Parking Lot
A Rust library for resource-aware background work, bounded execution and collecting results after the request that started them has returned.
Released v0.3.0 on crates.io · 24 Oct 2026
Key facts
- How it works
- Each task declares a cost; a pool starts it when the cost fits free capacity and parks it otherwise.
- Ordering
- Parked tasks start by priority, then in submission order; a task costing more than the pool's capacity is rejected.
- Durable mode
- Tasks can be parked in a Postgres or redb queue so accepted work survives a crash.
- Registry
- Published on crates.io; registry publication is not runtime qualification.
- Used by
- The Candle-VLLM Prometheus fork submits completion and streaming work through a pool.
Questions worth asking
- When would I use Parking Lot?
- How does Parking Lot decide which task starts next?
- Can Parking Lot keep work across a crash?