On Wed, 21 Jan 2026 20:11:53 GMT, Serguei Spitsyn <[email protected]> wrote:
>> An asynchronous handshake operation (`ThreadSelfSuspensionHandshakeClosure`)
>> can be installed when the target thread is not in a `MountUnmountDisabler`
>> scope. But the target thread can enter such scope by the time the operation
>> is self-processed by the target thread.
>>
>> This is fixed by a small tweak in the function
>> `HandshakeOperation* HandshakeState::get_op_for_self(bool allow_suspend,
>> bool check_async_exception)`.
>> The tweak is to skip a `HandshakeOperation` if
>> `_handshakee->is_vthread_transition_disabler() == true`, so the same
>> temporary suspension disabling mechanism would be used as for
>> `_handshakee->is_disable_suspend() == true`.
>>
>> All other changes are to move the `is_vthread_transition_disabler()` out of
>> DEBUG to product.
>>
>> Testing:
>> - In progress: mach5 tiers 1-6
>
> Serguei Spitsyn has updated the pull request incrementally with one
> additional commit since the last revision:
>
> review: restored the original assert with a different message
Looks good.
A couple of small nits, feel free to ignore them.
src/hotspot/share/runtime/handshake.cpp line 525:
> 523: #if INCLUDE_JVMTI
> 524: if (allow_suspend && (_handshakee->is_disable_suspend() ||
> _handshakee->is_vthread_transition_disabler())) {
> 525: // filter out suspend operations while JavaThread is in
> disable_suspend mode
does it makes sense to update comment to
// filter out suspend operations while JavaThread is in disable_suspend mode
or in transition
or something more generic
// check if JavaThread can be suspended in this handshake
test/hotspot/jtreg/serviceability/jvmti/vthread/ThreadStateTest2/libThreadStateTest2.cpp
line 63:
> 61: JNIEXPORT void JNICALL
> 62: Java_ThreadStateTest2_setMonitorContendedMode(JNIEnv* jni, jclass klass,
> jboolean enable) {
> 63: jvmtiError err = jvmti->SetEventNotificationMode(enable ? JVMTI_ENABLE
> : JVMTI_DISABLE, JVMTI_EVENT_MONITOR_CONTENDED_ENTER, nullptr);
You can use
set_event_notification_mode(jvmtiEnv*, ... )
from jvmti_common.h
-------------
Marked as reviewed by lmesnik (Reviewer).
PR Review: https://git.openjdk.org/jdk/pull/28740#pullrequestreview-3689496071
PR Review Comment: https://git.openjdk.org/jdk/pull/28740#discussion_r2714417725
PR Review Comment: https://git.openjdk.org/jdk/pull/28740#discussion_r2714441116
