CODEWITHSUNDEEP
groovycamundacamunda-modeler
user2173353
user2173353

Reputation: 4680

Camunda 7 scripting - race conditions across process-instances while setting a variable

I am new to Camunda and I have a workflow with a sub-process that accesses parent variables.

Specifically, the parent does this in a script task (groovy code):

class Result {
    Boolean canProceed
    String errorMessage
}

Init();

def Init()
{
    def result = execution.hasVariable("result");
    if(result == false)
    {
        result = new Result();
//        execution.removeVariable("result");
        execution.setVariable("result", result);
    }
}

def setError(errorMessage)
{
    Init();
    def result = execution.getVariable("result");
    result.canProceed = false;
    result.errorMessage = errorMessage;
}

def setSuccess()
{
    Init();
    def result = execution.getVariable("result");
    result.canProceed = true;
    result.errorMessage = null;
}

And the sub-process calls the setSuccess() and setError("sth") functions.

The workflow does not contain any user tasks, so once I start a process instance, it executes and it gets done/destroyed, after I get the result variables back.

All is working fine when I call the workflow once at a time. But when I bombard it with parallel calls (each time creating a new process instance), then I get weird errors revolving around variables.

This is the C# code that calls the workflow in parallel:

var camunda = CamundaClient.Create("http://localhost:8080/engine-rest");
var pd = camunda.ProcessDefinitions.ByKey("name");

var actionNames = new string[] {
    ...
    ...
    ...
};

var repetition = 0;
var parallelOptions = new ParallelOptions { MaxDegreeOfParallelism = 10 };
await Parallel.ForEachAsync(actionNames, parallelOptions, async (actionName, ct) => {
    var result = await PerformAction(actionName: actionName);
});

async Task<Result> PerformAction(string actionName)
{
    var businessKey = $"temp-id:{Guid.NewGuid()}";

    var camundaResult = await pd.StartProcessInstance(new Camunda.Api.Client.ProcessDefinition.StartProcessInstance
    {
        BusinessKey = businessKey,
        Variables =
        {
            { "action", VariableValue.FromObject(new { name = actionName }) },
        },
        WithVariablesInReturn = true,
    });

    var processResultJson = camundaResult.Variables["result"]?.Value as string;
    var result = JsonSerializer.Deserialize<Result>(processResultJson, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
    return result;
}

When MaxDegreeOfParallelism is bigger than 1, I get all kinds of unexpected errors, like:

Any idea why this happens and what I can do to fix it?

Update:

Here are some stack traces (they were too long to post here): https://mega.nz/file/cR0VSLDA#W1f_a4Xxs6OI0hREfAc1SBwx0nzvDrQb3Jn1qPDoGpE

And here is the workflow file: https://mega.nz/file/NM1kDDxK#zsiqoi-7meHYLV4cYl7Qa9CAmQdtyFAW3aMf4cNAKA0

Upvotes: 0

Views: 181

Answers (0)

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