envoyproxy/envoy

Configure V8 DefaultWorker threads in yaml

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#38,680 opened on Mar 7, 2025

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area/wasmhelp wanted

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Description

We are using the wasmervice bootstrap extension in yaml as below

bootstrap_extensions:

  • name: envoy.bootstrap.wasm typed_config: "@type": type.googleapis.com/envoy.extensions.wasm.v3.WasmService singleton: true

When we have this in the yaml even after marking "singleton : true" we see 16 "V8 DefaultWorker" threads started on a 32 cpu box. Is there a way to limit these in the yaml with some parameter ? Or do I have to change code and rebuild envoy ? --concurrency doesn't help in configuring these as that is only for worker threads. Tried doing a google search for this issue but nothing turns up.

Contributor guide

Research direction
Investigate how Envoy's Wasm extension initializes V8 and identify where to add a config option for limiting DefaultWorker threads.
Tech stack
cpp
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitC++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50