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Report poller target on poll requests and in the worker heartbeat - #887
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Workers report the poller target of the pool issuing each poll so the server can distribute poller-scaling suggestions fairly across a fleet. Scaling suggestions ride on dispatched tasks and the matcher is FIFO, so a worker's share of suggestions tracks its share of pollers. Growth is therefore proportional to current size, which preserves any imbalance between otherwise identical workers rather than correcting it. With a reported target the server can withhold suggestions that would push a worker further from its share.
This was referenced Oct 20, 2026
Sushisource
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Oct 20, 2026
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| // Scaling suggestions ride on dispatched tasks, and the matcher hands tasks to waiting | ||
| // pollers in FIFO order, so a worker holding a large share of a task queue's pollers | ||
| // receives suggestions at a proportionally higher rate. That makes poller growth | ||
| // proportional to current poller count, which preserves and amplifies any imbalance | ||
| // between otherwise identical workers. Reporting this lets the server withhold | ||
| // suggestions that would push a worker further from its share. |
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I dunno that this needs to go into detail about the specific motivating problem. Can probably just drop the whole paragraph honestly.
Co-authored-by: Spencer Judge <spencer@temporal.io>
veeral-patel
marked this pull request as ready for review
October 20, 2026 20:11
Workers already report their poller target on each poll so matching can spread scaling suggestions across a fleet by share. That value is consumed inside the matching decision and discarded -- nothing persists it, and nothing can observe it. Reporting it on the heartbeat as well lets the server read poller target per worker and export it as a metric, making fleet-wide poller distribution visible without instrumenting every SDK. WorkerHeartbeat already carries four separate WorkerPollerInfo sub-messages (workflow, sticky workflow, activity, nexus), so a single field here gives a per-task-type breakdown without a new keyed structure, and keeps the normal-vs-sticky split that TaskQueueType cannot express.
veeral-patel
changed the title
Drop the rich-get-richer explanation from PollerScalingInfo: it is rationale for the server's matching logic rather than anything a client needs to populate the field, and it will go stale independently of this proto. The rest just says less of the same thing, matching the one-to-two line style of the surrounding fields.
Sushisource
approved these changes
Oct 22, 2026
CI runs 'make ci-build' and fails if the tree is dirty, and the checked-in OpenAPI specs are generated output. WorkerHeartbeat is reachable over the HTTP API via RecordWorkerHeartbeat, so adding a field to WorkerPollerInfo changes them. The poll-request field needed no regeneration -- the poll RPCs have no HTTP binding.
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What
Adds a worker-reported poller target in two places.
1. On each poll — a new
PollerScalingInfointemporal.api.taskqueue.v1, attached as field 11 toPollWorkflowTaskQueueRequestandPollActivityTaskQueueRequest:2. On the worker heartbeat — a new field on
WorkerPollerInfo:Why
Sending poller target in each poll will allow us to apply logic to load balance pollers between workers. Sending poller target on the worker heartbeat will let us export a poller target metric on the server side.