PHP IPC函数介绍信号量

以下是对信号量的处理函数，用于进程间通信(IPC)

sem_acquire — Acquire a semaphore
sem_get — Get a semaphore id
sem_release — Release a semaphore
sem_remove — Remove a semaphore

$key=ftok(__FILE__,'t');
$seg_id=sem_get($key); //获取一个信号id
sem_acquire($seg_id); //取的信号
//do something
sem_release($seg_id); //释放信号量
sem_remove($sem_id);  //删除一个信号