Re: RFR: 8232592: 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