SYMPTOM
--------
When playing a number of Clips in a row, the system will eventually hang. Attached is some java code that shows the hang on our systems. The code is fairly straight forward:

   for ( ) {
           Start playing a clip
           wait for notify
    }
  Clip LineListener() {
    on STOP sleep a bit then close the clip
    on CLOSE notify
 }


CAUSE
------
Sometimes we will fail to receive the STOP event. Since the STOP event handler is responsible for closing the clip, we never get a chance to close it, and will end up waiting forever for the clip to close.

The longer I make the delay before the clip is closed, the less frequently this happens.

I've attached the java code, and the thread stack trace after a hang.

 
EXAMPLE
-------
import javax.sound.sampled.*;

public class AudioHangDemo {
    private Clip clip;
    private int count = 1;

    
    public void playClip() throws Exception {
// test.wav is any short (1 second) wave file
AudioInputStream audioInputStream =
            AudioSystem.getAudioInputStream(new java.io.File("test.wav"));
DataLine.Info info =
new DataLine.Info(Clip.class, audioInputStream.getFormat());
clip = (Clip) AudioSystem.getLine(info);

clip.addLineListener(new LineListener() {
public void update(LineEvent e) {
if (e.getType() == LineEvent.Type.STOP) {
System.out.println("STOP");
try {
Thread.sleep(50);
} catch (InterruptedException ie) {}
clip.close();
}
else if (e.getType() == LineEvent.Type.CLOSE) {
System.out.println("CLOSE");
synchronized(AudioHangDemo.this) {
AudioHangDemo.this.notify();
}
}
else if (e.getType() == LineEvent.Type.START) {
System.out.println("START");
}
}
});

clip.open(audioInputStream);
System.out.println(" ---------- start " + count + " --------");
clip.start();

System.out.println("waiting ... ");
synchronized(this) {
wait();
}
System.out.println("... done");
count++;
    }

    public static void main(String[] args) throws Exception {
AudioHangDemo ahd = new AudioHangDemo();

for (int i = 0; i < 1000; i++) {
ahd.playClip();
}

System.exit(0);
    }
}

 
STACK DUMP
---------------
Full thread dump Java HotSpot(TM) Client VM (1.4.0-rc-b91 mixed mode):

"Headspace mixer frame proc thread" daemon prio=1 tid=0x0x813c7b8 nid=0x1214 waiting on monitor [4c796000..4c79686c]
        at java.lang.Thread.sleep(Native Method)
        at com.sun.media.sound.MixerThread.runNative(Native Method)
        at com.sun.media.sound.MixerThread.run(MixerThread.java:314)

"Java Sound event dispatcher" prio=1 tid=0x0x813a210 nid=0x1213 waiting on monitor [4c6ae000..4c6ae86c]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x445f9d38> (a com.sun.media.sound.EventDispatcher)
        at java.lang.Object.wait(Object.java:426)
        at com.sun.media.sound.EventDispatcher.dispatchEvents(EventDispatcher.java:294)
        - locked <0x445f9d38> (a com.sun.media.sound.EventDispatcher)
        at com.sun.media.sound.EventDispatcher.run(EventDispatcher.java:345)
        at java.lang.Thread.run(Thread.java:536)

"Signal Dispatcher" daemon prio=1 tid=0x0x807bc50 nid=0x1211 waiting on monitor [0..0]

"Finalizer" daemon prio=1 tid=0x0x8074578 nid=0x120e waiting on monitor [4c2e2000..4c2e286c]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x445ea290> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:111)
        - locked <0x445ea290> (a java.lang.ref.ReferenceQueue$Lock)
        at java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:127)
        at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:159)

"Reference Handler" daemon prio=1 tid=0x0x8073930 nid=0x120d waiting on monitor [4c261000..4c26186c]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x445ea2f8> (a java.lang.ref.Reference$Lock)
        at java.lang.Object.wait(Object.java:426)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:113)
        - locked <0x445ea2f8> (a java.lang.ref.Reference$Lock)

"main" prio=1 tid=0x0x80515d8 nid=0x120a waiting on monitor [bfffd000..bfffd6fc]
        at java.lang.Object.wait(Native Method)
        - waiting on <0x445ea310> (a AudioHangDemo)
        at java.lang.Object.wait(Object.java:426)
        at AudioHangDemo.playClip(AudioHangDemo.java:40)
        - locked <0x445ea310> (a AudioHangDemo)
        at AudioHangDemo.main(AudioHangDemo.java:50)

"VM Thread" prio=1 tid=0x0x80707b0 nid=0x120c runnable

"VM Periodic Task Thread" prio=1 tid=0x0x807a778 nid=0x120f waiting on monitor
"Suspend Checker Thread" prio=1 tid=0x0x807b1d8 nid=0x1210 runnable

CONFIGURATION
-------------
java version "1.4.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-rc-b91)
Java HotSpot(TM) Client VM (build 1.4.0-rc-b91, mixed mode)

I am running on RedHat 7.2, no ALSA, emu10k sound.