ActiveMQ 5.x

- How does ActiveMQ work ?

  ActiveMQ sends message between client application - producers
  Consumers sẽ là recived and process massage. The ActiveMQ broker router each message throught one of two type of destinations:

        - a queue : point-to-point
        - topic : publish/subscribe

- Memory and Storage
   A. Memory
     ActiveMQ uses memory to store messages awaiting dispatch to consumers.
     ActiveMQ also writes messages to disk, in either a message store (where persistent messages go), or a temp store (where non-persistent messages go when the broker runs out of memory to store them).

    Có 2 cách thức gửi message : persistent và non-persistent

           non-persistent : Each non-persistent message is stored in memory as it arrives. When the available memory is full, all messages in memory are moved to the temp store on the disk. Nếu service stop thì mất tất cả dữ liệu

      ( Lưu trong memory , nếu memory không còn thì sẽ thực hiện ghi xuống temporary file.)

           persistent: Each persistent message is also stored in memory as it arrives, and is also written to the message store on disk (KahaDB). If no more memory is available, incoming persistent messages are written directly into the message store. Sẽ không mất dữ liệu khi bi stop

JMS is the communication standard that ActiveMQ uses to send and receive messages. ActiveMQ is a JMS provider, which means that it implements the functionality specified in the JMS API. Client applications—producers and consumers—use the JMS API to send and receive messages.

Mặc đinh thì ActiveMQ statup script tell Java to create a heap with maximum size là 1GB (-Xmx).

Gía trị -Xmx là giá trị memory JMS . để cấu hình memory limit thì có 2 cách

c1. Cấu hình sử dụng memoryUsage

...]
    <systemUsage>
        <systemUsage>
            <memoryUsage>
                <memoryUsage limit="1 gb" />
            </memoryUsage>
        </systemUsage>
    </systemUsage>
[...]
</broker>

c2. Cấu hình sử dụng percentOfJvmHeap

[...]
    <systemUsage>
        <systemUsage>
            <memoryUsage>
                <memoryUsage percentOfJvmHeap="60" />
            </memoryUsage>
        </systemUsage>
    </systemUsage>
[...]
</broker>

Gía trị  cursorMemoryHighWaterMark tức là khi đến % của giá trị memoryLimit thì dữ liệu sẽ tự động đẩy xuống disk

memoryLimit	n/a	The memory limit (in bytes) of the destination’s cursor. This memory limit is subordinate to the system level memory limit, as specified by the <systemUsage>/<memoryUsage> attribute. There is no default for this value; it simply acts as a child to the overall broker memory until the broker memory is exhausted. Note: when this limit is specified the destination’s cursorMemoryHighWaterMark will be applied against it and not the <systemUsage>/><memoryUsage> memory limit.
cursorMemoryHighWaterMark	70	The percentage (%) threshold applied either to the <systemUsage>/<memoryUsage> or the destination’s memoryLimit (when defined) which when exceeded will cause the destination’s cursor to either block or write to disk.

tham khảo:

http://activemq.apache.org/per-destination-policies

B. Storage

You can specify the amount of storage to be used for persistent messages in the activemq.xml file’s storeUsage element, as in the example below:

<systemUsage>
    <systemUsage>
        <storeUsage>
            <storeUsage limit="100 mb"/>
        </storeUsage>
    </systemUsage>
</systemUsage>

Storage for non-persistent messages is specified separately. Non-persistent messages are written to storage only after available memory is exhausted. You can specify the amount of storage to be used for non-persistent messages in the activemq.xml file’s tempUsage element, which defaults to 50 GB. You can configure this as a percentage of available disk space (percentLimit) or as a number of bytes (as shown below):

<systemUsage>
    <systemUsage>
        <tempUsage>
            <tempUsage limit="100 mb"/>
        </tempUsage>
    </systemUsage>
</systemUsage>

- ActiveMQ message store :

     - KahaDB message store

     - AMQ message store

     - JDBC message store

     - Memory message store 

     

KahaDB is a file based persistence database that is local to the message broker that is using it. It has been optimized for fast persistence. It is the the default storage mechanism since ActiveMQ 5.4. KahaDB uses less file descriptors and provides faster recovery than its predecessor, the AMQ Message Store.

Configuration


To use KahaDB as the broker’s persistence adapter configure ActiveMQ as follows (example):

 <broker brokerName="broker">
    <persistenceAdapter>
      <kahaDB directory="activemq-data" journalMaxFileLength="32mb"/>
    </persistenceAdapter>
 </broker>

- Cấu truc directory của KahaDB trên local server:

       - db.data:This file contains the persistent BTree indexes to the messages held in the message
data logs.
       - db.redo:  This is the redo file, used for recovering the BTree indexes if the KahaDB message store starts after a hard stop
       - db.log : This exists only if archiving is enabled. The archive is used to store data logs that are no longer needed by KahaDB, making it possible to replay messages from the archived data logs at a later point. If archiving isn’t enabled (the default), data logs that are no longer in use are deleted
from the file system.

  

- Cấu hình monitor cho activeMQ sử dụng Hawtio
  1. Insert Hawtio
         -  wget -c https://oss.sonatype.org/content/repositories/public/io/hawt/hawtio-default/2.3.0/hawtio-default-2.3.0.war
      - unzip hawtio-default-2.3.0.war -d hawtio
      - mv hawtio <PATH_TO_ACTIVEMQ_INSTALLATION>/webapps

Then, edit the env file in the bin directory of your ActiveMQ installation. Add the following line at the end of the file:

ACTIVEMQ_OPTS="$ACTIVEMQ_OPTS -Dhawtio.realm=activemq -Dhawtio.role=admins -Dhawtio.rolePrincipalClasses=org.apache.activemq.jaas.GroupPrincipal"

Hawtio, edit jetty.xml in the conf/ subdirectory under your ActiveMQ installation directory to add Hawtio as a web component of your ActiveMQ installation. Find the <ref bean="rewriteHandler"/> tag and add this block immediately after it:

<bean class="org.eclipse.jetty.webapp.WebAppContext"> <property name="contextPath" value="/hawtio" /> <property name="resourceBase" value="${activemq.home}/webapps/hawtio" /> <property name="logUrlOnStart" value="true" /> </bean>

Hawtio installation with a secure password, edit the conf/users.properties file. Locate the line that reads:

admin=admin

Edit it by specifying your desired password:

admin=<MY_NEW_PASSWORD>

Restart ActiveMQ and browse to http://<YOUR_ACTIVEMQ_HOST_IP>:8161/hawtio. You can now log in with the username admin and the password <MY_NEW_PASSWORD>.

activemq-performance-tuning

http://www.mastertheboss.com/old-stuff/apache-activemq/activemq-performance-tuning

Using ActiveMQ – “Master/Slave” configuration with failover protocol

https://www.javacodegeeks.com/2014/04/using-activemq-masterslave-configuration-with-failover-protocol.html

https://examples.javacodegeeks.com/enterprise-java/jms/apache-activemq-failover-example/