protected void finalize() {
done.reset();
for (int i = 0; i < threads.length; i++) {
threads[i].interrupt();
done.workerBegin();
// threads[i].destroy();
}
done.waitDone();
}
// 分配线程
public synchronized void assign(Runnable r) {
done.workerBegin();
assignments.add(r);
notify();
}
