>>>>>>>>>>>>>>> /scratch/lmesnik/ws/hs-bigapps/build/linux-x64/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_KitchensinkSanity_java/scratch/0/kitchensink.final.properties 
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Host: scaaa118.us.oracle.com <http://scaaa118.us.oracle.com>, 
>>>>>>>>>>>>>>> Intel(R) Xeon(R) CPU E5-2690 0 @ 2.90GHz, 32 cores, 235G, Oracle 
>>>>>>>>>>>>>>> Linux Server release 7.3
>>>>>>>>>>>>>>> Time: Tue Oct  9 16:06:07 2018 PDT elapsed time: 31 seconds (0d 
>>>>>>>>>>>>>>> 0h 0m 31s)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> ---------------  T H R E A D  ---------------
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Current thread (0x00002af3dc6ac800):  VMThread "VM Thread" 
>>>>>>>>>>>>>>> [stack: 0x00002af44f10a000,0x00002af44f20a000] [id=13962] 
>>>>>>>>>>>>>>> _threads_hazard_ptr=0x00002af4ac090eb0, 
>>>>>>>>>>>>>>> _nested_threads_hazard_ptr_cnt=0
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Stack: [0x00002af44f10a000,0x00002af44f20a000], 
>>>>>>>>>>>>>>>  sp=0x00002af44f208720,  free space=1017k
>>>>>>>>>>>>>>> Native frames: (J=compiled Java code, A=aot compiled Java code, 
>>>>>>>>>>>>>>> j=interpreted, Vv=VM code, C=native code)
>>>>>>>>>>>>>>> V  [libjvm.so+0x18c4923]  VMError::report_and_die(int, char 
>>>>>>>>>>>>>>> const*, char const*, __va_list_tag*, Thread*, unsigned char*, 
>>>>>>>>>>>>>>> void*, void*, char const*, int, unsigned long)+0x2c3
>>>>>>>>>>>>>>> V  [libjvm.so+0x18c56ef]  VMError::report_and_die(Thread*, void*, 
>>>>>>>>>>>>>>> char const*, int, char const*, char const*, __va_list_tag*)+0x2f
>>>>>>>>>>>>>>> V  [libjvm.so+0xb55aa0]  report_vm_error(char const*, int, char 
>>>>>>>>>>>>>>> const*, char const*, ...)+0x100
>>>>>>>>>>>>>>> V  [libjvm.so+0x11f2cfe]  JvmtiThreadState::cur_stack_depth()+0x14e
>>>>>>>>>>>>>>> V  [libjvm.so+0x11f3257] 
>>>>>>>>>>>>>>>  JvmtiThreadState::update_for_pop_top_frame()+0x27
>>>>>>>>>>>>>>> V  [libjvm.so+0x119af99]  VM_UpdateForPopTopFrame::doit()+0xb9
>>>>>>>>>>>>>>> V  [libjvm.so+0x1908982]  VM_Operation::evaluate()+0x132
>>>>>>>>>>>>>>> V  [libjvm.so+0x19040be] 
>>>>>>>>>>>>>>>  VMThread::evaluate_operation(VM_Operation*) [clone 
>>>>>>>>>>>>>>> .constprop.51]+0x18e
>>>>>>>>>>>>>>> V  [libjvm.so+0x1904960]  VMThread::loop()+0x4c0
>>>>>>>>>>>>>>> V  [libjvm.so+0x1904f53]  VMThread::run()+0xd3
>>>>>>>>>>>>>>> V  [libjvm.so+0x14e8300]  thread_native_entry(Thread*)+0x100
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> VM_Operation (0x00002af4d8502910): UpdateForPopTopFrame, mode: 
>>>>>>>>>>>>>>> safepoint, requested by thread 0x00002af4dc008800
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>
>>>>>>
>>>
> 


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