Java如何让线程主动让出 CPU

    /**
     * Causes the currently executing thread to sleep (temporarily cease
     * execution) for the specified number of milliseconds, subject to
     * the precision and accuracy of system timers and schedulers. The thread
     * does not lose ownership of any monitors.
     */
    public static native void sleep(long millis) throws InterruptedException;

    /**
     * A hint to the scheduler that the current thread is willing to yield
     * its current use of a processor. The scheduler is free to ignore this
     * hint.
     *
     * <p> Yield is a heuristic attempt to improve relative progression
     * between threads that would otherwise over-utilise a CPU. Its use
     * should be combined with detailed profiling and benchmarking to
     * ensure that it actually has the desired effect.
     *
     * <p> It is rarely appropriate to use this method. It may be useful
     * for debugging or testing purposes, where it may help to reproduce
     * bugs due to race conditions. It may also be useful when designing
     * concurrency control constructs such as the ones in the
     * {@link java.util.concurrent.locks} package.
     */
    public static native void yield();

    /**
     * Suspends this thread.
     * <p>
     * First, the <code>checkAccess</code> method of this thread is called
     * with no arguments. This may result in throwing a
     * <code>SecurityException </code>(in the current thread).
     * <p>
     * If the thread is alive, it is suspended and makes no further
     * progress unless and until it is resumed.
     *
     * @exception  SecurityException  if the current thread cannot modify
     *               this thread.
     * @see #checkAccess
     * @deprecated   This method has been deprecated, as it 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 <code>resume</code>, deadlock results.  Such
     *   deadlocks typically manifest themselves as "frozen" processes.
     *   For more information, see
     *   <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html" rel="external nofollow" >Why
     *   are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
     */
    @Deprecated
    public final void suspend() {
        checkAccess();
        suspend0();
    }

    @Deprecated
    public final void resume() {
        checkAccess();
        resume0();
    }