[CTJUG Forum] Re: Rogue Threads

Fri, 06 Oct 2006 06:39:42 -0700

I am using J2SE 5.0. Unfortunately, I don't know much about thread dumps. I'm busy reading something now called, "Understanding thread dumps", in the hope that it will shed some light on the problem.

Thread dump:

Full thread dump Java HotSpot(TM) Client VM (1.5.0_01-b08 mixed mode, sharing):

"DestroyJavaVM" prio=5 tid=0x000377a0 nid=0xca4 waiting on condition [0x00000000
..0x0007fae8]

"Thread-6" prio=5 tid=0x00ab7e78 nid=0x4bc runnable [0x00000000..0x0345f92c]

"Low Memory Detector" daemon prio=5 tid=0x00a6da78 nid=0x978 runnable [0x0000000
0..0x00000000]

"CompilerThread0" daemon prio=10 tid=0x00a6c6e0 nid=0xca8 waiting on condition [
0x00000000..0x02bcfa40]

"Signal Dispatcher" daemon prio=10 tid=0x00a6b8e8 nid=0xdcc waiting on condition
 [0x00000000..0x00000000]

"Finalizer" daemon prio=9 tid=0x00a68468 nid=0xf4c in Object.wait() [0x02b4f000.
.0x02b4fa68]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x22f51dd0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:116)
        - locked <0x22f51dd0> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:132)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java :159)

"Reference Handler" daemon prio=10 tid=0x00a46780 nid=0xc9c in Object.wait() [0x
02b0f000..0x02b0fae8]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x22f51e50> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:474)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
        - locked <0x22f51e50> (a java.lang.ref.Reference$Lock )

"VM Thread" prio=10 tid=0x00a39ad0 nid=0xe90 runnable

"VM Periodic Task Thread" prio=10 tid=0x00a6b828 nid=0x790 waiting on condition




On 10/6/06, Dr Heinz M. Kabutz <[EMAIL PROTECTED]> wrote:

Can you generate a thread dump?

What version of Java are you using?

Kind regards

Heinz
--
Dr Heinz M. Kabutz (PhD CompSci - University of Cape Town)
Sun Java Champion
Author of "The Java(tm) Specialists' Newsletter"
http://www.javaspecialists.co.za
Tel: +27 (83) 340-5633
Skype: kabutz



Fritz Meissner wrote:
> Hi,
>
> Can anyone tell me, what are common reasons why threads hang around
> and stop a program from exiting once all its work is done? I have the
> following situation:
>
> 1. Main thread calls a method, which starts up a thread to do stuff,
> and sets up a listener for certain events
>
> 2. The listener informs the main thread once its work is complete
>
> 3. Main thread sleeps until it hears from the listener that the new
> thread's work is finished
>
> 4. Main thread does some more work and then exits
>
> At this point I would expect the program to exit, but it doesn't.
>
> I should point out that I don't know the internals of what the new
> thread is doing, that code is hidden from me. This is all in the
> context of communicating using JSR-82 for Bluetooth; I am using the
> Avetana implementation. Their technical support guy to whom I've been
> talking says he is unable to duplicate the problem. I find this
> disturbing, because the starting point for my code was the sample code
> he's testing.
>
> And then another question: where do most people learn how to use
> threads properly? I've been "taught" threading - but all that involved
> was learning how to create threads; there was nothing about where to
> use what, how to avoid deadlock etc. Also nothing specific to Java -
> only C/C++ for an operating systems course.
>
> Fritz
>
>
> >


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