RFR: 8232592: <Unknown compiled code> is shown in jstack mixed mode

[Yasumasa Suenaga]

Hi Chris,

Thanks for your comment! I uploaded new webrev:

   http://cr.openjdk.java.net/~ysuenaga/JDK-8232592/webrev.01/


> So what does it mean if it is an NMethod but is not native and names != null. Should this ever happen? It seems odd that we don't print out the frame type in this case, and also don't call printUnknown().

I guess it might happen when call nmethod from JNI.
It would be handled as valid compiled code.

```
  166                       // print java frames, if any
  167                       if (names != null && names.length != 0) {
  168                          // print java frame(s)
  169                          for (int i = 0; i < names.length; i++) {
  170                              out.println(names[i]);
  171                          }
  172                       }
  ```


Thanks,

Yasumasa


On 2019/10/22 2:25, Chris Plummer wrote:
> Hi Yasumasa,
> 
> The call to getJavaNames() is not needed if the method is native. It should be moved into the else block:
> 
>                              if (cb.isNMethod()) {
>                                 if (cb.isNativeMethod()) {
> out.print(((CompiledMethod)cb).getMethod().externalNameAndSignature());
>                                    long diff = pc.minus(cb.codeBegin());
>                                    if (diff != 0L) {
>                                      out.print(" + 0x" + Long.toHexString(diff));
>                                    }
>                                    out.println(" (Native method)");
>                                 } else {
>                                     names = getJavaNames(th, f.localVariableBase());
>                                     if (names == null || names.length == 0) {
>                                         // just print compiled code, if can't determine method
> out.println("<Unknown compiled code>");
>                                     }
>                                 }
>                              } else if (cb.isBufferBlob()) {
> 
> So what does it mean if it is an NMethod but is not native and names != null. Should this ever happen? It seems odd that we don't print out the frame type in this case, and also don't call printUnknown().
> 
> thanks,
> 
> Chris
> 
> On 10/18/19 1:38 AM, Yasumasa Suenaga wrote:
>> Hi all,
>>
>> Please review this change.
>>
>>   JBS: https://bugs.openjdk.java.net/browse/JDK-8232592
>>   webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8232592/webrev.00/
>>
>> I run `jhsdb jstack --mixed` to JShellToolProvider process, then I saw <Unknown compiled code>
>> in the stack as below:
>>
>> ```
>> "process reaper" #13 daemon prio=10 tid=0x00007f959c328000 nid=0x1285 runnable [0x00007f9578025000]
>>    java.lang.Thread.State: RUNNABLE
>>    JavaThread state: _thread_in_native
>> 0x00007f95a27c5596 __waitpid + 0x56
>> 0x00007f958c601d79 <Unknown compiled code>
>> 0x00007f9585c5b4ac * java.lang.ProcessHandleImpl$1.run() bci:8 line:138 (Compiled frame)
>> ```
>>
>> 0x7f958c601d79 is native method. jstack mixed mode should handle it.
>> This patch passed all tests on submit repo (mach5-one-ysuenaga-JDK-8232592-20191018-0600-6011163).
>>
>>
>> Thanks,
>>
>> Yasumasa
>