Out of memory exception on Android while trying to reconnect

[zaur]

This is my code:

    private void setupMqttClient() {
        mqtt = new MQTT();
        mqtt.setKeepAlive((short) 20);
        mqtt.setCleanSession(true);
        mqtt.setConnectAttemptsMax(20000L);
        mqtt.setReconnectDelay(5L);
        mqtt.setReconnectDelayMax(30L);
        mqtt.setClientId("client_1");

        try {
            mqtt.setHost("192.168.0.140", 1883);
        } catch (URISyntaxException e) {
            e.printStackTrace();
        }

        BlockingConnection bc = mqtt.blockingConnection();
        try {
            bc.connect();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

I launch the app and client successfully connects.
Then I switch wifi off and on and wait until the client reconnects. After repeating this 2-3 times mqttclient starts opening and closing connections like crazy until the app crashes with OutOfMemoryError:

java.lang.OutOfMemoryError: Failed to allocate a 65548 byte allocation with 59328 free bytes and 57KB until OOM
    at org.fusesource.hawtdispatch.util.BufferPool.create(BufferPool.java:35)
    at org.fusesource.hawtdispatch.util.BufferPool.create(BufferPool.java:25)
    at org.fusesource.hawtdispatch.util.ThreadLocalPool.checkout(ThreadLocalPool.java:78)
    at org.fusesource.hawtdispatch.transport.AbstractProtocolCodec.allocateNextWriteBuffer(AbstractProtocolCodec.java:153)
    at org.fusesource.hawtdispatch.transport.AbstractProtocolCodec.write(AbstractProtocolCodec.java:137)
    at org.fusesource.hawtdispatch.transport.TcpTransport.offer(TcpTransport.java:649)
    at org.fusesource.mqtt.client.CallbackConnection$LoginHandler.onSuccess(CallbackConnection.java:388)
    at org.fusesource.mqtt.client.CallbackConnection$LoginHandler.onSuccess(CallbackConnection.java:319)
    at org.fusesource.mqtt.client.CallbackConnection$5.onTransportConnected(CallbackConnection.java:295)
    at org.fusesource.hawtdispatch.transport.TcpTransport.onConnected(TcpTransport.java:601)
    at org.fusesource.hawtdispatch.transport.TcpTransport$2$1$1.run(TcpTransport.java:490)
    at org.fusesource.hawtdispatch.internal.NioDispatchSource$3.run(NioDispatchSource.java:209)
    at org.fusesource.hawtdispatch.internal.SerialDispatchQueue.run(SerialDispatchQueue.java:100)
    at org.fusesource.hawtdispatch.internal.pool.SimpleThread.run(SimpleThread.java:77)

and here is what happens in mosquitto logs:

1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
1445865487: Client client_1 already connected, closing old connection.
1445865487: Client client_1 disconnected.
1445865487: New client connected from 192.168.0.130 as client_1 (c1, k20).
...................

[TheNitek]

Probably a duplicate of #48

[Rayman230510]

i merge the commit to my code,still OOM,how can i solve this problem? can you help me?

[ouyangzn]

Maybe you are trying to connect to the server repeated while it is already connected to server.
I had meet this problem, and i used a flag to sign the connection status, like this:

private void connect() {
    //AndroidUtils.checkNotMain();
    // 连接服务器
    if (isConnected()) {
      return;
    }
    mCallbackConnection = mMQTT.callbackConnection();
    mCallbackConnection.listener(new ExtendedListener() {
        @Override public void onConnected() {
          mConnected = true;
        }

        @Override public void onDisconnected() {
          mConnected = false;
        }
        ...
    }
}
private boolean isConnected() {
    return mConnected;
  }

Now it's ok, no OOM. But i got another problem ,somtimes it will crash:

Exception in thread "hawtdispatch-DEFAULT-2" java.lang.NullPointerException
    at org.fusesource.mqtt.client.CallbackConnection$7.run(CallbackConnection.java:450)
    ......

public void onSessionEstablished(Transport transport) {
    if(mqtt.getKeepAlive()>0) {
            heartBeatMonitor = new HeartBeatMonitor();
            heartBeatMonitor.setWriteInterval((mqtt.getKeepAlive() * 1000) / 2);
            heartBeatMonitor.setTransport(this.transport);
            heartBeatMonitor.suspendRead(); // to match the suspended state of the transport.
            heartBeatMonitor.setOnKeepAlive(new Task() {
                @Override
                public void run() {
                    // Don't care if the offer is rejected, just means we have data outbound.
                    if(!disconnected && pingedAt==0) {
                        MQTTFrame encoded = new PINGREQ().encode();
                        //   -------------this.transport == null----------------
                        if(CallbackConnection.this.transport.offer(encoded)) {
            ............
}

[Rayman230510]

The commit #48 & #51，This line has been changed , like this:
if(CallbackConnection.this.transport != null && CallbackConnection.this.transport.offer(encoded))
and delete this: //handleSessionFailure(new ProtocolException("Ping TimeOut").fillInStackTrace());
and i have tried this ,there is no some bad effects, i hope this will help for your NullPointException.

THKS.

[ouyangzn]

@zhlmgithub
I don't know why delete this line:
java handleSessionFailure(new ProtocolException("Ping TimeOut").fillInStackTrace());
It seems there will not reconnect to server when heartbeat timeout if delete this line.

void handleSessionFailure(Throwable error) {
    // Socket failure, should we try to reconnect?
    if (!disconnected && (mqtt.reconnectAttemptsMax < 0
        || reconnects < mqtt.reconnectAttemptsMax)) {

      mqtt.tracer.debug("Reconnecting transport");
      // Cleanup the previous transport.
      if (heartBeatMonitor != null) {
        heartBeatMonitor.stop();
        heartBeatMonitor = null;
      }
      final Transport t = transport;
      transport = null;

      if (t != null) {
        t.stop(new Task() {
          @Override public void run() {
            listener.onDisconnected();
            reconnect();
          }
        });
      } else {
        reconnect();
      }
    } else {
      // nope.
      handleFatalFailure(error);
    }
  }