[10] RFR: 8185796: jstack and clhsdb jstack should show lock objects

[Jini George]

Hi Yasumasa,

This is helpful, but looks like 'locked' is printed even when a thread 
is waiting for the monitor entry, or has unlocked a lock. For a simple 
test program, we would have:

"Thread-1" #11 prio=5 tid=0x00007f3938450000 nid=0x6be4 waiting for 
monitor entry [0x00007f3915010000]
    java.lang.Thread.State: BLOCKED (on object monitor)
    JavaThread state: _thread_blocked
  - ThreadLockTest.run() @bci=5, line=6 (Interpreted frame)
     - locked <0x000000072e96c490> (a java.lang.Class)
  - java.lang.Thread.run() @bci=11, line=844 (Interpreted frame)


"Thread-0" #10 prio=5 tid=0x00007f39383b7800 nid=0x6be3 waiting on 
condition [0x00007f3915111000]
    java.lang.Thread.State: TIMED_WAITING (sleeping)
    JavaThread state: _thread_blocked
  - java.lang.Thread.sleep(long) @bci=0 (Interpreted frame)
  - ThreadLockTest.run() @bci=8, line=6 (Interpreted frame)
     - locked <0x000000072e96c490> (a java.lang.Class)
  - java.lang.Thread.run() @bci=11, line=844 (Interpreted frame)

The corresponding output from the non SA jstack is as follows:

"Thread-1" #11 prio=5 os_prio=0 tid=0x00007f3938450000 nid=0x6be4 
waiting for monitor entry [0x00007f3915010000]
    java.lang.Thread.State: BLOCKED (on object monitor)
    JavaThread state: _thread_blocked
Thread: 0x00007f3938450000  [0x6be4] State: _at_safepoint 
_has_called_back 0 _at_poll_safepoint 0
    JavaThread state: _thread_blocked
         at ThreadLockTest.run(ThreadLockTest.java:6)
         -waiting to lock <0x000000072e96c490> (a java.lang.Class for 
ThreadLockTest)
         at java.lang.Thread.run(java.base/Thread.java:844)

    Locked ownable synchronizers:
         - None

"Thread-0" #10 prio=5 os_prio=0 tid=0x00007f39383b7800 nid=0x6be3 
waiting on condition [0x00007f3915111000]
    java.lang.Thread.State: TIMED_WAITING (sleeping)
    JavaThread state: _thread_blocked
Thread: 0x00007f39383b7800  [0x6be3] State: _at_safepoint 
_has_called_back 0 _at_poll_safepoint 0
    JavaThread state: _thread_blocked
         at java.lang.Thread.sleep(java.base/Native Method)
         at ThreadLockTest.run(ThreadLockTest.java:6)
         - locked <0x000000072e96c490> (a java.lang.Class for 
ThreadLockTest)
         at java.lang.Thread.run(java.base/Thread.java:844)

    Locked ownable synchronizers:
         - None

I think the various cases as seen in javaVFrame::print_lock_info_on() 
would have to be dealt with in SA. It would also be great if you could 
add a test case or modify an existing test case to test this along with 
the rest of your changes.

Thanks,
Jini (Not a (R)eviewer).


On 8/3/2017 8:13 PM, Yasumasa Suenaga wrote:
> Hi all,
>
> Thread dump shows lock objects, however jstack jhsdb and jstack in 
> CLHSDB are not show them.
> They are very useful for checking monitors. So jstack mode should show 
> them.
>
> I uploaded webrev. Could you review it?
>
>   http://cr.openjdk.java.net/~ysuenaga/JDK-8185796/webrev.00/
>
> This change prints locked stack looks like:
>
> * jhsdb jstack
> ----------------
> "main" #1 prio=5 tid=0x00007f1844018800 nid=0xe7f0 waiting on 
> condition [0x00007f184df31000]
>    java.lang.Thread.State: TIMED_WAITING (sleeping)
>    JavaThread state: _thread_blocked
>  - java.lang.Thread.sleep(long) @bci=0 (Interpreted frame)
>  - LongLock.main(java.lang.String[]) @bci=8, line=4 (Interpreted frame)
>     - locked <0x00000000dfc13b28> (a java.lang.Class)
> ----------------
>
> * jstack in CLHSDB
> ----------------
> "main" #1 prio=5 tid=0x00007f1844018800 nid=0xe7f0 waiting on 
> condition [0x00007f184df31000]
>    java.lang.Thread.State: TIMED_WAITING (sleeping)
>    JavaThread state: _thread_blocked
>  - java.lang.Thread.sleep(long) @bci=0 (Interpreted frame)
>  - LongLock.main(java.lang.String[]) @bci=8, line=4 (Interpreted frame)
>     - locked <0x00000000dfc13b28> (a java.lang.Class)
> ----------------
>
>
> I cannot access JPRT.
> So I need a sponsor.
>
>
> Thanks,
>
> Yasumasa
>
>

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