Executor ThreadPool，垃圾回收

Question

我在一个do while循环中使用ThreadPool执行器作为守护进程。在每次迭代开始时，我创建newFixedThreadPool: executor = Executors.newFixedThreadPool(5)；

任务完成后，我会在下一次迭代开始之前调用shutdown，并为新的5个工作线程创建newFixedPool。

现在，在打印Log4J日志时。我使用%t来显示正在执行哪个线程池。我看到每一次迭代都会创建一个递增的新线程池。

在开始下一次迭代之前，请让我知道我需要调用executor=null吗？

是递增的线程池指示，线程池正在累积，可能会导致内存泄漏，因为它是一个守护进程，或者在后端线程池中将被垃圾收集，因为所有线程都已经完成，并且我们已经执行了shutdown。

 2014-06-26 16:26:11,548 [47    ] [INFO ][pool-1-thread-1] - Started processing new         payments for serverID: 5
2014-06-26 16:26:11,548 [47    ] [INFO ][pool-1-thread-2] - Started processing new payments for serverID: 6
2014-06-26 16:26:11,548 [47    ] [INFO ][pool-1-thread-3] - Started processing new payments for serverID: 7
2014-06-26 16:26:11,548 [47    ] [INFO ][pool-1-thread-4] - Started processing new payments for serverID: 8
2014-06-26 16:26:11,548 [47    ] [INFO ][pool-1-thread-5] - Started processing new payments for serverID: 9
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-2] - Completed processing new payments for serverID: 6
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-5] - Completed processing new payments for serverID: 9
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-2] - Time taken to Process new payments for serverId 6 : 12 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-5] - Time taken to Process new payments for serverId 9 : 12 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-3] - Completed processing new payments for serverID: 7
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-1] - Completed processing new payments for serverID: 5
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-3] - Time taken to Process new payments for serverId 7 : 12 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-1] - Time taken to Process new payments for serverId 5 : 12 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-4] - Completed processing new payments for serverID: 8
2014-06-26 16:26:24,129 [12628 ] [INFO ][pool-1-thread-4] - Time taken to Process new payments for serverId 8 : 12 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][main] - ShutDown complete
2014-06-26 16:26:24,129 [12628 ] [INFO ][main] - ProcessDeamon iteration finished in 0 Sec 
2014-06-26 16:26:24,129 [12628 ] [INFO ][main] - ProcessDeamon iteration started
2014-06-26 16:26:24,191 [12690 ] [INFO ][pool-2-thread-1] - Started processing new payments for serverID: 5
2014-06-26 16:26:24,191 [12690 ] [INFO ][pool-2-thread-2] - Started processing new payments for serverID: 6
2014-06-26 16:26:24,191 [12690 ] [INFO ][pool-2-thread-3] - Started processing new payments for serverID: 7
2014-06-26 16:26:24,191 [12690 ] [INFO ][pool-2-thread-4] - Started processing new payments for serverID: 8
2014-06-26 16:26:24,191 [12690 ] [INFO ][pool-2-thread-5] - Started processing new payments for serverID: 9

2014-06-26 16:26:34,443 [22942 ] [INFO ][pool-2-thread-2] - Completed processing new payments for serverID: 6
2014-06-26 16:26:34,443 [22942 ] [INFO ][pool-2-thread-2] - Time taken to Process new payments for serverId 6 : 10 Sec 
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-4] - Completed processing new payments for serverID: 8
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-3] - Completed processing new payments for serverID: 7
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-5] - Completed processing new payments for serverID: 9
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-4] - Time taken to Process new payments for serverId 8 : 10 Sec 
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-3] - Time taken to Process new payments for serverId 7 : 10 Sec 
2014-06-26 16:26:34,490 [22989 ] [INFO ][pool-2-thread-5] - Time taken to Process new payments for serverId 9 : 10 Sec 
2014-06-26 16:26:34,521 [23020 ] [INFO ][pool-2-thread-1] - Completed processing new payments for serverID: 5
2014-06-26 16:26:34,521 [23020 ] [INFO ][pool-2-thread-1] - Time taken to Process new payments for serverId 5 : 10 Sec 
2014-06-26 16:26:34,521 [23020 ] [INFO ][main] - ShutDown complete
2014-06-26 16:26:34,521 [23020 ] [INFO ][main] - ProcessDeamon iteration finished in 0 Sec 
2014-06-26 16:26:34,521 [23020 ] [INFO ][main] - ProcessDeamon iteration started

Answer 1

不要关闭你的线程池，而是重新使用它。这就是拥有线程池的全部意义:您将任务提交到这个池中，而不必关心线程管理。只需等待线程终止并将下一批任务提交到同一池中即可。