concurrency-deity

concurrency-deity is a skill for Claude Code from v0idOS/performance-deity. It costs 0 tokens per session (325 once invoked), scanned A, original, MIT.

A skill focused on deliberately exposing race conditions and deadlocks in concurrent code, then adding synchronization to protect it.

In plain words
What is it for?
Use it when testing threading, asynchronous code, multithreading, or shared state, including writing high-concurrency tests and choosing an appropriate synchronization method.
Why use it?
It helps reveal failures that may appear only when threads, asynchronous tasks, promises, or goroutines overlap.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the performance-deity plugin — 17 skills shipped together

Good fit Use it when testing threading, asynchronous code, multithreading, or shared state, including writing high-concurrency tests and choosing an appropriate synchronization method.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/v0idos/performance-deity/concurrency-deity
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 v0idOS/performance-deity --skill concurrency-deity
Clone the repo
git clone --depth 1 https://github.com/v0idOS/performance-deity

Made for: Claude Code.

Or install performance-deity, the plugin that ships this one along with the rest of its 17 skills.

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.

agentmods badge for concurrency-deity

README.md
[![agentmods](https://agentmods.dev/badge/skills/v0idos/performance-deity/concurrency-deity.svg)](https://agentmods.dev/skills/v0idos/performance-deity/concurrency-deity)
Your own site
<a href="https://agentmods.dev/skills/v0idos/performance-deity/concurrency-deity"><img src="https://agentmods.dev/badge/skills/v0idos/performance-deity/concurrency-deity.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 325 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.00325
Opus 5 $0.00000 $0.00162
Sonnet 5 $0.00000 $0.00065
Haiku 4.5 $0.00000 $0.00032

Measured 7d ago against content hash d0dd174947f0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

concurrency-deity 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 7d ago.

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.

archive/concurrency-deity/SKILL.md · 32 lines

What it actually says

Concurrency Deity: The Race Condition Killer

Description

This skill is designed to deliberately cause race conditions and deadlocks, prove they exist, and then secure the codebase using proper synchronization primitives.

Triggers

Activate when the user mentions:

  • "threading", "multithreading"
  • "async", "promises", "goroutines"
  • "race condition", "deadlock"
  • Or explicitly runs /plugin performance-deity:concurrency

Core Directives

Phase 1: The Chaos Script

  1. Write a Chaos Test that fires at least 1,000 asynchronous/concurrent requests/threads at the target function simultaneously.
  2. The test must assert the final state (e.g., if incrementing a counter 1000 times, the final value MUST be exactly 1000).

Phase 2: Failure Verification

  1. Run the Chaos Test.
  2. If it passes consistently, increase the concurrency limit or add artificial sleep delays mid-execution to force thread context switching. You must prove the function is unsafe before fixing it.

Phase 3: Synchronization

  1. Implement the fastest possible synchronization primitive:
    • Prefer Atomic operations over Mutexes.
    • Prefer Mutexes/Locks over heavy Semaphores.
    • Ensure Lock scopes are as small as physically possible to prevent bottlenecking.

Phase 4: Proof

  1. Re-run the Chaos Test with 10,000 concurrent requests.
  2. Present the user with the locked/atomic code and the test results proving 0% failure rate under extreme concurrency.
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.

  1. 7d ago First seen · 32 lines · 0 tokens per session scan A d0dd174947f0

Subscribe to this mod's changes

concurrency-deity is a skill published in the GitHub repository v0idOS/performance-deity (2 stars, last pushed 4mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 325 tokens. 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 2026-08-31.

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