RFR: 8297286: runtime/vthread tests crashing after JDK-8296324 [v8]

[Serguei Spitsyn]

On Tue, 28 Mar 2023 18:57:23 GMT, Serguei Spitsyn <sspitsyn at openjdk.org> 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

Pushed a couple of updates which include:
(1) Addressed review comments:
   - fixed minor issues in `libToggleNotifyJvmtiTest.cpp`: added volatile specifier and removed unneeded static variable
   - fixed the typo in `disable_virtual_threads_notify_jvmti`
   - added comments  for two new functions in `jvmtiEnvBase` (enabling and disabling notifyJvmti events)
   - added comments to `ToggleNotifyJvmtiTest.java`

(2) Refactored the `ToggleNotifyJvmtiTest.java` to run isolated sequential test cycles for the sake of `disable_virtual_threads_notify_jvmti` safety (no virtual threads are allowed to run when it is executed)

(3) Extended `libToggleNotifyJvmtiTest.cpp` to request more JVMTI events: `VirtualThreadEnd`, `ThreadStart` and `ThreadEnd`

(4) Other updates:
 - updated `JVM_VirtualThreadHideFrames` and `LibraryCallKit::inline_native_notify_jvmti_hide` to always (unconditionally) set the temporary VTMS transition bit to avoid asserts
 - renamed VMop: `InitNotifyJvmtiEventsMode` => `SetNotifyJvmtiEventsMode`
 - updated `VM_SetNotifyJvmtiEventsMode` to correct `jt->jvmti_thread_state()` and `jt->jvmti_vthread()` if necessary (needed to fix `JvmtiThreadState` double-deallocation issue)
 
 I hope that all review comments have been addressed now. Please, let me know if anything is missed.
 The mach5 tiers 1-6 tuns are good.

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PR Comment: https://git.openjdk.org/jdk/pull/13133#issuecomment-1487477975