Ensuring local activites are executed on the same machine

Community Support
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Hi all,

I am developing a workflow, which triggers independent code wich must be stopped in case of an error, stop signal, or temporal being down. Therefore I came up with the following steps:

  • 1, run a setup activity on HostA
  • 2, run an activity that initiates independent code on HostA that runs in a loop (ideally forever without intervention/error),
  • 3, update a TTL for step 2 every few seconds, ensuring code termination in case of temporal being unavailable
  • 4, stop the code on HostA by setting a flag (via cancellation, signals, or if an error occurs)

My main problem is, that I need to be sure that steps 1 to 4 are executed by the same running process/binary to guarantee termination.
I was thinking, that I could simply use local activities, which would work as long as there is only one host.
Session workers would fix the problem, but I am unsure if they can be combined - is this possible, and will work as expected?

Regarding -4, I am aware that cancellation only works with heartbeats, which are not enabled for local activities, but this is my least concern.

Thank you

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Local activity should never be used to ensure that they are executed on the same machine. Workflow can be moved to another machine at any time. Also, never use local activities for long running operations. That’s why they don’t support heartbeating,.

So, I recommend using Session. It matches your scenario perfectly.