求解tomcat线程池源码

w1520138768

最近读tomcat源代码，其中线程池部分有一段完全看不懂，ThreadPoolExecutor.java源文件中的一个方法，不知道这个这个方法起什么作用，以及Context reload是什么意思，在什么情况下需要进行Context reload

1. public void contextStopping() {
   
2.         this.lastContextStoppedTime.set(System.currentTimeMillis());
   
3. 
   
4.         // save the current pool parameters to restore them later
   
5.         int savedCorePoolSize = this.getCorePoolSize();
   
6.         TaskQueue taskQueue =
   
7.                 getQueue() instanceof TaskQueue ? (TaskQueue) getQueue() : null;
   
8.         if (taskQueue != null) {
   
9.             // note by slaurent : quite oddly threadPoolExecutor.setCorePoolSize
   
10.             // checks that queue.remainingCapacity()==0. I did not understand
    
11.             // why, but to get the intended effect of waking up idle threads, I
    
12.             // temporarily fake this condition.
    
13.             taskQueue.setForcedRemainingCapacity(Integer.valueOf(0));
    
14.         }
    
15. 
    
16.         // setCorePoolSize(0) wakes idle threads
    
17.         this.setCorePoolSize(0);
    
18. 
    
19.         // wait a little so that idle threads wake and poll the queue again,
    
20.         // this time always with a timeout (queue.poll() instead of
    
21.         // queue.take())
    
22.         // even if we did not wait enough, TaskQueue.take() takes care of timing
    
23.         // out, so that we are sure that all threads of the pool are renewed in
    
24.         // a limited time, something like
    
25.         // (threadKeepAlive + longest request time)
    
26.         try {
    
27.             Thread.sleep(200L);
    
28.         } catch (InterruptedException e) {
    
29.             // yes, ignore
    
30.         }
    
31. 
    
32.         if (taskQueue != null) {
    
33.             // ok, restore the state of the queue and pool
    
34.             taskQueue.setForcedRemainingCapacity(null);
    
35.         }
    
36.         this.setCorePoolSize(savedCorePoolSize);
    
37.     }

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w1520138768

我自己顶一下