Chapter 9. Detecting dead connections


To prevent AMQ Broker from running out of system resources, it is necessary to clean up inactive server-side resources, which often remain when clients do not stop gracefully. You can configure the duration that AMQ Broker waits before it cleans up inactive server-side resources.

9.1. Detecting dead connections

During garbage collection, the broker identifies client connections that were not properly shut down. The broker closes each connection and writes a message to the log. The log shows the exact line of code where a client session was instantiated, which enables you to identify and correct the error.

The following is an example of a message written to the log for a client connection that was not properly shut down.

[Finalizer] 20:14:43,244 WARNING [org.apache.activemq.artemis.core.client.impl.DelegatingSession]  I'm closing a JMS Conection you left open. Please make sure you close all connections explicitly before let
ting them go out of scope!
[Finalizer] 20:14:43,244 WARNING [org.apache.activemq.artemis.core.client.impl.DelegatingSession]  The session you didn't close was created here:
java.lang.Exception
   at org.apache.activemq.artemis.core.client.impl.DelegatingSession.<init>(DelegatingSession.java:83)
   at org.acme.yourproject.YourClass (YourClass.java:666) //
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Because the network connection between the client and the server can fail and then come back online, which allows a client to reconnect, AMQ Broker waits to clean up inactive server-side resources. This wait period is called a time to live (TTL). The default TTL for a network-based connection is 60000 milliseconds (1 minute). The default TTL on an in-VM connection is -1, which means the broker never times out the connection on the broker side.

The duration the broker waits before it cleans up inactive server-side resources is called a time to live (TTL). If you do not want any TTL value set by clients to apply, you can set a global TTL value on the broker, along with the interval at which the broker checks for TTL violations.

Procedure

  1. Edit <broker_instance_dir>/etc/broker.xml by adding the connection-ttl-override configuration element and providing a value for the time to live, as in the example below.

    <configuration>
     <core>
      ...
      <connection-ttl-override>30000</connection-ttl-override> //
      <connection-ttl-check-interval>1000</connection-ttl-check-interval> //
      ...
     </core>
    </configuration>
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    connection-ttl-override
    The global TTL for all connections. In the example, the TTL is set to 30000 milliseconds. The default value is -1, which allows clients to set their own TTL.
    connection-ttl-check-interval
    The interval between checks for dead connections. In the example, the interval is set to 1000 milliseconds. By default, the checks are done every 2000 milliseconds.
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