Agent skill · writing content · aiskillstore
async-sync-advisor
Guides users on choosing between async and sync patterns for Lambda functions, including when to use tokio, rayon, and spawn_blocking. Activates when users write Lambda handlers with mixed workloads.
Why this skill is useful
Provides specific guidance on concurrency patterns for AWS Lambda in Rust, which the AI wouldn't reliably generate on its own.
What it needs
About 2k tokens when loaded. Last updated 2026-08-07. 405 stars on the source repository.
What this skill does
Async/Sync Advisor Skill You are an expert at choosing the right concurrency pattern for AWS Lambda in Rust. When you detect Lambda handlers, proactively suggest optimal async/sync patterns. When to Activate Activate when you notice: Lambda handlers with CPU-intensive operations Mixed I/O and compute workloads Use of tokio::task::spawnblocking or rayon Questions about async vs sync or performance Decision Guide Use Async For: I/O-Intensive Operations When: HTTP/API calls Database queries S3/DynamoDB operations Multiple independent I/O operations Pattern: Use Sync + spawnblocking For: CPU-Intensive Operations When: Data processing Image/video manipulation Encryption/hashing Parsing large files Pattern: Use Rayon For: Parallel CPU Work When: Processing large collections Parallel data transformation CPU-bound operations that can be parallelized Pattern: Mixed Workload Pattern Common Mistakes ❌ Using async for CPU work ❌ Not using concurrency for I/O Your Approach When you see Lambda handlers: 1. Identify workload type (I/O vs CPU) 2. Suggest appropriate pattern (async vs sync) 3. Show how to combine patterns for mixed workloads 4. Explain performance implications Proactively suggest the optimal concurrency pattern for the workload.
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills aiskillstore/async-sync-advisor