public static StringBuilder doTest() {
    SynchSB thesb = allocate(SynchSB.class);
    {
      StringBuilder sb = allocate(StringBuilder.class);
      sb.value = new char[16];
      thesb.sb = sb;
    }
    for (int i = 0; i < 10000; i++) {
      synchronized (thesb) {
        StringBuilder sb = thesb.sb;
        String str = "abc";
        int len = 3; // str.value.length;
        int minimalCapacity = sb.count + len;
        if (minimalCapacity - sb.value.length > 0) {
          {
            int newCapacity = sb.value.length * 2 + 2;
            if (newCapacity - minimumCapacity < 0)
              newCapacity = minimumCapacity;
            if (newCapacity < 0) {
              if (minimumCapacity < 0) // overflow
                throw new OutOfMemoryError();
              newCapacity = Integer.MAX_VALUE;
            }
            {
              char[] original = sb.value;
              char[] copy = new char[newCapacity];
              System.arraycopy(original, 0, copy, 0,
                               Math.min(original.length, newCapacity));
              sb.value = copy;
            }
          }
        }
        System.arraycopy(str.value, 0, sb.value, sb.count, len);
        sb.count += len;
      }

      int sblen;
      synchronized (thesb) {
        sblen = thesb.sb.length;
      }
      synchronized (thesb) {
        StringBuilder sb = thesb.sb;
        System.arraycopy(sb.value, sblen, sb.value, 0, 0);
        sb.count = 0;
      }
    }
    return thesb.sb;
  }