When running ThreadGCBug test with JDK1.1.6 K build, with Symantec JIT turned on. The VM crashed right away. The test can never run more than 5 second. But the same test can run for weeks under interpreter. The following is the source code, compiler it and run with
java -Djava.compiler=symcjit ThreadGCBug

class T implements Runnable {
  static int nInstance = 0;
  synchronized public static int getNInstance() {return nInstance;}
  synchronized public static int incNInstance() {return nInstance++;}
  synchronized public static int decNInstance() {return nInstance--;}
  
  public void run2(String a[], String a1[], int sz, String sum) {
      int i;
      for(i=0;i<sz;i++)
        a1[i] = null;
      int s = 0;
      int inc;
      String b;
      for (i=0;i<sz;i++) {
        inc = a[i].length();
if (!a[i].regionMatches(0, sum, s, inc)) {
          System.out.print ("failed: i = " + i + "\n");
          System.out.print (" a[i] = " + a[i] + "\n");
          b = sum.substring(s, s+inc);
          System.out.print (" b = " + b + "\n");
int j;
for (j=0;j<inc;j++)
System.out.print ((int)(a[i].charAt(j)) + " " + (int)(b.charAt(j)) + "\n");
          break;
        }
        s += inc;
      }
  }

  public void run1(int pass) {
      int i;
      int res;
      int sz = 121;
      String[] a = new String [sz];
      String[] a1 = new String [sz];
      String sum = "1";

      a[0] = "1";
      for (i=1;i<sz;i++) {
        a[i] = a[i-1] + i;
        a1[i] = sum;
        sum = sum + a[i];
      }
      run2(a,a1,sz,sum);
      System.out.print (Thread.currentThread() + ": pass " + pass + "\n");
  }
  public void run() {
      try {
      int i;
      int n = (int)(10.0 * Math.random());
      for(i=0;i<n;i++)
        run1(i);
      decNInstance();
} catch (Throwable t) {
t.printStackTrace();
}
  }
}


class HT implements Runnable {

  public void run() {
      while(true) {
try {
          Thread.sleep(50);
        } catch (Exception e) {
e.printStackTrace();
}
      }
  }
}

class ThreadGCBug {
  public static void main1 (String[] args) {
    Thread ht = new Thread(new HT());
    ht.setPriority(7);
    ht.start();
    while (true) {
      T.incNInstance();
      Thread t = new Thread(new T());
      t.start();
      while (T.getNInstance() > 2) {
        try {Thread.sleep(100);}
catch (Exception e) {
e.printStackTrace();
}
      }
    }
  }
  public static void main (String[] args) {
    main1(args);
    int i;
    for (i=0;i<10000;i++) {
      int a[] = new int [100];
      a [9] = i;
    }
try{Thread.sleep(100000);} catch (Throwable e) {}
  }
}