How can I set up so that these tasks can be executed simultaneously

I need node1 ~ node12 (or even more) to execute at the same time, how should I set it up, I can only make 8 tasks execute at the same time according to the following settings, why?
This is my setting:

process2.bpmn (19.7 KB)

    id: demo
    password: demo
    create: All tasks
    core-pool-size: 100
    max-pool-size: 300
    lock-time-in-millis: 7200000
    queue-capacity: 100
    max-jobs-per-acquisition: 100
    jdbc-batch-processing: false
  default-number-of-retries: 1

and this is my code:

public class NodeProcess
    private static final Logger logger = LoggerFactory.getLogger(NodeProcess.class);

    private final TaskService taskService;

    public NodeProcess(TaskService taskService)
        this.taskService = taskService;

    public void execute(DelegateExecution execution) throws Exception
        System.out.println(getTime() + "[thread:" + Thread.currentThread().getId() + "]"
                + " [node id:" + execution.getCurrentActivityId() + "]");

        Thread.sleep(1000 * 5);

    private static String getTime()
        SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return "[" + s.format(new Date()) + "] ";
public class Controller
    private RepositoryService repositoryService;
    private RuntimeService runtimeService;
    @RequestMapping(value = "/start", method = RequestMethod.GET)
    public String startBpmnFlow() throws Exception
        DeploymentBuilder deployment = repositoryService.createDeployment();
        BpmnModelInstance instance = Bpmn.readModelFromFile(new File("C:\\Users\\sherl\\Desktop\\process2.bpmn"));
        deployment.addModelInstance("C:\\Users\\sherl\\Desktop\\process2.bpmn", instance);
        Map<String, Object> initialVariables = new HashMap<>(1);
        runtimeService.startProcessInstanceByKey("process2", initialVariables);
        return "ok";

Why this camunda application can only parallel up to 8 ServiceTasks?
I really need help, thanks!

How have you determined this?

Also - please give more details about your Camunda setup and how it’s deployed, if it’s clustered etc.

Thank for your reply.@Niall
The above NodeProcess class can show my problem. When my task is executed, the console can see only the id of 8 tasks.
I use a single application.

You’re always going to be limited by the number of threads that can run in parallel on application that you’re running the engine on. So you can either increase the available threads and also increase the number of jobs that the engine can pick up and run or you can add another node (camunda instance) to your settup.