The Process Engine supports the concept of the parallel execution of steps, also known as step locking. You implement step locking on a per-step basis, by selecting the Allow parallel execution check box in the Implementation tab of the step properties in Designer to specify that the step must be locked at run time. Locking a step allows it to be executed by multiple threads.

In Process Engine 7.1.1 and earlier versions, step locking was always enabled for receive and join steps, but disabled for all other step types. In Process Engine 7.1.2 and later versions, step locking is available as an option that can be enabled or disabled for each individual step.

If you plan to include parallel step execution in your process model (including referenced process steps), you must enable those steps for step locking by selecting the Allow parallel execution check box in the step's Properties view in Software AG Designer. Step locking is always recommended for use in re-entrant processes, especially during heavy processing loads. A re-entrant process is a process with multiple documents with the same correlation joining to the same instance in different paths. If step locking is not implemented, a receive step can intermittently display the waiting state.