关闭时可使用如下代码
1 2 3 4 5 6 7 8 9 10 | public static void waitUntilTerminate( final ExecutorService executorService, final int timeout) { try { executorService.shutdown(); if (!executorService.awaitTermination(timeout, TimeUnit.SECONDS)) { //超时后直接关闭 executorService.shutdownNow(); } } catch (InterruptedException e) { //awaitTermination 出现中断异常也将触发关闭 executorService.shutdownNow(); } } |
但是实际使用中,可能会出现即使使用了shutdownNow方法,还是无法终止线程的问题,那是因为你的线程无法被中断
shutdownNow方法简单理解就是给在运行的线程发一个中断信号,如果你的线程忽略这个信号,那就无法停下来
举个例子来说明这个问题
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | public class ShutDownUtilsTest { private ExecutorService executorService; @Before public void init() { executorService = Executors.newFixedThreadPool( 1 ); } @Test public void shutDownOKTest() { ShutDownUtils.waitUntilTerminate(executorService, 1 ); CommonUtils.sleep( 1 ); //等待线程处理中断 Assert.assertTrue(executorService.isTerminated()); } @Test public void shutDownNowFailTest() { executorService.execute( this ::canNotStopThread); ShutDownUtils.waitUntilTerminate(executorService, 0 ); CommonUtils.sleep( 1 ); //等待线程处理中断 Assert.assertFalse(executorService.isTerminated()); } @Test public void shutDownNowOKTest() { executorService.execute( this ::stopThread); ShutDownUtils.waitUntilTerminate(executorService, 0 ); CommonUtils.sleep( 1 ); //等待线程处理中断 Assert.assertTrue(executorService.isTerminated()); } private void canNotStopThread() { for ( long i = 0 ; i < Long.MAX_VALUE; i++) { } } private void stopThread() { for ( long i = 0 ; i < Long.MAX_VALUE && !Thread.currentThread().isInterrupted(); i++) { } } } |
从上面的测试用例可以看到canNotStopThread无法被shutDownNow终止
然而stopThread可以被正常终止,因为通过Thread.currentThread().isInterrupted()在判断线程是否收到了中断信号
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持自学编程网。
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