Question about parallel gateway

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vladi

Hi,

i have tryed a very simple process with parallel gateway and two user task an each path:

<process id="concurency">
      <startEvent id="start" />
      <parallelGateway id="fork" />
      <userTask name="task_1" id="task_1" />
      <parallelGateway id="join" />
      <userTask name="task_2" id="task_2" />
      <userTask name="ready" id="ready" />
      <endEvent id="end" />
      
      <sequenceFlow sourceRef="start" targetRef="fork"/>
      <sequenceFlow sourceRef="fork" targetRef="task_1"/>
      <sequenceFlow sourceRef="fork" targetRef="task_2"/>
      <sequenceFlow sourceRef="task_1" targetRef="join"/>
      <sequenceFlow sourceRef="task_2" targetRef="join"/>
      <sequenceFlow sourceRef="join" targetRef="ready"/>
      <sequenceFlow sourceRef="ready" targetRef="end"/>
   </process>
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My point was, to see the behaviour of activity by asynchronous completing the user tasks. Each user task will be completed in own thread. After joining parallel pathes i am expecting to get the "ready" task but it get no task at all. Activiti use the database for synchronisation and in this case is seems doesnt to work.

Probably is misunderstood the manier in which i have to use the activiti for such tasks…

Any idea?

Thanks,
Vladimir

The junit is:

public class CuncurencyTest {

    @Rule
    public LogInitializer logSetup = new LogInitializer();
    @Rule
    public ProcessDeployer deployer = new ProcessDeployer();
    private ScheduledExecutorService executor;

    @Before
    public void setUp() throws Exception {
        this.executor = Executors.newScheduledThreadPool(10);
    }

    @After
    public void tearDown() throws Exception {
        this.executor.shutdownNow();
        this.executor.awaitTermination(10, TimeUnit.SECONDS);
    }

    @Test
    @ProcessDeclared
    public void testConcurency() throws Exception {
        ProcessInstance pi = this.deployer.getProcessService().startProcessInstanceByKey(
                "concurency");
        TaskQuery query = this.deployer.getTaskService().createTaskQuery().processInstance(
                pi.getId());

        List<Task> tasks = query.list();
        List<Callable<Object>> taskWorkers = new ArrayList();
        // complete user tasks asynchronously
        for (final Task task : tasks) {
            taskWorkers.add(new Callable() {
                @Override
                public Object call() throws Exception {
                    CuncurencyTest.this.deployer.getTaskService().complete(task.getId());

                    return null;
                }
            });
        }
        List<Future<Object>> futures = this.executor.invokeAll(taskWorkers);
        // Wait for process finished
        for (final Future<Object> future : futures) {
            future.get();
        }

        tasks = query.list();
        // I would expect here the usertask "ready"!
        assertEquals(1, tasks.size());
        assertEquals("ready", tasks.get(0).getName());
    }
}
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tombaeyens

process concurrency != multithreaded program execution

as you state correctly, activiti engine uses the db for synchronization.  a process is executed in transactional steps.  each step is calculated with a single thread.

because this question is  asked frequently, i wrote the answer in a faq: http://activiti.org/faq.html#WhatIsTheDifferenceBetweenProcessConcurrencyAndJavaConcurrency

let me know if this helps you further.