JMX Connection refused

[Glenn Sheasby]

I'm incorporating cassandra-unit into our test suite, but I get the following error when I hit code that attempts to connect to cassandra via JMX. Should I be able to connect via JMX to the embedded cassandra server? Do I have to change some configuration to enable it?

The exception I get is:

java.io.IOException: Failed to retrieve RMIServer stub: javax.naming.ServiceUnavailableException [Root exception is java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: 

java.net.ConnectException: Connection refused]

When executing the following:

    private static final String URL_TEMPLATE = "service:jmx:rmi:///jndi/rmi://%s:%d/jmxrmi";

    private static JMXConnector getConnector(String jmxHost, int jmxPort) {

        String urlString = String.format(URL_TEMPLATE, jmxHost, jmxPort);

        try {

            JMXServiceURL url = new JMXServiceURL(urlString);

            return JMXConnectorFactory.connect(url, null);

       } ....

jmxHost is localhost, and jmxPort is 7199 (Cassandra's default), but running netstat doesn't show this port as open.

[Nate McCall]

JMX engine should be started, but it won't error out if it's not. Take
a look at:
https://github.com/apache/cassandra/blob/cassandra-2.0/src/java/org/apache/cassandra/service/CassandraDaemon.java#L147-L196

If any of those error or warn messages show up in the logs, you'll
need to set the corresponding system properties.

Also, this could be a race condition depending on when/how your code
is called in the lifecycle? Make sure it is after
https://github.com/jsevellec/cassandra-unit/blob/master/cassandra-unit/src/main/java/org/cassandraunit/utils/EmbeddedCassandraServerHelper.java#L95
as that will block until everything starts.

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[Glenn Sheasby]

Thanks for your response.

My CassandraDaemon looks different - it does not have the maybeInitJmx function.

I'm using cassandra-all-2.1.3 and cassandra-unit-2.1.3.1.

[Nate McCall]

Ok, some of that was moved around recently on 2.0, 2.1 and trunk.
Update to 2.1.5 (you should anyway, there have been a ton of fixes)
and you should see those messages.

Also, you may just need to set the following to get this to work with
your current:
com.sun.management.jmxremote.port=7199
com.sun.management.jmxremote.rmi.port=7199
com.sun.management.jmxremote.ssl=false
com.sun.management.jmxremote.authenticate=false

NOTE: this will allow JMX access to anything able to see that machine
on the network.

[Glenn Sheasby]

Thanks! Updating to cassandra-all 2.1.5 fixed it for me,

Since I'm using cassandra-unit, I don't have a cassandra-env.sh file to play with, but I added the following to my build.gradle:

Dependencies:

      testCompile ('org.cassandraunit:cassandra-unit:2.1.3.1') {

        exclude module: 'org.apache.cassandra:cassandra-all'

      }

      testCompile 'org.apache.cassandra:cassandra-all:2.1.5'

System properties (in task test):

      systemProperties['com.sun.management.jmxremote.port'] = 7199

      systemProperties['com.sun.management.jmxremote.rmi.port'] = 7199

      systemProperties['com.sun.management.jmxremote.ssl'] = false

      systemProperties['com.sun.management.jmxremote.authenticate'] = false

Note for others who have this problem: I also had to increate the MaxPermSize to 196m to get my entire test suite to run. If you get OOMs, you need to find and kill the test worker process (via jps) in order to free the port up.

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