topic Re: Process variable content not properly passed to subprocess in Alfresco Archive

Process variable content not properly passed to subprocess

waldo — Tue, 12 Mar 2013 18:39:51 GMT

Dear community,I am stuck in a problem related to parameter passing and asynchronous subprocess calls and I hope that somebody can help me We are evaluating the use of Activiti (5.11) in a current project. We created some processes (which I cannot attach here) to get acquainted with Activiti.The p

Re: Process variable content not properly passed to subprocess

jbarrez — Wed, 13 Mar 2013 09:13:52 GMT

It's pretty hard to say with only this description of course, but

The stack was ~1700 items deep(!)

That for sure doesn't sound right. We do have a mechanism in place to avoid using the stack, but from what I read it might be broken here. How many steps does the process contain once you trigger it. Also keep in mind that the transaction will be open for the whole duration of all steps… some database (Oracle definitely) don't really like that.

Re: Process variable content not properly passed to subprocess

waldo — Wed, 13 Mar 2013 15:35:01 GMT

Unfortunately I'm not allowed to upload process definitions.

Some more info:

Basically all our activities are Java Service Tasks configured via delegate expressions, often times with start listeners attached:


    <serviceTask id="prepareAuthentication" name="prepareAuthentication" activiti:delegateExpression="${nd_PrepareAuthentication}"></serviceTask>
    
    <serviceTask id="setStateProcessing" name="setStateProcessing" activiti:delegateExpression="${nd_SetState}">
      <extensionElements>
        <activiti:executionListener event="start" class="com…..ServiceTaskListener">
          <activiti:field name="parameterName">
            <activiti:string>state</activiti:string>
          </activiti:field>
          <activiti:field name="parameter">
            <activiti:string>IN_PROGRESS</activiti:string>
          </activiti:field>
        </activiti:executionListener>
      </extensionElements>
    </serviceTask>

Numbers of service tasks: Incoming 13, Operate 61, Confirm 21, Syn 5
Processes generally contain loops, but in the case described no loop is executed more than once. All service tasks have exactly 1 outgoing connector into an Exclusive Gateway that dispatches on the result of the node. So roughly, there are as many Exclusive Gateways as there are service tasks (merge gateways not counted).

Call activities are defined thus:


    <callActivity id="ConfirmationRequestCreateAndPublish" name="ConfirmationRequestCreateAndPublish" activiti:async="true" calledElement="ConfirmationRequestCreateAndPublish">
      <extensionElements>
        <activiti:in source="PAYLOAD" target="PAYLOAD"></activiti:in>
        <activiti:smileysurprised:ut source="PAYLOAD" target="PAYLOAD"></activiti:smileysurprised:ut>
      </extensionElements>
    </callActivity>

Processes are started using


org.activiti.engine.RuntimeService.startProcessInstanceByKey(String, String, Map<String, Object>)

The message that is being sent from Incoming to Operate is realised via:


org.activiti.engine.RuntimeService.messageEventReceived(String, String, Map<String, Object>)

I'd like to attach the stack trace and Spring configuration, but the forum doesn't let me.

Any help would be highly appreciated, as the huge stack is really a show-stopper for us.

Re: Process variable content not properly passed to subprocess

jbarrez — Fri, 15 Mar 2013 08:53:49 GMT

Numbers of service tasks: Incoming 13, Operate 61, Confirm 21, Syn 5
Processes generally contain loops, but in the case described no loop is executed more than once. All service tasks have exactly 1 outgoing connector into an Exclusive Gateway that dispatches on the result of the node. So roughly, there are as many Exclusive Gateways as there are service tasks (merge gateways not counted).

Those numbers aren't really high … that should be no problem. Like I said, it was designed to cope with that, but I'm feeling something might went wrong there …

Any help would be highly appreciated, as the huge stack is really a show-stopper for us.

It's pretty hard to test without a test case. But I'll to to reproduce it myself locally.
Also, please do take in mind what I said about long transactions. That's why we added async continuations. I've seen plenty of DBA's going wild over keeping open transactions for a long time.

Re: Process variable content not properly passed to subprocess

waldo — Tue, 19 Mar 2013 07:04:12 GMT

I analysed Activiti stack behavior further and I am surprised by its stack consumption.

The simplest looping process consisting of a single synchronous service task increasing process variable N and one gateway checking N:

Start -> ServiceTask -> Gateway
Gateway [N >= 1000] -> End
Gateway [N < 1000] -> ServiceTask

representing a loop like this:


while (N < 1000) do
  N = N + 1 // ServiceTask

exits with a StackOverflowError after only 114 iterations. In every iteration the stack grows by roughly 80 elements!

Can you provide some details about the mechanism to avoid using the stack? How can I enable it, except by using async tasks, which would increase DB interaction quite drastically?

Re: Process variable content not properly passed to subprocess

jbarrez — Wed, 20 Mar 2013 09:50:54 GMT

Hmmm that sounds scary and buggy. When that piece was implemented (int he atomic operations) it wasn't the case, I checked it back then.

I'll look into it and see if there are workarounds/fixes that quickly can be made