On Tue, 28 Mar 2023 18:57:23 GMT, Serguei Spitsyn <[email protected]> wrote:
>> The fix is to enable virtual threads support for late binding JVMTI agents.
>> The fix includes:
>> - New function `JvmtiEnvBase::enable_virtual_threads_notify_jvmti()` which
>> does enabling JVMTI VTMS transition notifications in case of agent loaded
>> into running VM. This function executes a VM operation counting VTMS
>> transition bits in all `JavaThread`'s to correctly set the static counter
>> `_VTMS_transition_count` needed for VTMS transition protocol.
>> - New function `JvmtiEnvBase::disable_virtual_threads_notify_jvmti()` which
>> is needed for testing. It is used by the `WhiteBox` API.
>> - New WhiteBox function `WB_SetVirtualThreadsNotifyJvmtiMode(JNIEnv* env,
>> jobject wb, jboolean enable)` needed for testing of this update.
>> - New regression test: `serviceability/jvmti/vthread/ToggleNotifyJvmtiTest`
>>
>> Testing:
>> - New test: `serviceability/jvmti/vthread/ToggleNotifyJvmtiTest`
>> - The originally failed tests are expected to pass now:
>> `runtime/vthread/RedefineClass.java`
>> `runtime/vthread/TestObjectAllocationSampleEvent.java`
>> - In progress: Run the tiers 1-6 to make sure there are no regression.
>
> Serguei Spitsyn has updated the pull request incrementally with one
> additional commit since the last revision:
>
> fixed trailing spaces in two files
Changes requested by lmesnik (Reviewer).
src/hotspot/share/prims/jvmtiEnvBase.cpp line 1547:
> 1545: JvmtiThreadState* ct_state =
> java_lang_Thread::jvmti_thread_state(jt->threadObj());
> 1546: JvmtiThreadState* vt_state = vt_oop != nullptr ?
> java_lang_Thread::jvmti_thread_state(vt_oop) : nullptr;
> 1547: bool virt = vt_oop != nullptr && vt_oop != ct_oop;
You can move it inside if() in line 1554
src/hotspot/share/prims/jvmtiEnvBase.cpp line 1554:
> 1552: // Correct jt->jvmti_thread_state() and jt->jvmti_vthread() if
> necessary.
> 1553: // It was not maintained while notifyJvmti was disabled.
> 1554: if (jt_state != ct_state && jt_state != vt_state) {
Is it possible that jt_state == ct_state while the virtual thread is executed
or vice versa? Just because jvmtt_state is outdated.
Shouldn't we always update (set to null) link/ jvmti_vthread if _enabled ==
true?
test/hotspot/jtreg/serviceability/jvmti/vthread/ToggleNotifyJvmtiTest/libToggleNotifyJvmtiTest.cpp
line 46:
> 44: RawMonitorLocker agent_locker(jvmti, jni, agent_lock);
> 45:
> 46: vthread_started_cnt++;
Wouldn't it be better to use std::atomic<int> instead RawMonitorLocker here to
reduce sync time?
-------------
PR Review: https://git.openjdk.org/jdk/pull/13133#pullrequestreview-1362120493
PR Review Comment: https://git.openjdk.org/jdk/pull/13133#discussion_r1151298663
PR Review Comment: https://git.openjdk.org/jdk/pull/13133#discussion_r1151334153
PR Review Comment: https://git.openjdk.org/jdk/pull/13133#discussion_r1151329179
