RFR: 8337331: crash: pinned virtual thread will lead to jvm crash when running with the javaagent option [v3]

[Serguei Spitsyn]

On Mon, 29 Jul 2024 11:30:08 GMT, Jiawei Tang <jwtang at openjdk.org> wrote:

>> I add the testcase which can reproduce the crash. I hope that I could get some advise if the codes need changing.
>
> Jiawei Tang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   changes according to reviewers' advice

src/hotspot/share/prims/jvmtiExport.cpp line 970:

> 968:     if (_thread->is_in_any_VTMS_transition()) {
> 969:       return; // no events should be posted if thread is in any VTMS transition
> 970:     }

This is not right place to fix it.

This would be better:

@@ -1091,8 +1091,8 @@ bool JvmtiExport::post_class_file_load_hook(Symbol* h_name,
   if (JvmtiEnv::get_phase() < JVMTI_PHASE_PRIMORDIAL) {
     return false;
   }
-  if (JavaThread::current()->is_in_tmp_VTMS_transition()) {
-    return false; // skip CFLH events in tmp VTMS transition
+  if (thread->is_in_any_VTMS_transition()) {
+    return; // no events should be posted if thread is in any VTMS transition
   }
 
   JvmtiClassFileLoadHookPoster poster(h_name, class_loader,


Also, there is a check in the constructor `JvmtiClassFileLoadHookPoster()`:

    if (_thread->is_in_any_VTMS_transition()) {
      return; // no events should be posted if thread is in any VTMS transition
    }

It is better to replace it with assert. With the right check in the `JvmtiExport::post_class_file_load_hook()` we should never call this constructor and `poster.post()`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20373#discussion_r1696039799