RFR: 8320652: ThreadInfo.isInNative needs to be updated to say what executing native code means [v2]

[Bernd]

On Tue, 28 Nov 2023 14:36:19 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> btw for the following (system/native/runtime/embryotic) Reader thread tseems to be no java method marked "native" on the stack, what case is that?
>> 
>> 
>> "JDWP Event Helper Thread" #22 daemon prio=10 os_prio=0 cpu=0.00ms elapsed=65.02s tid=0x000001fc4f7e9970 nid=0x32e0 runnable  [0x0000000000000000]
>>    java.lang.Thread.State: RUNNABLE
>> 
>> "JDWP Command Reader" #23 daemon prio=10 os_prio=0 cpu=0.00ms elapsed=65.02s tid=0x000001fc4f7ea480 nid=0x69c4 runnable  [0x0000000000000000]
>>    java.lang.Thread.State: RUNNABLE
>> 
>> "Notification Thread" #24 daemon prio=9 os_prio=0 cpu=0.00ms elapsed=64.99s tid=0x000001fc4f7f12a0 nid=0x75f0 runnable  [0x0000000000000000]
>>    java.lang.Thread.State: RUNNABLE
>> 
>> jshell> mx.getThreadInfo(23)
>> $17 ==> "JDWP Command Reader" daemon prio=10 Id=23 RUNNABLE (in native)
>> 
>> funfact: its not in the list:
>> 
>> 
>> jshell> mx.getAllThreadIds()
>> $11 ==> long[8] { 1, 2, 3, 4, 5, 24, 25, 26 }
>
>> btw for the following (system/native/runtime/embryotic) Reader thread tseems to be no java method marked "native" on the stack, what case is that?
>> 
>> ```
>> "JDWP Event Helper Thread" #22 daemon prio=10 os_prio=0 cpu=0.00ms elapsed=65.02s tid=0x000001fc4f7e9970 nid=0x32e0 runnable  [0x0000000000000000]
>>    java.lang.Thread.State: RUNNABLE
>> 
>> "JDWP Command Reader" #23 daemon prio=10 os_prio=0 cpu=0.00ms elapsed=65.02s tid=0x000001fc4f7ea480 nid=0x69c4 runnable  [0x0000000000000000]
>>    java.lang.Thread.State: RUNNABLE
> 
> I think you are asking about JVMTI RunAgentThread. That's what the debugger agent uses to create its own threads. RunAgentThread is specified to hide the thread from Java APIs, it's nothing to do with this PR.

Well.. it has to do in so far, that those threads are not hidden - the ThreadInfo sees it and says "isNative". But ok if this is not expected, then indeed it does not need to be documented.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16791#discussion_r1408093987