# Distributed Locking

> Implement safe distributed locks and coordination primitives when mutual exclusion is required across processes or services. Use when preventing double-processing, leader election, or coordinating work in a distributed system.

- Skill: `itsual/distributed-locking` (Agent Skill)
- Install (CLI): `npx skillmds@latest add itsual/distributed-locking`
- Raw SKILL.md: https://api.skillmd.com/api/skills/itsual/distributed-locking/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: itsual (https://skillmd.com/u/itsual)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/itsual/distributed-locking

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# Distributed Locking

## Overview

Distributed locks are easy to get subtly wrong. Prefer designs that minimize the need for them, and when required, use well-understood patterns and libraries.

## When to Use

- Ensuring only one worker processes a critical section
- Leader election or singleton tasks
- Preventing duplicate side effects under concurrency

## Key Considerations

- Lock correctness under process pauses, network partitions, and clock issues
- Lock timeout / fencing token needs
- Deadlock and lock-ordering risks
- Performance and availability impact of the lock service

## Principles

- Prefer idempotent designs that reduce the need for strict locking
- Use battle-tested implementations (Redis, etcd, ZooKeeper, database advisory locks, etc.) carefully
- Always consider what happens if the lock holder dies
- Prefer fencing tokens when the lock protects external side effects

## Verification

- Concurrent execution cannot produce incorrect duplicate effects
- Lock failure modes are understood and tested
- No single point of failure is introduced without justification