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Parallel gateway

A Parallel (AND) gateway splits the flow into all outgoing paths at once — no conditions involved — and, as a join, waits until a token has arrived on every incoming flow before continuing. Fork and join are usually used as a pair enclosing the parallel section.

Parallel gateway

Rendered as a diamond with a plus marker.

Use cases​

  • Independent work in parallel — run a credit check and an identity verification at the same time instead of one after the other.
  • Synchronize before a decision — wait until all parallel checks have completed before the process continues to the loan decision.
  • Fan out notifications — trigger several unconditional side activities at once after a milestone.

Usage in BPMN​

A Parallel gateway needs no configuration — no conditions, no default flow. Condition expressions on its outgoing flows are ignored.

Execution flow when diverging:

  1. A token arrives at the gateway.
  2. A separate token is created for every outgoing sequence flow, unconditionally, and all branches run in parallel.

Execution flow when converging (multiple incoming flows):

  1. Each arriving token waits at the gateway.
  2. When tokens have arrived on all incoming flows, the gateway fires: the waiting tokens are consumed and one token is created per outgoing flow.

For running the same activity many times in parallel — once per element of a collection — use a multi-instance activity instead of modelling parallel branches explicitly.

Limitation

The join synchronizes correctly for a single parallel section at a time. Nested or overlapping parallel sections flowing through the same joining gateway concurrently have undefined behaviour.

XML example​

A loan application forks into a credit check and an identity check; the joining gateway waits for both results before the decision:

<bpmn:parallelGateway id="Gateway_ForkChecks" name="Run checks">
  <bpmn:incoming>Flow_In</bpmn:incoming>
  <bpmn:outgoing>Flow_CreditCheck</bpmn:outgoing>
  <bpmn:outgoing>Flow_IdCheck</bpmn:outgoing>
</bpmn:parallelGateway>

<bpmn:parallelGateway id="Gateway_JoinChecks" name="All checks done">
  <bpmn:incoming>Flow_CreditResult</bpmn:incoming>
  <bpmn:incoming>Flow_IdResult</bpmn:incoming>
  <bpmn:outgoing>Flow_Decision</bpmn:outgoing>
</bpmn:parallelGateway>