How to run two instances of Apache ActiveMQ in one system? - apache

Question

I am using apache-activemq-5.11.1 which is the stable version runs on JDK 7 (Major version 51.0), I am using JDK 7 Update 80. I had error if I run the same on JDK 6.
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/apache/ac
tivemq/console/Main : Unsupported major.minor version 51.0
Coming to my problem I need to have two running instances of ActiveMQ in my system. I had followed the following steps to create two instance.
C:\>cd \apache-activemq-5.11.1
C:\apache-activemq-5.11.1>.\bin\activemq create instance1
C:\apache-activemq-5.11.1>.\bin\activemq create instance2
I had changed to different set of port numbers for instance2 as below,
<!--EDITED: apache-activemq-5.11.1\instance2\conf\activemq.xml-->
<transportConnectors>
<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
<transportConnector name="openwire" uri="tcp://0.0.0.0:61716?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:5772?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61713?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1983?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61714?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
</transportConnectors>
Now I am starting instance1 & instance2 as follows.....
C:\apache-activemq-5.11.1\instance1\bin>instance1 start
C:\apache-activemq-5.11.1\instance1\bin>instance2 start
Among these the second instance which I am trying to start gives the following kahadb lock problem.....
INFO | Refreshing org.apache.activemq.xbean.XBeanBrokerFactory$1#7209d9af: startup date [Thu May 07 16:16:23 IST 2015]; root of context hierarchy
INFO | PListStore:[C:\apache-activemq-5.11.1\data\localhost\tmp_storage] started
INFO | Using Persistence Adapter: KahaDBPersistenceAdapter[C:\apache-activemq-5.11.1\data\kahadb]
INFO | Database C:\apache-activemq-5.11.1\data\kahadb\lock is locked... waiting 10 seconds for the database to be unlocked. Reason: java.io.IOException: File 'C:\apache-activemq-5.11.1\data\kahadb\lock' could not be locked.
Please give a solution for this db lock issue.

Answer 1

Make a replica of your ActiveMQ like apache-activemq-x.xx.x to apache-activemq-x.xx.x_2
Change the ports of apache-activemq-x.xx.x_2\conf\activemq.xml. Make sure the port numbers that you are changing are not in clash.
<!--EDIT: apache-activemq-5.11.1_2\conf\activemq.xml-->
<transportConnectors>
<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
<transportConnector name="openwire" uri="tcp://0.0.0.0:61716?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:5772?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61713?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1983?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61714?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
</transportConnectors>
And along with port changes we have to correct jetty.xml http management console port as well.
<bean id="jettyPort" class="org.apache.activemq.web.WebConsolePort" init-method="start">
<!-- the default port number for the web console -->
<property name="host" value="0.0.0.0"/>
<property name="port" value="8162"/>
</bean>
In this way you can run two services of ActiveMQ in one system.

Answer 2

Running more instances created for ActiveMQ gives the Fail Over option.
In this way when one instance goes down for some reason. The other instance coming up automatically, since the first instance which locks the KahaDB is been released.
For this ports are not to be changed,- as we're configuring instances for Fail Over Mode.
C:\>cd \apache-activemq-5.11.1
C:\apache-activemq-5.11.1>.\bin\activemq create instance1
C:\apache-activemq-5.11.1>.\bin\activemq create instance2
Please start instances without changing any of the configuration. So when instance1 goes down for any reason, instance2 coming up.
C:\apache-activemq-5.11.1\instance1\bin>instance1 start
C:\apache-activemq-5.11.1\instance2\bin>instance2 start
I hope this must be the purpose of creating multiple instances under ActiveMQ. And more than this some more tweaky config. also available for Kahadb.

Answer 3

I did do the following instructions from:
Running Multiple ActiveMQ Instances on One Machine (Dzone)
It works fine for Mac (Not tested in Linux)
Note: the instances must be started through instanceNumber start (the console argument/parameter is not valid anymore).
I had the same problem about the kahadb locking only for Windows, it for ActiveMQ 5.13.3 and 5.14.5 versions
The same author from DZone wrote practically the same post in his blog
Running multiple ActiveMQ instances on one machine (Blog)
But there exists an important update.
You must open each instanceNumber.bat file for each instance from each bin directory and add these two lines:
set ACTIVEMQ_CONF="ACTIVEMQ_HOME/instanceNumber/conf"
set ACTIVEMQ_DATA="ACTIVEMQ_HOME/instanceNumber/data"
Where ACTIVEMQ_HOME represents the path location of your ActiveMQ and instanceNumber is the instance being edited such as: instanceA and instanceB

Answer 4

what is happening is you have changed the port numbers correctly but both the instances that you created use a same Database(in this case file system KahaDB) to store their messages,
So when one instance is up and running, it holds the lock for that database and other instance of activeMQ will be waiting to gain a lock of this DB.
Essentially this is becoming a master slave configuration .
look at this line in activeMQ.xml
<persistenceAdapter>
<kahaDB directory="${activemq.data}/kahadb"/>
</persistenceAdapter>
this will be pointing so same location for both instances.
what my solution is to copy entire folder apache-activemq-x.xx.x in different location change the port numbers for second instance and run them differently
by this you will have 2 instances of activeMQ running on same machine
hope this helps!
Good luck!

Answer 5

Although because of KahaDB restriction load balancing/fault tolerant configuration is restricted. We can use following kind of connection URL to utilize ActiveMQ load....
failover://(tcp://192.nnn.nn.nn:61616,tcp://192.nnn.nn.nn:61616)?randomize=false
randomize=true will made message shuffles between two AciveMQ in active mode, rather not by just fail-over of ActiveMQ......
Complete reference for this can be found under the following Apache Site link....
http://activemq.apache.org/failover-transport-reference.html
But Still high availability (i.e, cluster) configuration make things stable for your App although Apache must advance ActiveMQ High Availability, hence things can work smoother.
The present Apache ActiveMQ High Availability configuration available in the following link.
http://activemq.apache.org/clustering.html
Although KahaDB has file lock restriction, following tweaking/alternates ways of configuration can be done...
1)Shared File System Master Slave,- A shared file system such as a SAN
http://activemq.apache.org/shared-file-system-master-slave.html
2)JDBC Master Slave,- A Shared database
http://activemq.apache.org/jdbc-master-slave.html
3)Replicated LevelDB Store,- ZooKeeper Server
http://activemq.apache.org/replicated-leveldb-store.html
Over & above by having JCA connectors,- AS like JBoss, Weblogic, Websphere, Geronimo, Glassfish,- ActimeMQ patching as a kind of Resource Adapter can be done. And with Apache Camel (karaf), JBoss Fuse ESB kind of products HA & clustering of ActiveMQ can be done.