Native deadlock in PrintStream?

Question

I've been working on a multi-threaded application where multiple threads are sending output to System.out. I've found what appears to be a native call that deadlocks on occassion, and I'm wondering if I might be doing something wrong.
I'm running JDK 1.4.1, Windows XP Pro
I doubt that it matters, but I'm running inside the Eclipse development environment.
Here is the stack trace of the deadlock:
Thread [WaitThread3] (Suspended)
     java.io.FileOutputStream.writeBytes(byte[], int, int) line: not available [native method] [local variables unavailable]
     java.io.FileOutputStream.write(byte[], int, int) line: 257
     java.io.BufferedOutputStream.flushBuffer() line: 69
     java.io.BufferedOutputStream.flush() line: 127
     java.io.PrintStream.write(byte[], int, int) line: 260
     sun.nio.cs.StreamEncoder$CharsetSE.writeBytes() line: 334
     sun.nio.cs.StreamEncoder$CharsetSE.implFlushBuffer() line: 402
     sun.nio.cs.StreamEncoder$CharsetSE(sun.nio.cs.StreamEncoder).flushBuffer() line: 113
     java.io.OutputStreamWriter.flushBuffer() line: 169
     java.io.PrintStream.write(java.lang.String) line: 305
     java.io.PrintStream.print(java.lang.String) line: 448
     java.io.PrintStream.println(java.lang.String) line: 585
     TestMultiThreadSystemOut$WaitThread.run() line: 37
and here is some sample code to reproduce:
import java.util.Random;
* @author Kevin Day
* A class used to reproduce native deadlock issue in System.out
public class TestMultiThreadSystemOut {
     static Random rnd = new Random();
     private class WaitThread extends Thread{
          int minDelay = 1000;
          int maxDelay = 1000;
          int count = 0;     
          public WaitThread(String name, int minDelay, int maxDelay){
               super(name);     
               this.minDelay = minDelay;
               this.maxDelay = maxDelay;
               if (this.minDelay >= this.maxDelay){
                    this.minDelay = this.maxDelay - 1;
          * @see java.lang.Runnable#run()
          public void run() {
               try {
                    while (true){
                         count++;
                         long sleepFor = minDelay + rnd.nextInt(maxDelay - minDelay);
                         System.out.println(this.getName() + " : Call number " + count + " - sleeping for " + sleepFor);
                         Thread.sleep(sleepFor);
               } catch (InterruptedException e) {
     * Constructor for TestMultiThreadSystemOut.
     public TestMultiThreadSystemOut() {
          super();
     public void doTest(){
          //Create some threads that all print to System.out at random intervals
          Thread t = null;
          int numThreads = 5;
          for (int i = 0; i < numThreads; i++){
               t = new WaitThread("WaitThread" + i, 150, 500);
               t.start();
          // Let those threads run, and send my own message to System.out every 3 seconds
          try {
               while (true){
                    Thread.sleep(3000);
                    System.out.println("Main thread output");     
          } catch (InterruptedException e) {
     public static void main(String[] args) {
          TestMultiThreadSystemOut a = new TestMultiThreadSystemOut();
          a.doTest();

Answer 1

Solved the problem. It turns out that the Eclipse IDE was the problem - once I upgraded to M5, the deadlock went away.
- K
I've been working on a multi-threaded application
where multiple threads are sending output to
System.out. I've found what appears to be a native
call that deadlocks on occassion, and I'm wondering if
I might be doing something wrong.
I'm running JDK 1.4.1, Windows XP Pro
I doubt that it matters, but I'm running inside the
Eclipse development environment.