💥 Nexus support in worker tuner #1066

dandavison · 2025-08-28T22:50:12Z

Add support for nexus in WorkerTuner and support max_concurrent_nexus_tasks worker config option
Add tests for nexus worker concurrency parameters

💥 This is a breaking change: create_composite() has gained a required nexus_supplier parameter.

tconley1428 · 2025-09-05T15:35:23Z

temporalio/worker/_tuning.py

        return temporalio.bridge.worker.FixedSizeSlotSupplier(slot_supplier.num_slots)
    elif isinstance(slot_supplier, ResourceBasedSlotSupplier):
        min_slots = 5 if kind == "workflow" else 1
-        max_slots = _DEFAULT_RESOURCE_ACTIVITY_MAX


Is this a bug fix?

No, we're now using the constant for both activities and nexus operation so I renamed it.

cretz

LGTM, only blocking concern is one of backwards compatibility break

cretz · 2025-09-05T15:48:00Z

temporalio/bridge/sdk-core

Assuming we can't merge this until temporalio/sdk-core#994 is merged?

That's right

cretz · 2025-09-05T15:53:13Z

temporalio/worker/_tuning.py

-            return ss.num_slots
-        elif isinstance(ss, ResourceBasedSlotSupplier):
-            return ss.slot_config.maximum_slots or _DEFAULT_RESOURCE_ACTIVITY_MAX
+        return self._get_slot_supplier_max(self._get_activity_task_slot_supplier())


_get_slot_supplier_max is a static call, not sure if self. is the right thing

Thanks, Python allows referencing staticmethods on self but I agree I shouldn't do it and perhaps they could be shadowed by an instance method. Changed.

cretz · 2025-09-05T15:56:39Z

temporalio/worker/_tuning.py

        activity_slots: Optional[int],
        local_activity_slots: Optional[int],
-    ) -> "WorkerTuner":
+        nexus_slots: Optional[int],


This additional required parameter and the additional required parameter on create_composite are technically backwards incompatible. I think tuning is still experimental, but that may only be custom slot suppliers. I think it's worth confirming whether these two static methods are considered GA and if they are, we may need to provide acceptable defaults (here is easy, it can be None, for create_composite, just a fixed size supplier is probably the default but at runtime per call, not global shared). If these are not considered GA, we can just add a 💥 note here and in release notes.

Good catch. I've updated the PR to make it backwards compatible. I've made it so that nexus is consistent with the workflow/activity/LA by giving them all defaults.

I think that can make sense for create_fixed, but made a comment just now concerning create_composite

cretz · 2025-09-11T15:45:54Z

temporalio/worker/_tuning.py

        )

    @staticmethod
    def create_composite(


I think we explicitly designed this to require people to provide at least the first 3 suppliers when creating a composite tuner and I think we've done that across every SDK consistently. I noticed that both Go and Java added the requirement for a Nexus slot supplier as a potentially breaking change, but maybe they got it in before tuning was GA? Or maybe they considered the breaking change acceptable?

I think we should try to do this part somewhat consistently across SDKs. Can you confirm 1) whether we want to require users provide explicit slot suppliers (at least for the first 3 types) when creating a composite tuner? and 2) whether we are ok with a backwards incompatible change to require Nexus slot supplier when creating a composite tuner? (note only some languages require the first 3 values for fixed, Go does not)

We discussed offline and agreed to break create_composite while adding defaults to all for create_fixed. PR updated.

dandavison force-pushed the dan-9989-nexus-worker-tuner branch 3 times, most recently from 9720da1 to c9567a6 Compare September 3, 2025 21:15

dandavison marked this pull request as ready for review September 3, 2025 21:37

dandavison requested a review from a team as a code owner September 3, 2025 21:37

dandavison force-pushed the dan-9989-nexus-worker-tuner branch from f9134fe to 189effe Compare September 4, 2025 18:56

dandavison marked this pull request as draft September 4, 2025 18:57

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch 3 times, most recently from 563f093 to c9c99ea Compare September 5, 2025 01:59

dandavison marked this pull request as ready for review September 5, 2025 02:04

dandavison force-pushed the dan-9989-nexus-worker-tuner branch 2 times, most recently from d551ef2 to ed72439 Compare September 5, 2025 02:14

dandavison mentioned this pull request Sep 5, 2025

Enable slot supplier for nexus pollers temporalio/sdk-core#994

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch 4 times, most recently from fcbb9de to cd8ad93 Compare September 5, 2025 15:01

tconley1428 reviewed Sep 5, 2025

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cretz reviewed Sep 5, 2025

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch 2 times, most recently from f41641b to bad9bb8 Compare September 8, 2025 15:45

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch 5 times, most recently from e5958c9 to 769fd82 Compare September 10, 2025 22:07

cretz reviewed Sep 11, 2025

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch from 769fd82 to 16bf494 Compare September 11, 2025 15:54

dandavison changed the title ~~Nexus support in worker tuner~~ 💥 Nexus support in worker tuner Sep 11, 2025

cretz approved these changes Sep 11, 2025

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dandavison force-pushed the dan-9989-nexus-worker-tuner branch 2 times, most recently from a694631 to 34b6326 Compare September 12, 2025 14:43

Nexus worker concurrency control

f6036bf

dandavison force-pushed the dan-9989-nexus-worker-tuner branch from 34b6326 to f6036bf Compare September 13, 2025 04:26

dandavison merged commit 84b184f into main Sep 13, 2025
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dandavison deleted the dan-9989-nexus-worker-tuner branch September 13, 2025 17:40

💥 Nexus support in worker tuner #1066

💥 Nexus support in worker tuner #1066

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dandavison commented Aug 28, 2025 •

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