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2024-03-14 08:00:00

如何正确地停止线程在Java?

我需要一个解决方案来正确地停止Java中的线程。

我有IndexProcessorclass，它实现了可运行接口:

public class IndexProcessor implements Runnable {

    private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);

    @Override
    public void run() {
        boolean run = true;
        while (run) {
            try {
                LOGGER.debug("Sleeping...");
                Thread.sleep((long) 15000);

                LOGGER.debug("Processing");
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
                run = false;
            }
        }

    }
}

我有ServletContextListener类启动和停止线程:

public class SearchEngineContextListener implements ServletContextListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

    private Thread thread = null;

    @Override
    public void contextInitialized(ServletContextEvent event) {
        thread = new Thread(new IndexProcessor());
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (thread != null) {
            thread.interrupt();
            LOGGER.debug("Thread successfully stopped.");
        }
    }
}

但是当我关闭tomcat时，我在IndexProcessor类中得到了异常:

2012-06-09 17:04:50,671 [Thread-3] ERROR  IndexProcessor Exception
java.lang.InterruptedException: sleep interrupted
    at java.lang.Thread.sleep(Native Method)
    at lt.ccl.searchengine.processor.IndexProcessor.run(IndexProcessor.java:22)
    at java.lang.Thread.run(Unknown Source)

我使用的是JDK 1.6。所以问题是:

我如何停止线程而不抛出任何异常?

附注:我不想使用.stop();方法，因为它已弃用。

当前回答

在IndexProcessor类中，您需要一种方法来设置一个标志，该标志通知线程它将需要终止，类似于您在类作用域中使用的变量run。

当您希望停止线程时，您可以设置这个标志并在线程上调用join()并等待它完成。

通过使用volatile变量或使用getter和setter方法来确保该标志是线程安全的，这些方法与用作标志的变量同步。

public class IndexProcessor implements Runnable {

    private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);
    private volatile boolean running = true;

    public void terminate() {
        running = false;
    }

    @Override
    public void run() {
        while (running) {
            try {
                LOGGER.debug("Sleeping...");
                Thread.sleep((long) 15000);

                LOGGER.debug("Processing");
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
                running = false;
            }
        }

    }
}

然后在SearchEngineContextListener中:

public class SearchEngineContextListener implements ServletContextListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

    private Thread thread = null;
    private IndexProcessor runnable = null;

    @Override
    public void contextInitialized(ServletContextEvent event) {
        runnable = new IndexProcessor();
        thread = new Thread(runnable);
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (thread != null) {
            runnable.terminate();
            thread.join();
            LOGGER.debug("Thread successfully stopped.");
        }
    }
}
2012-06-09 14:21:55

其他回答

对于同步线程，我更喜欢使用CountDownLatch，它可以帮助线程等待进程执行完成。在本例中，使用具有给定计数的CountDownLatch实例来设置工作者类。由于调用了countDown方法或达到了超时设置，await方法的调用将阻塞到当前计数为零。这种方法允许立即中断线程，而不需要等待指定的等待时间过去:

public class IndexProcessor implements Runnable {

    private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);

    private final CountDownLatch countdownlatch;
    public IndexProcessor(CountDownLatch countdownlatch) {
        this.countdownlatch = countdownlatch;
    }


    public void run() {
        try {
            while (!countdownlatch.await(15000, TimeUnit.MILLISECONDS)) {
                LOGGER.debug("Processing...");
            }
        } catch (InterruptedException e) {
            LOGGER.error("Exception", e);
            run = false;
        }

    }
}

当你想要完成另一个线程的执行时，在CountDownLatch上执行countDown，并将该线程加入主线程:

public class SearchEngineContextListener implements ServletContextListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

    private Thread thread = null;
    private IndexProcessor runnable = null;
    private CountDownLatch countdownLatch = null;

    @Override
    public void contextInitialized(ServletContextEvent event) {
        countdownLatch = new CountDownLatch(1);
        Thread thread = new Thread(new IndexProcessor(countdownLatch));
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (countdownLatch != null) 
        {
            countdownLatch.countDown();
        } 
        if (thread != null) {
            try {
                thread.join();
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
            }
            LOGGER.debug("Thread successfully stopped.");
        } 
    }
}
2012-06-09 14:52:01

在IndexProcessor类中，您需要一种方法来设置一个标志，该标志通知线程它将需要终止，类似于您在类作用域中使用的变量run。

当您希望停止线程时，您可以设置这个标志并在线程上调用join()并等待它完成。

通过使用volatile变量或使用getter和setter方法来确保该标志是线程安全的，这些方法与用作标志的变量同步。

public class IndexProcessor implements Runnable {

    private static final Logger LOGGER = LoggerFactory.getLogger(IndexProcessor.class);
    private volatile boolean running = true;

    public void terminate() {
        running = false;
    }

    @Override
    public void run() {
        while (running) {
            try {
                LOGGER.debug("Sleeping...");
                Thread.sleep((long) 15000);

                LOGGER.debug("Processing");
            } catch (InterruptedException e) {
                LOGGER.error("Exception", e);
                running = false;
            }
        }

    }
}

然后在SearchEngineContextListener中:

public class SearchEngineContextListener implements ServletContextListener {

    private static final Logger LOGGER = LoggerFactory.getLogger(SearchEngineContextListener.class);

    private Thread thread = null;
    private IndexProcessor runnable = null;

    @Override
    public void contextInitialized(ServletContextEvent event) {
        runnable = new IndexProcessor();
        thread = new Thread(runnable);
        LOGGER.debug("Starting thread: " + thread);
        thread.start();
        LOGGER.debug("Background process successfully started.");
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        LOGGER.debug("Stopping thread: " + thread);
        if (thread != null) {
            runnable.terminate();
            thread.join();
            LOGGER.debug("Thread successfully stopped.");
        }
    }
}
2012-06-09 14:21:55

我没有得到中断工作在Android，所以我用这个方法，工作完美:

boolean shouldCheckUpdates = true;

private void startupCheckForUpdatesEveryFewSeconds() {
    threadCheckChat = new Thread(new CheckUpdates());
    threadCheckChat.start();
}

private class CheckUpdates implements Runnable{
    public void run() {
        while (shouldCheckUpdates){
            System.out.println("Do your thing here");
        }
    }
}

 public void stop(){
        shouldCheckUpdates = false;
 }
2017-07-07 10:42:29

一些补充信息。 Java文档中都建议使用标志和中断。

https://docs.oracle.com/javase/8/docs/technotes/guides/concurrency/threadPrimitiveDeprecation.html

private volatile Thread blinker;

public void stop() {
    blinker = null;
}

public void run() {
    Thread thisThread = Thread.currentThread();
    while (blinker == thisThread) {
        try {
            Thread.sleep(interval);
        } catch (InterruptedException e){
        }
        repaint();
    }
}

对于需要长时间等待的线程(例如，等待输入)，使用thread .interrupt

public void stop() {
     Thread moribund = waiter;
      waiter = null;
      moribund.interrupt();
 }
2015-08-11 21:03:06

通常，线程在被中断时被终止。那么，为什么不使用本机布尔值呢?尝试isInterrupted ():

Thread t = new Thread(new Runnable(){
        @Override
        public void run() {
            while(!Thread.currentThread().isInterrupted()){
                // do stuff         
            }   
        }});
    t.start();

    // Sleep a second, and then interrupt
    try {
        Thread.sleep(1000);
    } catch (InterruptedException e) {}
    t.interrupt();

我如何杀死一个线程?不使用stop();

2018-11-27 10:31:53

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