What is tokio-performance?

A guide for improving asynchronous Rust programs that use Tokio, a library for running many tasks without blocking the main thread. It covers throughput, response time, fairness, locks, channels, blocking work, and limits on concurrent tasks.

Use it to review Tokio runtime design, choose between direct execution and blocking worker threads, tune task scheduling, and investigate contention or slow tail responses.

It helps avoid performance changes based on assumptions, such as treating all asynchronous code as faster or creating more tasks without measuring the result.

tokio-performance — Skill for Claude Code and Codex by d-oit

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add d-oit/rust-2026-template --skill tokio-performance

Clone the repo

git clone --depth 1 https://github.com/d-oit/rust-2026-template

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/d-oit/rust-2026-template/tokio-performance/github.svg)](https://agentmods.dev/skills/d-oit/rust-2026-template/tokio-performance)

Your own site

<a href="https://agentmods.dev/skills/d-oit/rust-2026-template/tokio-performance"><img src="https://agentmods.dev/badge/skills/d-oit/rust-2026-template/tokio-performance/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/d-oit/rust-2026-template/tokio-performance"><img src="https://agentmods.dev/badge/skills/d-oit/rust-2026-template/tokio-performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 60 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,750 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00060	$0.02750
Opus 5.5	$0.00024	$0.01100
Sonnet 5.5	$0.00012	$0.00550
Haiku 4.5	$0.00006	$0.00275

Measured today against content hash 9c0481bdfd80, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

tokio-performance scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/tokio-performance/SKILL.md · 179 lines

How it starts

The opening of the file, as written. The whole thing — 179 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Tokio Performance

Performance guidance for production Rust systems using Tokio. Optimize measured behavior from workload characteristics, not async code by reflex.

Core Rule

Measure first. Derive execution models, concurrency bounds, and lock strategies from workload characteristics.

Do not assume:

async is faster than synchronous code
spawn_blocking is always better for CPU work
tokio::sync::Mutex or RwLock is preferable to a synchronous lock or atomic/snapshot pattern
more tasks or more runtimes mean more throughput
yield_now() everywhere improves fairness

Workload Decision Matrix

Workload Type	Characteristics	Recommended Execution Model	Key Considerations
Short Bounded CPU	Fast, non-blocking calculations (< 10–100 µs), memory parsing, small serializations	Direct Execution on Tokio Worker	Offloading to `spawn_blocking` introduces thread context switches and queue overhead that exceed the work duration.
Genuinely Blocking	Synchronous disk I/O, blocking C/FFI calls, legacy blocking SDKs, blocking DB drivers	`spawn_blocking` or Dedicated Thread Pool	Prevents blocking the Tokio worker thread event loop.
Long or Sustained CPU	Image processing, heavy cryptography, compression, large payload parsing (> 100 µs - ms+)	`spawn_blocking` or Dedicated Worker Pool	Protects Tokio worker threads from starvation. For sustained heavy CPU, prefer a dedicated Rayon/thread pool to avoid exhausting Tokio's blocking pool.
Batchable Operations	High-rate small I/O operations, frequent channel sends, small database updates	Batching & Micro-buffering	Consolidates syscalls, locks, and channel synchronization overhead.
Isolated Subsystems	Multi-tenant latency isolation, distinct thread priority requirements	Workload Isolation	Isolate via bounded semaphores or separate thread pools before considering a separate Tokio runtime.

Correctness vs. Performance Heuristics

Read the full file on GitHub · 179 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

today Changed · +2 lines 9c0481bdfd80
1mo ago Changed · -86 lines 9e165085b6a8
1mo ago Changed · +13 lines 3252c2f6e385
1mo ago First seen · 250 lines · 60 tokens per session scan A 5f6fcfa1eafa

Subscribe to this mod's changes

tokio-performance is a skill published in the GitHub repository d-oit/rust-2026-template (15 stars, last pushed yesterday), licensed MIT. It adds 60 tokens to every session and 2,750 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-18.

Debugging Languages Rust ai-agents ai-tooling template

tokio-performance next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
tokio-performanced-oit/rust-2026-template	Skill	15	yesterday	MIT	A	60	Claude Code, Codex
rust-checkHmbown/CodeWhale	Skill	41k	6d ago	MIT	A	15	Claude Code, Codex
stack-trace-rust-probeopensquilla/opensquilla	Skill	7.1k	8d ago	Apache-2.0	A	42	Claude Code
hotpath_initpawurb/hotpath-rs	Skill	1.9k	7d ago	MIT	A	88	Claude Code
memory-safety-patternsrmyndharis/antigravity-skills	Skill	2.0k	7d ago	MIT	A	45	Claude Code, Codex
rust-errorBerriAI/litellm	Skill	63k	today	none	A	72	Claude Code, Codex
rust-tracingBerriAI/litellm	Skill	63k	today	none	A	28	Claude Code, Codex