java - 优雅地关闭java应用程序(多线程)

Question

我正在尝试设置一个关闭 Hook 来处理 SIGTERM (kill -15)。它关闭了，但看起来并没有优雅地完成**处理**功能，因为它从未输出日志“线程已关闭”。

public class Runner {
    public static void main(String[] args) {
        Test test = new Test();
        Runtime.getRuntime().addShutdownHook(new Thread() {
                @Override
                public void run() {
                    try {
                        logger.warn("Shutting things down..."); // This works 
                        test.stop();
                    } catch (Exception ex) {
                        logger.error("Error shutting the app gracefully", ex);
                    }
                }
            });

        test.processing();
    }
}           


public class Test {
    private volatile boolean processingExit = false;
    public void stop() {
        processingExit = true;
    }

    public void processing() {
        while (!processingExit) {
            //do work here
            logger.info("doing work... keep printing..."); //This works until I send a kill -15 signal
        }
        // This log never works
        logger.info("Thread has been shutdown"); // This doesn't works 
    } 
}

Answer 1

问题在于，一旦关闭钩子(Hook)线程完成，进程就会停止，您需要让关闭钩子(Hook)线程等待主线程。

复制自 https://stackoverflow.com/a/2922031/1544715

来自the docs :

When the virtual machine begins its shutdown sequence it will start all registered shutdown hooks in some unspecified order and let them run concurrently. When all the hooks have finished it will then run all uninvoked finalizers if finalization-on-exit has been enabled. Finally, the virtual machine will halt.