How could I track unknown Thread/Runnable?

I'm developing Java MIDI application.

And I have stuck with debugging of exception, which dispatching at the end of song. As I'm expecting: the application is playing and each time I'm checking the sequence tick position to represent it in application playback line, like as player.

So I want to know how could I get the source or the point where this Thread start running?

Below is an exception output:

Exception in thread "Thread-23" java.lang.IllegalState开发者_JAVA技巧Exception: Sequencer is not open
    at org.tritonus.share.midi.TSequencer.checkOpen(TSequencer.java:296)
    at org.tritonus.share.midi.TSequencer.stop(TSequencer.java:256)
    at org.tritonus.midi.device.java.JavaSequencer.run(JavaSequencer.java:291)
    at java.lang.Thread.run(Unknown Source)

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You could install a security manager which allows absolutely everything, but logs out when it's asked for permission to start a thread.

Or, you could provide a replacement Thread implementation and put it ahead of the one in rt.jar by using the bootclasspath options, and have this replacement Thread log its name and stacktrace in its constructor.

---

org/tritonus/midi/device/java/JavaSequencer.java has the following code:

protected void openImpl()
    {
            ...
            m_thread = new Thread(this);
            ...
            m_thread.start();
    }

So that's one place to look for (but that answers only the specific case, not the general question how to find out where a thread is started in general).

There are also other places in the same class where this.start() is called: in setSequence(..) and setTickPosition(..). There could be calls to start() outside the class however.