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Activity Cancellation and Heartbeating

This sample demonstrates:

  • How a retried Activity Task can resume from the last Activity Task's heartbeat.
  • How to handle canceling a long-running Activity when its associated Workflow is canceled.

Docs: Activity heartbeating and cancellation

Running src/client.ts does this:

  • Starts the runCancellableActivity Workflow and retains a handle to it for later use
    • The fakeProgress activity starts and heartbeats
  • Waits 40s
  • Uses the handle to cancel() the workflow
    • The activity's sleep receives the cancellation signal and throws a CancelledFailure for you to handle
    • Activity catches the CancelledFailure which you can check with isCancellation(err)
      • Prints Fake progress activity cancelled in the Worker terminal
    • Workflow prints Workflow cancelled along with its activity in the Worker terminal
  • Prints Cancelled workflow successfully
  • Calls result() demonstrate that calling result() on a workflow that is cancelled will throw a WorkflowFailedError with a cause of CancelledFailure.
  • The WorkflowFailedError is caught and we print handle.result() threw because Workflow was cancelled

Running this sample

  1. temporal server start-dev to start Temporal Server.
  2. npm install to install dependencies (or pnpm or yarn).
  3. npm run start to start the Worker.
  4. In another shell, npm run workflow to run the Workflow.
  5. In the first shell, watch the Worker output for a few seconds:
Starting activity at progress: 1
Progress: 1
Progress: 2
Progress: 3
Progress: 4
Progress: 5
Progress: 6
Progress: 7
^C
  1. Hit Ctrl-C to kill the Worker.
  2. Wait 5 seconds (long enough for heartbeatTimeout: '3s' to lapse and the Activity to be rescheduled.)
  3. npm run start to start the Worker again:
Starting activity at progress: 4
Progress: 4
Progress: 5
Progress: 6
Progress: 7
Progress: 8
Progress: 9
Progress: 10
Progress: 11
Progress: 12
Progress: 13
Progress: 14
Progress: 15
Progress: 16
Progress: 17
Progress: 18
Progress: 19
Progress: 20
Progress: 21
Progress: 22
Progress: 23
Progress: 24
Fake progress activity cancelled
[runCancellableActivity(cancellation-heartbeating-0)] Workflow cancelled along with its activity
  1. In the other shell, where the client code is running (npm run workflow), the output should be:
Cancelled workflow successfully
handle.result() threw because Workflow was cancelled