I am using simple MQTT client for publish and subscribe using Paho client java. I have limited resources of around 256MB or less of RAM (Linux machine with reduced capabilities). My QOS level is 0. My connection to mqtt broker is successful. I am able to send messages to broker successfully for an hour. My message rate is <= 1msg/s. After an hour my application just hangs. I read few posts on StackOverflow and other places and have setKeepAliveInterval as 120s and setTimeToWait as 1s(I have varied it from 2 min to 1s). I have tried async client, synchronous client with and without waitToComplete but it's reproducible in all cases. I have used both MemoryPersistence and File persistence - again reproducible in both cases. I have also tried topic.publish and client.publish - reproducible in both cases. Below is my code snippet:
@Override
public void connect() {
SSLContext sslContext = setSSLContext();
connOpt = new MqttConnectOptions();
connOpt.setSocketFactory(sslContext.getSocketFactory());
connOpt.setCleanSession(true);
connOpt.setUserName(userName);
connOpt.setPassword(password);
connOpt.setKeepAliveInterval(MQTT_KEEP_ALIVE_TIMEOUT_SECS);
// Connect to Broker
int retry = 1;
while (retry <= MQTT_CONNECT_RETRIES) {
try {
client = new MqttClient("ssl://" + mqtt.getMqttBrokerIp(), someId, memPersistence);
client.setCallback(callback);
client.connect(connOpt);
client.setTimeToWait(1000);
logger.info("msg='Connection to mqtt broker successful'");
return;
} catch (MqttException e) {
logger.warn(
"err='Connection to mqtt broker failed', retryNumber={}, errMessage={}, errStack={}",
retry, e.getMessage(), e.getStackTrace());
}
retry++;
}
logger.error("err='Connection to mqtt broker failed'");
}
@Override
public void publish(String topicPublish, String message) {
MqttMessage mqttMsg = new MqttMessage(message.getBytes());
mqttMsg.setQos(QOS);
mqttMsg.setRetained(false);
try {
client.publish(topicPublish, mqttMsg);
} catch (MqttPersistenceException e) {
logger.error("errMessage={}, errStack={}", e.getMessage(), e.getStackTrace());
} catch (MqttException e) {
logger.error("errMessage={}, errStack={}", e.getMessage(), e.getStackTrace());
}
/*
MqttMessage mqttMsg = new MqttMessage(message.getBytes());
MqttTopic topic = client.getTopic(topicPublish);
mqttMsg.setQos(QOS);
mqttMsg.setRetained(false);
try {
//memPersistence.clear();
MqttDeliveryToken token = topic.publish(mqttMsg);
token.waitForCompletion();
} catch (MqttPersistenceException e) {
logger.error("errMessage={}, errStack={}", e.getMessage(), e.getStackTrace());
} catch (MqttException e) {
logger.error("errMessage={}, errStack={}", e.getMessage(), e.getStackTrace());
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
logger.debug(" exception ");
}
*/
}
@Override
public void subscribe(String topicSubscribe) {
try {
client.subscribe(topicSubscribe, QOS);
} catch (MqttException e) {
logger.error("errMessage={}, errStack={}", e.getMessage(), e.getStackTrace());
}
}
My code runs for 1 hour or so and then always hangs before coming to deliveryComplete(). I have logs there to check which never get printed. My code hangs on following logs:
org.eclipse.paho.client.mqttv3.internal.Token notifyComplete FINE: 2384: >key=2061 response=null excep=null
I am using
maven { url 'https://repo.eclipse.org/content/repositories/paho-releases/' } in repository and compile 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.0.2' in my dependency in my build.gradle. I also tried
maven {
url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
}
in my repository. It did not help. Could anyone please suggest what IK may be doing wrong. I have gone through a lot of examples and post and after that I am posting here.
