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Eager Workflow Start

2 posts · Apr 2024 – Feb 2025

What this trail covers

Eager Workflow Start (EWS) is an experimental optimization that reduces the time to start a workflow by allowing the starter and worker to interact directly, bypassing some server operations. The start response with EWS includes the initial workflow task when there is a local worker ready to process it. This is particularly useful for short-lived workflows that interact with other services using local activities and are deployed close to the Temporal Server. The current implementation has limitations, requiring the worker and starter to share a client connection and run in the same process. It does not yet support worker versioning with build IDs. EWS is enabled via a dynamic configuration flag and is available in Temporal Cloud via a support ticket.

All Temporal trails
  1. Reduce end-user latency and accelerate Temporal WorkflowsThis post details the Eager Workflow Start (EWS) feature, an optimization that reduces workflow startup latency by enabling direct interaction between the client and a local worker, bypassing some Temporal Server operations. It explains how EWS provides the initial workflow task in the start response when a local worker is ready, making it beneficial for short-lived workflows and those using local activities deployed near the Temporal Server. The post also touches on the limitations of the current EWS implementation.
  2. Improving latency with Eager Workflow Start in TemporalThis post introduces Eager Workflow Start (EWS), an experimental feature designed to reduce workflow start latency. It details the mechanism by which EWS bypasses server matching operations by allowing a local worker to directly receive the first workflow task. Performance improvements are quantified with p50 and p99 latency reductions of 43% and 40% respectively in test scenarios. Limitations include the requirement for co-located starters and workers sharing a client connection, and the current lack of support for worker versioning with build IDs. A 'Hello World' example in Go demonstrates how to implement EWS by starting the worker in non-blocking mode and setting the `EnableEagerStart` flag.