parking_lot (Rust)
High-performance synchronization primitives for Rust that replace std::sync::Mutex, RwLock, and Condvar. parking_lot's Mutex is significantly smaller (1 byte vs 40 bytes), faster, and supports additional features like fair locking, try_lock_for with timeout, and deadlock detection in debug mode. Does not poison on panic (unlike std Mutex). Used by many high-performance Rust crates.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Memory safety guaranteed by Rust. No poisoning behavior means panics in locked sections require careful application design. No known security vulnerabilities.
⚡ Reliability
Best When
You're using synchronous Rust code and want faster, smaller, feature-richer synchronization primitives than std::sync provides.
Avoid When
You're writing async code — use tokio::sync equivalents. Or if you need lock poisoning semantics from std.
Use Cases
- • Replace std::sync::Mutex with parking_lot::Mutex for better performance and smaller memory footprint
- • Use try_lock_for(Duration) with timeout to avoid indefinite blocking in time-sensitive concurrent code
- • Enable deadlock detection in development builds via the deadlock_detection cargo feature
- • Use parking_lot::RwLock for reader-writer locking with fair scheduling to prevent writer starvation
- • Avoid mutex poisoning issues — parking_lot locks remain usable after thread panics unlike std::sync::Mutex
Not For
- • Async code with Tokio — parking_lot is synchronous; use tokio::sync::Mutex for async-safe locking
- • Applications where lock poisoning (std behavior) is a desired safety feature
- • Code that needs to run in no_std environments — parking_lot requires OS thread parking
Interface
Authentication
Library with no auth requirement.
Pricing
Free and open source.
Agent Metadata
Known Gotchas
- ⚠ parking_lot Mutex does NOT poison on panic — unlike std::sync::Mutex which returns PoisonError after a thread panics, parking_lot continues working; this can hide bugs where data is in inconsistent state after panic
- ⚠ Holding a parking_lot MutexGuard across an .await point causes deadlocks in async code — tokio::sync::Mutex is designed for async; use it instead
- ⚠ parking_lot's lock() method never fails (no PoisonError) — code that was handling PoisonError from std::sync should remove that handling when migrating to parking_lot
- ⚠ fair() locking mode prevents starvation but reduces throughput — only use fair locking when writer/reader starvation is observed, not by default
- ⚠ Deadlock detection requires enabling the 'deadlock_detection' cargo feature AND calling deadlock::check_deadlock() periodically — it's not automatic
- ⚠ parking_lot Mutex is not Send across async boundary — wrap in Arc<parking_lot::Mutex> for shared ownership; same as std but important to remember when migrating
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for parking_lot (Rust).
Scores are editorial opinions as of 2026-03-06.