Job executor into homogeneous environment

Camunda 7 Topics Discussion & Questions
1

Hii guys, I need to understand How the Job Executor work into Homogeneous environment (https://docs.camunda.org/manual/7.6/user-guide/process-engine/the-job-executor/#cluster-setups)

My Environment:

  • Node A with Process Application X
  • Node B with Process Application X

Process Application contains a cycle triggered by timer. During the cycle I insert a Service Task Y.

Test Scenario:

  • Start an instance of Application X calling Node A
  • Start an instance of Application X calling Node B

during the tests, I note that the Service Task runs always on Node B

Could you please help me to understand?

Regards,
Luca

2

Hi Luca,

could you please clarify what you mean by “cycle” and “During the cycle I insert a Service Task Y.”.

A Job Executer in a homogenous cluster aquires jobs from database and locks them on database. So it is ensured that job is not executed on both nodes.
Which Job Executor of Node A and B aquires the job is not guaranteed.

If you need this, JobExecutor must be deploymentAware and Process Application X on Node A and B must have different names for their deployments.

Bets regards,

Markus

3

I attached my BPMN diagram. Service Task is Service Task Y. Each 2 minutes the Service Task will be started.

endless cycle.png710×402 7.13 KB

4

Hi Luca,

In a homogenous cluster there is no guarantee on which Node Service Task is executed.
I think it is hazard that it is always executed on node B.

Could you post the configuration of your job executor pls.

Best regards,

Markus

5 
<subsystem xmlns="urn:org.camunda.bpm.jboss:1.1">
        <process-engines>
            <process-engine name="default" default="true">
                <datasource>java:jboss/datasources/ProcessEngine</datasource>
                <history-level>full</history-level>
                <properties>
                    <property name="jobExecutorAcquisitionName">
                        default
                    </property>
                    <property name="isAutoSchemaUpdate">
                        true
                    </property>
                    <property name="authorizationEnabled">
                        false
                    </property>
                    <property name="jobExecutorDeploymentAware">
                        true
                    </property>
                </properties>
                <plugins>
                    <plugin>
                        <class>org.camunda.bpm.application.impl.event.ProcessApplicationEventListenerPlugin</class>
                    </plugin>
                    <plugin>
                        <class>org.camunda.spin.plugin.impl.SpinProcessEnginePlugin</class>
                    </plugin>
                    <plugin>
                        <class>org.camunda.connect.plugin.impl.ConnectProcessEnginePlugin</class>
                    </plugin>
                </plugins>
            </process-engine>
        </process-engines>
        <job-executor>
            <core-threads>3</core-threads>
            <max-threads>5</max-threads>
            <queue-length>10</queue-length>
            <job-acquisitions>
                <job-acquisition name="default">
                    <properties>
                        <property name="lockTimeInMillis">
                            300000
                        </property>
                        <property name="waitTimeInMillis">
                            5000
                        </property>
                        <property name="maxJobsPerAcquisition">
                            3
                        </property>
                    </properties>
                </job-acquisition>
            </job-acquisitions>
        </job-executor>
    </subsystem>
6

I would like this behavior:

My Environment:

  • Node A with Process Application X
  • Node B with Process Application X

Test Scenario:

  1. Start an instance of Application X calling Node A (instance ABC)
  2. The Service Task executed on Node A
  3. Start an instance of Application X calling Node B (instance XYZ)
  4. The Service Task executed on Node B (two instances: ABC, XYZ)
  5. Kill the Node B
  6. The Service Task will never be performed more. Why?

Could you please help to understand the behaviour?

Regards,
Luca

7

Please try this:

  <property name="jobExecutorDeploymentAware">
                        false
  </property>

instead of true.

If I understand you correct you want to achieve that Service Task is executed one Node A or Node B and that it is not important that it is a specific node.
So if you set jobExecutorDeploymentAware to false the jobExecutor will not make a difference if it is allowed top execute the Service Task or not.

Could you test this pls.

Best regards,

Markus

8