On Sun, 19 Nov 2023 09:22:43 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> @sspitsyn - Please point me at the code where these JavaThreads are newly >> created? > > @dcubed-ojdk > I don't know FJP implementation well enough to point at the code where it > happens. However, I observe that new `JavaThread `is being created between > two points of the execution path. > - First point is in the `JvmtiEventControllerPrivate::recompute_enabled()` > at the line where a `ThreadsListHandle` is set. I've added a trap checking if > any `JavaThread` pointed by `state->get_thread()` is not protected by the > `tlh`. I can see this trap is not fired (I can't say it has never been fired). > - Second point is in the > `JvmtiEventControllerPrivate::enter_interp_only_mode()`. If a > `ThreadsListHandle` is NOT set then I can observe a `JavaThread` referenced > by the state->get_thread() which is not protected by any TLH. It a TLH added > into `JvmtiEventControllerPrivate::enter_interp_only_mode()` then this > `JavaThread` is observed as protected by TLH. > I can provide a full stack trace for this `JavaThread` consisting of two > parts: carrier thread and virtual thread frames. The name of carrier thread > is `ForkJoinPool-1-worker-1`. The virtual thread is a tested virtual thread. > The thread dump looks las below: > > DBG: enter_interp_only_mode: target: 0x7f93f8043d00 <unnamed> virt: 1 > carrier: ForkJoinPool-1-worker-1 > DBG: ##### NATIVE stacktrace of JavaThread: 0x7f93f8043d00 ##### > Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native > code) > j fieldacc02.check(Ljava/lang/Object;)I+0 > j fieldacc02.lambda$testVirtualThread$0()V+12 > j fieldacc02$$Lambda+0x00007f943b001428.run()V+0 > j java.lang.Thread.runWith(Ljava/lang/Object;Ljava/lang/Runnable;)V+5 > java.base@22-internal > j java.lang.VirtualThread.run(Ljava/lang/Runnable;)V+66 java.base@22-internal > j java.lang.VirtualThread$VThreadContinuation$1.run()V+8 > java.base@22-internal > j jdk.internal.vm.Continuation.enter0()V+4 java.base@22-internal > j jdk.internal.vm.Continuation.enter(Ljdk/internal/vm/Continuation;Z)V+1 > java.base@22-internal > J 124 > jdk.internal.vm.Continuation.enterSpecial(Ljdk/internal/vm/Continuation;ZZ)V > java.base@22-internal (0 bytes) @ 0x00007f94c7cdf744 > [0x00007f94c7cdf5e0+0x0000000000000164] > j jdk.internal.vm.Continuation.run()V+122 java.base@22-internal > j java.lang.VirtualThread.runContinuation()V+70 java.base@22-internal > j java.lang.VirtualThread$$Lambda+0x00007f943b0496c0.run()V+4 > java.base@22-internal > j > java.util.concurrent.ForkJoinTask$RunnableExecuteAction.compute()Ljava/lang/Void;+4 > java.base@22-internal > j java.util.concurrent.ForkJoinTask$RunnableExecuteAction.compute(... The stack trace of current thread (where the assert was fired) can explain what is going on a little bit: Current thread (0x00007f93f8043d00): JavaThread "ForkJoinPool-1-worker-1" daemon [_thread_in_vm, id=16779, stack(0x00007f948a597000,0x00007f948a697000) (1024K)] Stack: [0x00007f948a597000,0x00007f948a697000], sp=0x00007f948a6949e0, free space=1014k Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code) V [libjvm.so+0x117937d] JvmtiEventControllerPrivate::enter_interp_only_mode(JvmtiThreadState*)+0x45d (jvmtiEventController.cpp:402) V [libjvm.so+0x1179520] JvmtiEventControllerPrivate::recompute_thread_enabled(JvmtiThreadState*) [clone .part.0]+0x190 (jvmtiEventController.cpp:632) V [libjvm.so+0x117a1e1] JvmtiEventControllerPrivate::thread_started(JavaThread*)+0x351 (jvmtiEventController.cpp:1174) V [libjvm.so+0x117e608] JvmtiExport::get_jvmti_thread_state(JavaThread*)+0x98 (jvmtiExport.cpp:424) V [libjvm.so+0x118a86c] JvmtiExport::post_field_access(JavaThread*, Method*, unsigned char*, Klass*, Handle, _jfieldID*)+0x6c (jvmtiExport.cpp:2214) V [libjvm.so+0x118b3a1] JvmtiExport::post_field_access_by_jni(JavaThread*, oop, Klass*, _jfieldID*, bool)+0x321 (jvmtiExport.cpp:2202) V [libjvm.so+0x118b4e9] JvmtiExport::jni_GetField_probe(JavaThread*, _jobject*, oop, Klass*, _jfieldID*, bool)+0x79 (jvmtiExport.cpp:2168) V [libjvm.so+0xf83847] jni_GetStaticBooleanField+0x257 (jni.cpp:2047) C [libfieldacc02.so+0x379b] Java_fieldacc02_check+0x6b (jni.h:1546) j fieldacc02.check(Ljava/lang/Object;)I+0 j fieldacc02.lambda$testVirtualThread$0()V+12 j fieldacc02$$Lambda+0x00007f943b001428.run()V+0 j java.lang.Thread.runWith(Ljava/lang/Object;Ljava/lang/Runnable;)V+5 java.base@22-internal j java.lang.VirtualThread.run(Ljava/lang/Runnable;)V+66 java.base@22-internal j java.lang.VirtualThread$VThreadContinuation$1.run()V+8 java.base@22-internal j jdk.internal.vm.Continuation.enter0()V+4 java.base@22-internal j jdk.internal.vm.Continuation.enter(Ljdk/internal/vm/Continuation;Z)V+1 java.base@22-internal J 124 jdk.internal.vm.Continuation.enterSpecial(Ljdk/internal/vm/Continuation;ZZ)V java.base@22-internal (0 bytes) @ 0x00007f94c7cdf744 [0x00007f94c7cdf5e0+0x0000000000000164] j jdk.internal.vm.Continuation.run()V+122 java.base@22-internal j java.lang.VirtualThread.runContinuation()V+70 java.base@22-internal j java.lang.VirtualThread$$Lambda+0x00007f943b0496c0.run()V+4 java.base@22-internal j java.util.concurrent.ForkJoinTask$RunnableExecuteAction.compute()Ljava/lang/Void;+4 java.base@22-internal j java.util.concurrent.ForkJoinTask$RunnableExecuteAction.compute()Ljava/lang/Object;+1 java.base@22-internal j java.util.concurrent.ForkJoinTask$InterruptibleTask.exec()Z+51 java.base@22-internal j java.util.concurrent.ForkJoinTask.doExec()V+10 java.base@22-internal j java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(Ljava/util/concurrent/ForkJoinTask;Ljava/util/concurrent/ForkJoinPool$WorkQueue;I)V+49 java.base@22-internal j java.util.concurrent.ForkJoinPool.scan(Ljava/util/concurrent/ForkJoinPool$WorkQueue;JI)J+271 java.base@22-internal j java.util.concurrent.ForkJoinPool.runWorker(Ljava/util/concurrent/ForkJoinPool$WorkQueue;)V+68 java.base@22-internal j java.util.concurrent.ForkJoinWorkerThread.run()V+31 java.base@22-internal v ~StubRoutines::call_stub 0x00007f94c7505d21 V [libjvm.so+0xe7b719] JavaCalls::call_helper(JavaValue*, methodHandle const&, JavaCallArguments*, JavaThread*)+0x4a9 (javaCalls.cpp:415) V [libjvm.so+0xe7bdd5] JavaCalls::call_virtual(JavaValue*, Klass*, Symbol*, Symbol*, JavaCallArguments*, JavaThread*)+0x345 (javaCalls.cpp:329) V [libjvm.so+0xe7bff6] JavaCalls::call_virtual(JavaValue*, Handle, Klass*, Symbol*, Symbol*, JavaThread*)+0x76 (javaCalls.cpp:191) V [libjvm.so+0xfd9723] thread_entry(JavaThread*, JavaThread*)+0x93 (jvm.cpp:2937) V [libjvm.so+0xeb06ac] JavaThread::thread_main_inner()+0xcc (javaThread.cpp:720) V [libjvm.so+0x1789496] Thread::call_run()+0xb6 (thread.cpp:220) V [libjvm.so+0x1493b27] thread_native_entry(Thread*)+0x127 (os_linux.cpp:787) ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16686#discussion_r1398365938
