topic Re: multiInstance won't run task in parallel. in Alfresco Archive

multiInstance won't run task in parallel.

clstokes — Thu, 10 Oct 2013 03:12:06 GMT

I'm trying to execute a task on a collection in parallel, however no combination of settings seems to change the behavior from running sequentially.Here's my test case in Groovy:<blockcode>package testsimport org.activiti.engine.ProcessEngineimport org.activiti.engine.ProcessEngineConfiguratio

Re: multiInstance won't run task in parallel.

clstokes — Thu, 10 Oct 2013 03:14:01 GMT

This is with Activiti 5.13.

Re: multiInstance won't run task in parallel.

clstokes — Wed, 16 Oct 2013 14:48:42 GMT

Created ticket ACT-1814. http://jira.codehaus.org/browse/ACT-1814

Re: multiInstance won't run task in parallel.

jbarrez — Mon, 21 Oct 2013 10:47:36 GMT

See http://activiti.org/faq.html#WhatIsTheDifferenceBetweenProcessConcurrencyAndJavaConcurrency

Activiti does not use real concurrency, as it would make using activiti tricky regarding transactions and more specifically syncing when different threads would end. Hence, we decided to opt for the simple approach which so far has saved many people from headaches.

Re: multiInstance won't run task in parallel.

clstokes — Thu, 24 Oct 2013 23:07:16 GMT

I'm sorry for being dense, but what's the practical implication of this?

Does this mean that if I ran two JVM processes that my serviceTask in parallel across those processes?
Or does it mean that if I ran two JVM processes that my serviceTask would distributed across those processes but still sequentially?

Is this the same case when doing a parallel gateway?

Thanks for the help.

Re: multiInstance won't run task in parallel.

trademak — Fri, 25 Oct 2013 10:02:17 GMT

The parallel gateway and multiinstance constructs are able to run multiple user tasks in parallel for example. But for service and script tasks they are basically executed serial still. Async can change this behavior if you also set exclusive to false (the default is true). Then the job executor will just execute all jobs available and not serially. So give it a try to set async to true and exclusive to false.

Best regards,

Re: multiInstance won't run task in parallel.

clstokes — Mon, 28 Oct 2013 20:56:44 GMT

I tried setting async to true and exclusive to false on both the scriptTask and multiInstanceLoopCharacteristics and got the same result. What am I doing wrong?

<code>
<?xml version="1.0" encoding="UTF-8" ?>
<definitions id="definitions"
             targetNamespace="http://activiti.org/bpmn20"
             xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xmlns:activiti="http://activiti.org/bpmn">

<process id="ParallelServiceTest">

    <startEvent id="start"/>

    <sequenceFlow id="_1" sourceRef="start" targetRef="printValue"/>

    <scriptTask id="printValue"
                name="Execute script"
                scriptFormat="groovy"
                activiti:async="true"
                activiti:exclusive="false">
      <multiInstanceLoopCharacteristics
          isSequential="false"
          activiti:collection="${values}"
          activiti:elementVariable="value"
          activiti:async="true"
          activiti:exclusive="false">
      </multiInstanceLoopCharacteristics>
      <script>
        System.out.println(execution.getVariable("value"))
        Thread.sleep(3000)
      </script>
    </scriptTask>

    <sequenceFlow id="_end" sourceRef="printValue" targetRef="end"/>

    <endEvent id="end"/>

</process>

</definitions>
</code>

<code>
13:53:56.580 [Test worker] INFO o.s.b.f.xml.XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [activiti.cfg.xml]
13:53:58.600 [Test worker] INFO o.a.engine.impl.db.DbSqlSession - performing create on engine with resource org/activiti/db/create/activiti.h2.create.engine.sql
13:53:58.660 [Test worker] INFO o.a.engine.impl.db.DbSqlSession - performing create on history with resource org/activiti/db/create/activiti.h2.create.history.sql
13:53:58.678 [Test worker] INFO o.a.engine.impl.db.DbSqlSession - performing create on identity with resource org/activiti/db/create/activiti.h2.create.identity.sql
13:53:58.686 [Test worker] INFO o.a.engine.impl.ProcessEngineImpl - ProcessEngine default created
13:53:58.687 [Test worker] INFO o.a.e.impl.jobexecutor.JobExecutor - Starting up the JobExecutor[org.activiti.engine.impl.jobexecutor.DefaultJobExecutor].
13:53:58.690 [Thread-6] INFO o.a.e.i.j.AcquireJobsRunnable - JobExecutor[org.activiti.engine.impl.jobexecutor.DefaultJobExecutor] starting to acquire jobs
13:53:58.751 [Test worker] INFO o.a.e.i.bpmn.deployer.BpmnDeployer - Processing resource activiti-processes/ParallelServiceTest.bpmn20.xml
13:53:58.930 [Test worker] INFO o.a.e.i.bpmn.deployer.BpmnDeployer - Processing resource activiti-processes/GridEnvironment.bpmn20.xml

Gradle test > ParallelJobTest.testResult STANDARD_OUT
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
</code>

Re: multiInstance won't run task in parallel.

trademak — Thu, 31 Oct 2013 09:48:53 GMT

I don't think this test is sufficient to come to conclusions. The jobs are inserted in the logical order and executed immediately, so it still does make sense that you get this result. Maybe you can implement some Thread.sleep with an random number of miliseconds?

