Semaphore
概述
共享锁，运行多个线程同时临界区
主要接口
public void acquire()
public void acquireUninterruptibly()
public boolean tryAcquire()
public boolean tryAcquire(long timeout, TimeUnit unit)
public void release()
共享锁，运行多个线程同时临界区
public void acquire()
public void acquireUninterruptibly()
public boolean tryAcquire()
public boolean tryAcquire(long timeout, TimeUnit unit)
public void release()
