Skip to content
m02-resource logo

Resource Management

m02-resource

CRITICAL: Use for smart pointers and resource management. Triggers: Box, Rc, Arc, Weak, RefCell, Cell, smart pointer, heap allocation, reference counting, RAII, Drop, should I use Box or Rc, when to use Arc vs Rc, 智能指针, 引用计数, 堆分配

SKILL.md

Full skill instructions

Resource Management

Layer 1: Language Mechanics

Core Question

What ownership pattern does this resource need?

Before choosing a smart pointer, understand:

  • Is ownership single or shared?
  • Is access single-threaded or multi-threaded?
  • Are there potential cycles?

Error → Design Question

ErrorDon't Just SayAsk Instead
"Need heap allocation""Use Box"Why can't this be on stack?
Rc memory leak"Use Weak"Is the cycle necessary in design?
RefCell panic"Use try_borrow"Is runtime check the right approach?
Arc overhead complaint"Accept it"Is multi-thread access actually needed?

Thinking Prompt

Before choosing a smart pointer:

  1. What's the ownership model?

    • Single owner → Box or owned value
    • Shared ownership → Rc/​Arc
    • Weak reference → Weak
  2. What's the thread context?

    • Single-thread → Rc, Cell, RefCell
    • Multi-thread → Arc, Mutex, RwLock
  3. Are there cycles?

    • Yes → One direction must be Weak
    • No → Regular Rc/​Arc is fine

Trace Up ↑

When pointer choice is unclear, trace to design:

"Should I use Arc or Rc?"
    ↑ Ask: Is this data shared across threads?
    ↑ Check: m07-concurrency (thread model)
    ↑ Check: domain-* (performance constraints)
SituationTrace ToQuestion
Rc vs Arc confusionm07-concurrencyWhat's the concurrency model?
RefCell panicsm03-mutabilityIs interior mutability right here?
Memory leaksm12-lifecycleWhere should cleanup happen?

Trace Down ↓

From design to implementation:

"Need single-owner heap data"
    ↓ Use: Box<T>

"Need shared immutable data (single-thread)"
    ↓ Use: Rc<T>

"Need shared immutable data (multi-thread)"
    ↓ Use: Arc<T>

"Need to break reference cycle"
    ↓ Use: Weak<T>

"Need shared mutable data"
    ↓ Single-thread: Rc<RefCell<T>>
    ↓ Multi-thread: Arc<Mutex<T>> or Arc<RwLock<T>>

Quick Reference

TypeOwnershipThread-SafeUse When
Box<T>SingleYesHeap allocation, recursive types
Rc<T>SharedNoSingle-thread shared ownership
Arc<T>SharedYesMulti-thread shared ownership
Weak<T>Weak refSame as Rc/​ArcBreak reference cycles
Cell<T>SingleNoInterior mutability (Copy types)
RefCell<T>SingleNoInterior mutability (runtime check)

Decision Flowchart

Need heap allocation?
├─ Yes → Single owner?
│        ├─ Yes → Box<T>
│        └─ No → Multi-thread?
│                ├─ Yes → Arc<T>
│                └─ No → Rc<T>
└─ No → Stack allocation (default)

Have reference cycles?
├─ Yes → Use Weak for one direction
└─ No → Regular Rc/​Arc

Need interior mutability?
├─ Yes → Thread-safe needed?
│        ├─ Yes → Mutex<T> or RwLock<T>
│        └─ No → T: Copy? → Cell<T> : RefCell<T>
└─ No → Use &mut T

Common Errors

ProblemCauseFix
Rc cycle leakMutual strong refsUse Weak for one direction
RefCell panicBorrow conflict at runtimeUse try_borrow or restructure
Arc overheadAtomic ops in hot pathConsider Rc if single-threaded
Box unnecessaryData fits on stackRemove Box

Anti-Patterns

Anti-PatternWhy BadBetter
Arc everywhereUnnecessary atomic overheadUse Rc for single-thread
RefCell everywhereRuntime panicsDesign clear ownership
Box for small typesUnnecessary allocationStack allocation
Ignore Weak for cyclesMemory leaksDesign parent-child with Weak

Related Skills

WhenSee
Ownership errorsm01-ownership
Interior mutability detailsm03-mutability
Multi-thread contextm07-concurrency
Resource lifecyclem12-lifecycle

More Other skills

Delegate independent tasks to specialized agents working concurrently with isolated context.

295.4K 206.3K
View

Applies Anthropic's official brand colors and typography to any sort of artifact that may benefit from having Anthropic's look-and-feel. Use it when brand colors or style guidelines, visual formatting, or company design standards apply.

179.7K 100.1K
View

Toolkit for styling artifacts with a theme. These artifacts can be slides, docs, reportings, HTML landing pages, etc. There are 10 pre-set themes with colors/fonts that you can apply to any artifact that has been creating, or can generate a new theme on-the-fly.

179.7K 89.5K
View

A set of resources to help me write all kinds of internal communications, using the formats that my company likes to use. Claude should use this skill whenever asked to write some sort of internal communications (status reports, leadership updates, 3P updates, company newsletters, FAQs, incident reports, project updates, etc.).

179.7K 76.1K
View

Fundamental design principles for writing maintainable, testable Python code.

40.2K 21.9K
View

Modern responsive layouts using container queries, fluid typography, CSS Grid, and mobile-first strategies.

40.2K 20K
View

Generate Playwright tests from scenarios using interactive browser exploration and validation.

39.7K 18.2K
View

Modern React state management with Redux Toolkit, Zustand, Jotai, and React Query for every state category.

40.2K 14.7K
View

GDPR-compliant data handling with consent management, data subject rights, and privacy controls.

40.2K 14.3K
View

Python error handling patterns including input validation, exception hierarchies, and partial failure handling. Use when implementing validation logic, designing exception strategies, handling batch processing failures, or building robust APIs.

40.2K 13.5K
View

Detailed multi-file refactor planning with safety checks and rollback guidance.

39.7K 13K
View