Best regards,

Re: multiInstance won't run task in parallel.

clstokes — Fri, 01 Nov 2013 01:08:53 GMT

Added a random wait of 0-20 seconds…

<code>
<?xml version="1.0" encoding="UTF-8" ?>
<definitions id="definitions"
             targetNamespace="http://activiti.org/bpmn20"
             xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xmlns:activiti="http://activiti.org/bpmn">

<process id="ParallelServiceTest">

    <startEvent id="start"/>

    <sequenceFlow id="_1" sourceRef="start" targetRef="printValue"/>

    <scriptTask id="printValue"
                name="Execute script"
                scriptFormat="groovy"
                activiti:async="true"
                activiti:exclusive="false">
      <multiInstanceLoopCharacteristics
          isSequential="false"
          activiti:collection="${values}"
          activiti:elementVariable="value"
          activiti:async="true"
          activiti:exclusive="false">
      </multiInstanceLoopCharacteristics>
      <script>
        def random = new Random()
        def wait = random.nextInt(1000)*20
        System.out.println(execution.getVariable("value") + " - waiting " + wait + "ms")
        Thread.sleep(wait)
      </script>
    </scriptTask>

    <sequenceFlow id="_end" sourceRef="printValue" targetRef="end"/>

    <endEvent id="end"/>

</process>
</definitions>
</code>

<code>
17:59:10.337 [main] INFO o.s.b.f.xml.XmlBeanDefinitionReader - Loading XML bean definitions from class path resource [activiti.cfg.xml]
17:59:12.460 [main] INFO o.a.engine.impl.db.DbSqlSession - performing create on engine with resource org/activiti/db/create/activiti.h2.create.engine.sql
17:59:12.521 [main] INFO o.a.engine.impl.db.DbSqlSession - performing create on history with resource org/activiti/db/create/activiti.h2.create.history.sql
17:59:12.536 [main] INFO o.a.engine.impl.db.DbSqlSession - performing create on identity with resource org/activiti/db/create/activiti.h2.create.identity.sql
17:59:12.542 [main] INFO o.a.engine.impl.ProcessEngineImpl - ProcessEngine default created
17:59:12.544 [main] INFO o.a.e.impl.jobexecutor.JobExecutor - Starting up the JobExecutor[org.activiti.engine.impl.jobexecutor.DefaultJobExecutor].
17:59:12.546 [Thread-3] INFO o.a.e.i.j.AcquireJobsRunnable - JobExecutor[org.activiti.engine.impl.jobexecutor.DefaultJobExecutor] starting to acquire jobs
17:59:12.589 [main] INFO o.a.e.i.bpmn.deployer.BpmnDeployer - Processing resource activiti-processes/ParallelServiceTest.bpmn20.xml
17:59:12.765 [main] INFO o.a.e.i.bpmn.deployer.BpmnDeployer - Processing resource activiti-processes/GridEnvironment.bpmn20.xml
17:59:12.875 [main] INFO o.a.e.i.bpmn.deployer.BpmnDeployer - Processing resource activiti-processes/ResultAndExceptionTest.bpmn20.xml

0 - waiting 3180ms
1 - waiting 16960ms
2 - waiting 540ms
3 - waiting 700ms
4 - waiting 4100ms
5 - waiting 15320ms
6 - waiting 14640ms
7 - waiting 800ms
8 - waiting 10980ms
9 - waiting 320ms
</code>

Re: multiInstance won't run task in parallel.

trademak — Tue, 05 Nov 2013 13:35:54 GMT

You're right, multi instance doesn't work together with async. Is there a specific use case you would like to implement using a similar construct? Could you explain that use case? It could be that Activiti isn't suited for this use case.

Best regards,

Re: multiInstance won't run task in parallel.

trademak — Wed, 13 Nov 2013 21:21:01 GMT

Okay, so there's a restriction of 120 seconds on the thread execution and the multi-instance task can take 5+ minutes. And what you would like to see is that the multi-instance is performed in parallel with multiple threads so that it might only take 30 seconds or so?

Best regards,

Re: multiInstance won't run task in parallel.

trademak — Fri, 15 Nov 2013 15:09:44 GMT

Right, this is not supported currently in the job executor. But it could be an improvement for the next Activiti release to add support for multi threaded (managed by the application server) job executors.

Best regards,

Re: multiInstance won't run task in parallel.

trademak — Wed, 20 Nov 2013 15:29:54 GMT

Ok cool, looking forward to your findings.

isSequential is only meaningful when you use a user task or an other wait state task. For a service task you are right that there's no difference.

Best regards,

Re: multiInstance won't run task in parallel.

clstokes — Fri, 22 Nov 2013 17:44:21 GMT

The user guide should be updated to list this limitation (user task or an other wait state task) of multiInstanceLoopCharacteristics/isSequential. I wasted a lot of time on this.

Re: multiInstance won't run task in parallel.

trademak — Tue, 26 Nov 2013 09:10:53 GMT

Yes, the userguide could be improved there.

Best regards,

Re: multiInstance won't run task in parallel.

oliver35 — Thu, 09 Oct 2014 16:18:02 GMT

Hi,

I have excatly the same requirement about having a real paralellism for multiinstance tasks execution . (and also just as clstokes … lost some time trying to troubleshoot !!).

It would be nice to have this feature soon in Activiti.

My use case: I use activiti to to push configuration changes to network devices.

Re: multiInstance won't run task in parallel.

trademak — Fri, 10 Oct 2014 09:04:13 GMT

Ok, sorry to hear that you lost time on this. Yes it's a very valid feature. You can create a JIRA issue or upvote an existing issue. For our priority list we primarily look at the community demand, so if more people need this feature it will get a higher priority.

Best regards,

Re: multiInstance won't run task in parallel.

oliver35 — Fri, 10 Oct 2014 15:56:30 GMT

Please could anyone (with a JIARA access) create an entry for this topic?

Re: multiInstance won't run task in parallel.

oliver35 — Mon, 13 Oct 2014 09:51:14 GMT

ACT-2126 - multiinstance serviceTasks need real parallelism
has been created