RFR: 8192897: NPE occurs on clhsdb jstack

[Jini George]

Hi Yasumasa,

Thanks for this. Looks good.

Thanks,
Jini. (Not a Reviewer).

On 12/1/2017 7:26 PM, Yasumasa Suenaga wrote:
> Hi all,
> 
> I saw NPE when I run jstack on clhsdb as below:
> 
> ----------------
> hsdb> jstack
> Deadlock Detection:
> 
> No deadlocks found.
> 
> "NonBlockingInputStreamThread" #27 daemon prio=5 tid=0x00007f0924674000 
> nid=0xf429 in Object.wait() [0x00007f08cf6fd000]
>     java.lang.Thread.State: WAITING (on object monitor)
>     JavaThread state: _thread_blocked
>   - java.lang.Object.wait(long) @bci=0 (Compiled frame; information may 
> be imprecise)
>          - waiting on <no object reference available>
> Error occurred during stack walking:
> java.lang.NullPointerException
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.runtime.CompiledVFrame.getMonitors(CompiledVFrame.java:131) 
> 
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.runtime.JavaVFrame.printLockInfo(JavaVFrame.java:125) 
> 
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:114)
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor$26.doit(CommandProcessor.java:1073) 
> 
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:1964) 
> 
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:1934) 
> 
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.run(CommandProcessor.java:1814) 
> 
>          at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.run(CLHSDB.java:99)
>          at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.main(CLHSDB.java:40)
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runCLHSDB(SALauncher.java:191)
>          at 
> jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:439)
> ----------------
> 
> It is caused by CompiledVFrame#getScope() returns null.
> We should consider it at CompiledVFrame#getMonitors().
> 
> I uploaded a webrev. Could you review it?
> I checked this change with hotspot/jtreg/serviceability/sa on Linux x64.
> 
>    http://cr.openjdk.java.net/~ysuenaga/JDK-8192897/webrev.00/
> 
> We can reproduce this issue when we run the app with -Xcomp option.
> So I changed ClhsdbJstack.java to run with it.
> 
> 
> I cannot access mach5 and JPRT. So I need sponsor.
> 
> 
> Thanks,
> 
> Yasumasa
>