Note: This crate is still in early development and undergoing API changes. Contributions, feature requests, and constructive feedback are warmly welcomed.
Sharded provides safe, fast, and obvious concurrent collections in Rust. This crate splits the
underlying collection into N shards each with its own lock. Calling read(key) or write(key)
returns a guard for a single shard.
Zero unsafe code. This library uses #![forbid(unsafe_code)]. There are some limitations with the
raw locking API that could cause you to write a bug, but it should be hard to so!
Zero dependencies. By default, the library only uses std. If you'd like to pull in some community
crates such as parking_lot, just use the corresponding feature.
Tiny footprint. The core logic is ~100 lines of code. This may build up over time as utilities and ergonomics are added.
~~Extremely fast. This implementation may be a more performant choice for your workload than some of the most popular concurrent hashmaps out there.~~ ??
Flexible API.. Bring your own lock or collection types. sharded::Map is just a type alias for
Shard<Lock<Collection<_>>>. There's support for Sets and Trees, too!
java.util.concurrent.ConcurrentHashMap to Rust. (Also part of a live stream series)```toml [dependencies]
parking_lot (or crossbeam), hashbrown, and ahashsharded = { version = "0.0.1", features = ["parking_lot", "hashbrown", "ahash"] } ```
Use a concurrent HashMap
```rust use sharded::Map; let concurrent = Map::new()
// or use an existing HashMap,
let users = Shard::from(users);
let guard = users.write(32); guard.insert(32, user); ```
Disclaimer: I'm no expert in performance testing. Probably the best you can do is benchmark your application using the different implementations in the most realistic setting possible.
These measurements were generated using jonhoo/bustle. To reproduce the charts,
see the benchmarks directory. Work is underway to automate testing on a battery of cloud instance types and parameters.
Please raise a PR/issue if you have suggestions on how to improve these benchmarks or new
workloads to try!
This ran each implementation over the presets in bustle::Mix for 5
iterations/random seeds. Lower numbers are better. Approaches using a single std::sync Lock and chashmap were discarded for clarity (they are
a lot slower). If you know why chashmap is so slow in this test, please help here.
All implementations are pretty close but sharded wins by some margin until the high thread counts. At threads=1,
sharded shows a significant advantage. dashmap shows the worst overall performance.
Many thanks to
Reddit community for a few pointers and some motivation to take this project further.
Jon Gjengset for the live streams and utility crates involved
and countless OSS contributors that made this work possible
Licensed under either of Apache License, Version 2.0 or MIT license at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in sharded by you, as defined in the Apache-2.0 license, shall be
dual licensed as above, without any additional terms or conditions.