M07 Concurrency

The m07-concurrency skill guides developers through Rust's concurrency and async patterns by mapping errors to underlying design questions about workload type, data sharing models, and thread safety requirements. It serves Rust developers encountering Send/Sync errors, deadlocks, or race conditions, helping them diagnose whether problems stem from incorrect primitive choice (threads vs. async), sharing strategy (channels vs. Mutex), or domain-specific constraints. The skill prioritizes tracing errors upward to domain context (web APIs, fintech, CLI) before applying fixes, preventing misuse of concurrency primitives like Rc in thread-safe contexts.

skills.sh installs: 844
GitHub stars: 1.3K
last updated: Jul 14, 2026

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Install

$ npx -y skills add zhanghandong/rust-skills --skill m07-concurrency --agent claude-code

Installs into .claude/skills of the current project.

Files

Concurrency

Layer 1: Language Mechanics

Core Question

Is this CPU-bound or I/O-bound, and what's the sharing model?

Before choosing concurrency primitives:

What's the workload type?
What data needs to be shared?
What's the thread safety requirement?

Error → Design Question

Error	Don't Just Say	Ask Instead
E0277 Send	"Add Send bound"	Should this type cross threads?
E0277 Sync	"Wrap in Mutex"	Is shared access really needed?
Future not Send	"Use spawn_local"	Is async the right choice?
Deadlock	"Reorder locks"	Is the locking design correct?

Thinking Prompt

Before adding concurrency:

What's the workload?
- CPU-bound → threads (std::thread, rayon)
- I/O-bound → async (tokio, async-std)
- Mixed → hybrid approach
What's the sharing model?
- No sharing → message passing (channels)
- Immutable sharing → Arc
- Mutable sharing → Arc<Mutex> or Arc<RwLock>
What are the Send/Sync requirements?
- Cross-thread ownership → Send
- Cross-thread references → Sync
- Single-thread async → spawn_local