线程的状态

川长思鸟来 2022-02-15 13:47 265阅读 0赞

Thread源码里定义了6种状态，如下：

\* A thread state.  A thread can be in one of the following states: 
     \* <ul> 
     \* <li>\{@link \#NEW\} 
     \*     A thread that has not yet started is in this state. 
     \*     </li> 
     \* <li>\{@link \#RUNNABLE\} 
     \*     A thread executing in the Java virtual machine is in this state. 
     \*     </li> 
     \* <li>\{@link \#BLOCKED\} 
     \*     A thread that is blocked waiting for a monitor lock 
     \*     is in this state. 
     \*     </li> 
     \* <li>\{@link \#WAITING\} 
     \*     A thread that is waiting indefinitely for another thread to 
     \*     perform a particular action is in this state. 
     \*     </li> 
     \* <li>\{@link \#TIMED\_WAITING\} 
     \*     A thread that is waiting for another thread to perform an action 
     \*     for up to a specified waiting time is in this state. 
     \*     </li> 
     \* <li>\{@link \#TERMINATED\} 
     \*     A thread that has exited is in this state. 
     \*     </li> 
     \* </ul>

1 NEW:  
     一个线程被创建后，还没有调用start()方法，线程处于该状态。

2 RUNNABLE：  
     这个状态又分为2个小状态：READY和RUNNING,READY:处于NEW状态的线程，调用start()后，还没被cpu执行处于该状态。当被cpu执行时，就变为RUNNING状态了。一个RUNNING线程调用yield()会进入READY状态，在READY状态被CPU执行时进入了RUNNING状态。

3 BLOCKED  
     当线程等待锁，像synchronied锁和ReentrantLcok锁等，会处于这种状态。

4 WAITING  
     当线程等待其他线程的时候会处于这个状态，像RUNNING状态的线程调用Object.wait()或者LockSupport.park()或者otherThread.join()方法。和BLOCKED区别是BLOCKED等待的是锁，WAITING等待的是线程。

5 TIMED\_WAITING  
     他是一种等待时间已知的WAITING状态，在方法调用时候会带时间参数。

6 TERMINATED  
     线程执行结束处于该状态。