RFR: 8332259: JvmtiTrace::safe_get_thread_name fails if current thread is in native state [v5]

[Serguei Spitsyn]

On Tue, 28 May 2024 22:29:28 GMT, Leonid Mesnik <lmesnik at openjdk.org> wrote:

>> The JvmtiTrace::safe_get_thread_name sometimes crashes when called while current thread is in native thread state.
>> 
>> It happens when thread_name is set for tracing from jvmti functions.
>> See:
>> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/prims/jvmtiEnter.xsl#L649 
>> 
>> The setup is called and the thread name is used in tracing before the thread transition. There is no good location where this method could be called from vm thread_state only. Some functions like raw monitor enter/exit never transition in vm state. So sometimes it is needed to call this function from native thread state.
>> 
>> The change should affect JVMTI trace mode only (-XX:TraceJVMTI). 
>> 
>> Verified by running jvmti/jdi/jdb tests with tracing enabled.
>
> Leonid Mesnik has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - fixed space.
>  - The result is updated.

This looks good, Posted one nit though.

src/hotspot/share/prims/jvmtiTrace.cpp line 284:

> 282:     JavaThreadState current_state = JavaThread::cast(Thread::current())->thread_state();
> 283:     if (current_state == _thread_in_native || current_state == _thread_blocked) {
> 284:       return "not readable";

Nit: I'd suggest to make it more detailed, something like like this:
 "<non-readable thread name>" or "<NON-READABLE-THREAD-NAME>"

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Marked as reviewed by sspitsyn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19275#pullrequestreview-2084079674
PR Review Comment: https://git.openjdk.org/jdk/pull/19275#discussion_r1618051643