聊聊artemis的connectionTtlCheckInterval

public class ConfigurationImpl implements Configuration, Serializable {

   private long connectionTtlCheckInterval = ActiveMQDefaultConfiguration.getDefaultConnectionTtlCheckInterval();

   //......

   @Override
   public long getConnectionTtlCheckInterval() {
      return connectionTtlCheckInterval;
   }

   @Override
   public ConfigurationImpl setConnectionTtlCheckInterval(long connectionTtlCheckInterval) {
      this.connectionTtlCheckInterval = connectionTtlCheckInterval;
      return this;
   }

   //......
}

public class RemotingServiceImpl implements RemotingService, ServerConnectionLifeCycleListener {

   //......

   private FailureCheckAndFlushThread failureCheckAndFlushThread;

   private long connectionTtlCheckInterval;

   //......

   public synchronized void start() throws Exception {
      if (started) {
         return;
      }

      logger.tracef("Starting remoting service %s", this);

      paused = false;

      // The remoting service maintains it's own thread pool for handling remoting traffic
      // If OIO each connection will have it's own thread
      // If NIO these are capped at nio-remoting-threads which defaults to num cores * 3
      // This needs to be a different thread pool to the main thread pool especially for OIO where we may need
      // to support many hundreds of connections, but the main thread pool must be kept small for better performance

      ThreadFactory tFactory = AccessController.doPrivileged(new PrivilegedAction<ThreadFactory>() {
         @Override
         public ThreadFactory run() {
            return new ActiveMQThreadFactory("ActiveMQ-remoting-threads-" + server.toString() +
                                                "-" +
                                                System.identityHashCode(this), false, Thread.currentThread().getContextClassLoader());
         }
      });

      threadPool = Executors.newCachedThreadPool(tFactory);

      for (TransportConfiguration info : acceptorsConfig) {
         createAcceptor(info);
      }

      /**
       * Don't start the acceptors here.  Only start the acceptors at the every end of the start-up process to avoid
       * race conditions. See {@link #startAcceptors()}.
       */

      // This thread checks connections that need to be closed, and also flushes confirmations
      failureCheckAndFlushThread = new FailureCheckAndFlushThread(connectionTtlCheckInterval);

      failureCheckAndFlushThread.start();

      started = true;
   }

   //......

}

   private final class FailureCheckAndFlushThread extends Thread {

      private final long pauseInterval;

      private volatile boolean closed;
      private final CountDownLatch latch = new CountDownLatch(1);

      FailureCheckAndFlushThread(final long pauseInterval) {
         super("activemq-failure-check-thread");

         this.pauseInterval = pauseInterval;
      }

      public void close(final boolean criticalError) {
         closed = true;

         latch.countDown();

         if (!criticalError) {
            try {
               join();
            } catch (InterruptedException e) {
               throw new ActiveMQInterruptedException(e);
            }
         }
      }

      @Override
      public void run() {
         while (!closed) {
            try {
               long now = System.currentTimeMillis();

               Set<Pair<Object, Long>> toRemove = new HashSet<>();

               for (ConnectionEntry entry : connections.values()) {
                  final RemotingConnection conn = entry.connection;

                  boolean flush = true;

                  if (entry.ttl != -1) {
                     if (!conn.checkDataReceived()) {
                        if (now >= entry.lastCheck + entry.ttl) {
                           toRemove.add(new Pair<>(conn.getID(), entry.ttl));

                           flush = false;
                        }
                     } else {
                        entry.lastCheck = now;
                     }
                  }

                  if (flush) {
                     flushExecutor.execute(new Runnable() {
                        @Override
                        public void run() {
                           try {
                              // this is using a different thread
                              // as if anything wrong happens on flush
                              // failure detection could be affected
                              conn.scheduledFlush();
                           } catch (Throwable e) {
                              ActiveMQServerLogger.LOGGER.failedToFlushOutstandingDataFromTheConnection(e);
                           }

                        }
                     });
                  }
               }

               for (final Pair<Object, Long> pair : toRemove) {
                  final RemotingConnection conn = getConnection(pair.getA());
                  if (conn != null) {
                     // In certain cases (replicationManager for instance) calling fail could take some time
                     // We can't pause the FailureCheckAndFlushThread as that would lead other clients to fail for
                     // missing pings
                     flushExecutor.execute(new Runnable() {
                        @Override
                        public void run() {
                           conn.fail(ActiveMQMessageBundle.BUNDLE.clientExited(conn.getRemoteAddress(), pair.getB()));
                        }
                     });
                     removeConnection(pair.getA());
                  }
               }

               if (latch.await(pauseInterval, TimeUnit.MILLISECONDS))
                  return;
            } catch (Throwable e) {
               ActiveMQServerLogger.LOGGER.errorOnFailureCheck(e);
            }
         }
      }
   }