为何java里的Thread类的方法suspend()和resume()不推荐使用？

官方解释如下： http://download.oracle.com/javase/6/docs/technotes/guides/concurrency/threadPrimitiveDeprecation.html  
Why are Thread.suspend and Thread.resume deprecated?  
Thread.suspend is inherently deadlock-prone. If the target thread holds a lock on the monitor protecting a critical system resource when it is suspended, no thread can access this resource until the target thread is resumed. If the thread that would resume the target thread attempts to lock this monitor prior to calling resume, deadlock results. Such deadlocks typically manifest themselves as "frozen" processes. 

Thread.suspend方法是天生易发生死锁的。 
如果要suspend的目标线程对一个重要的系统资源持有锁，那么没任何线程可以使用这个资源直到要suspend的目标线程被resumed。 

如果一条线程将去resume目标线程之前尝试持有这个重要的系统资源再去resume目标线程，这两条线程就相互死锁了。 

suspend()和resume()
suspend()方法在线程挂起时，并不释放对象锁，因此可能会导致死锁。

替代实现：

class ThreadA implements Thread {
    private boolean theadSuspend;

    public void suspendThread() {
            threadSuspend = true;
    }

    public void resumeThread() {
            synchronized(this) {
                    threadSuspend = false;
                    notify();
            }
    }

    public void run() {
            while (true) {
                    synchronized (this) {
                            while (!threadSuspend)
                                    wait();
                    }

                    doSomething();
            }
    }
}