On Tue, 20 Jan 2026 20:57:29 GMT, Patricio Chilano Mateo
<[email protected]> wrote:
>> Serguei Spitsyn has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> 8375362: deadlock with unmount of suspended virtual thread interrupting
>> another virtual thread
>
> src/hotspot/share/runtime/javaThread.cpp line 1186:
>
>> 1184: bool JavaThread::java_suspend(bool register_vthread_SR) {
>> 1185: // Suspending a vthread transition disabler can cause deadlocks.
>> 1186: // The HandshakeState::has_operation does not allow such suspends.
>
> So for a thread trying to self-suspend we don't use handshakes. We identify
> this case and call `do_owner_suspend()` directly, which would now hit the new
> assert added there. I think self-suspend within a `MountUnmountDisabler`
> scope is actually possible if some event is posted during the `interrupt`
> Java upcall. But maybe we should fix this case in a separate issue? (it's
> preexistent to this change)
Good check, thanks.
The `JvmtiJavaUpcallMark` hides the JVMTI events during the `interrupt` upcall:
JvmtiEnv::InterruptThread(jthread thread) {
. . .
if (java_lang_VirtualThread::is_instance(thread_obj)) {
// For virtual threads we have to call into Java to interrupt:
Handle obj(current_thread, thread_obj);
JvmtiJavaUpcallMark jjum(current_thread); // hide JVMTI events for Java
upcall <== !!!
JavaValue result(T_VOID);
JavaCalls::call_virtual(&result,
obj,
vmClasses::Thread_klass(),
vmSymbols::interrupt_method_name(),
vmSymbols::void_method_signature(),
current_thread);
> src/hotspot/share/runtime/suspendResumeManager.cpp line 136:
>
>> 134: while (is_suspended()) {
>> 135: log_trace(thread, suspend)("JavaThread:" INTPTR_FORMAT "
>> suspended", p2i(_target));
>> 136: assert(!_target->is_vthread_transition_disabler(), "attempt to
>> suspend a vthread transition disabler");
>
> We could check this once before the loop since only the current thread
> changes `_is_vthread_transition_disabler`.
Good suggestion, thanks! Fixed now.
> test/hotspot/jtreg/ProblemList.txt line 2:
>
>> 1: #
>> 2: # Copyright (c) 2016, 2026, Oracle and/or its affiliates. All rights
>> reserved.
>
> Not needed anymore.
Good catch, thanks. Fixed now.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/28740#discussion_r2711037099
PR Review Comment: https://git.openjdk.org/jdk/pull/28740#discussion_r2711038426
PR Review Comment: https://git.openjdk.org/jdk/pull/28740#discussion_r2711039636
