如何使用长加法器执行

Question

你好，我有一个应用程序计算时间并根据它引发事件。我想让我的应用程序线程安全使用长加法器或任何合适的。

我下面的班级；

@Autowired
EventListenerConfiguration eventListenerConfiguration;
private volatile long lastReceivedMessage = System.currentTimeMillis();

public void consume(String message) Integer partition,
(Headers.OFFSET) Long offset, Acknowledgment ack) {

lastReceivedMessage = System.currentTimeMillis();
try {
seervice.processMessage(message, ack, null);
} catch (ParseException e) {
logger.error(e.getMessage());
}
}
@Scheduled(fixedDelayString = "${listenScheduled}", initialDelay = 100000)
private void distanceBetweenLastReceivedMessageAndCurrentTime() {
long currentTime = System.currentTimeMillis() - lastReceivedMessage;
if (currentTime >= EventListenerConfiguration .getTotalMilliSecondTimeForError()) {
EventUtil.publishEvent(THROW_ERROR_EVENT, EventSeverityStatus.ERROR, EventTypeStatus.CUSTOM, null);

} else (currentTime >= EventListenerConfiguration.getTotalMilliSecondTimeForWarn()) {
EventUtil.publishEvent(THROW_WARN_EVENT, EventSeverityStatus.WARN, EventTypeStatus.CUSTOM, null);
}
}

所以基本上如何转换我的代码而不需要对longAdder做太多更改，并执行currentTime-lastReceiveMessage

谢谢

Answer 1

晚上好。看来您的问题主要是lastReceivedMessage是由两个线程使用的受保护资源。无论运行consume方法的是什么，都会生成它，然后Spring Generated@scheduled线程会消耗它

添加volatile关键字不会阻止代码读取字段。它只会阻止代码缓存变量。(阅读volatilehttps://www.geeksforgeeks.org/volatile-keyword-in-java/)如果你想将@Scheduled块视为一个关键区域，并在lastRecievedMessage更新完成之前阻止它的更新，我建议如下：

private volatile long lastReceivedMessage = System.currentTimeMillis();
private Semaphore resourceLock = new Semaphore(1);
public void consume(String message) Integer partition,
(Headers.OFFSET) Long offset, Acknowledgment ack) {
resourceLock.acquireUninterruptibly();
try {
lastReceivedMessage = System.currentTimeMillis();
} finally {
resourceLock.release();
}
try {
seervice.processMessage(message, ack, null);
} catch (ParseException e) {
logger.error(e.getMessage());
}
}
@Scheduled(fixedDelayString = "${listenScheduled}", initialDelay = 100000)
private void distanceBetweenLastReceivedMessageAndCurrentTime() {
long currentTime = 0;
resourceLock.acquireUninterruptibly();
try {
currentTime = System.currentTimeMillis() - lastReceivedMessage;

if (currentTime >= EventListenerConfiguration .getTotalMilliSecondTimeForError()) {
EventUtil.publishEvent(THROW_ERROR_EVENT, EventSeverityStatus.ERROR, EventTypeStatus.CUSTOM, null);
} else (currentTime >= EventListenerConfiguration.getTotalMilliSecondTimeForWarn()) {
EventUtil.publishEvent(THROW_WARN_EVENT, EventSeverityStatus.WARN, EventTypeStatus.CUSTOM, null);
}
} finally {
resourceLock.release();
}
}