Awesome Open Source
Awesome Open Source


Documentation Build status codecov License: MIT

A full-featured connection pool, designed for asynchronous connections (using tokio). Originally based on r2d2.

Opening a new database connection every time one is needed is both inefficient and can lead to resource exhaustion under high traffic conditions. A connection pool maintains a set of open connections to a database, handing them out for repeated use.

bb8 is agnostic to the connection type it is managing. Implementors of the ManageConnection trait provide the database-specific logic to create and check the health of connections.

A (possibly not exhaustive) list of adapters for different backends:

Backend Adapter Crate
tokio-postgres bb8-postgres (in-tree)
redis bb8-redis (in-tree)
rsmq rsmq_async
bolt-client bb8-bolt
diesel bb8-diesel
tiberius bb8-tiberius
nebula-graph-client bb8-nebula-graph
memcache-async bb8-memcached
lapin bb8-lapin


Using an imaginary "foodb" database.

fn main() {
    let manager = bb8_foodb::FooConnectionManager::new("localhost:1234");
    let pool = bb8::Pool::builder()

    for _ in 0..20 {
        let pool = pool.clone();
        tokio::spawn(move || {
            let conn = pool.get().await.unwrap();
            // use the connection
            // it will be returned to the pool when it falls out of scope.


Licensed under the MIT license (LICENSE).


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be licensed as above, without any additional terms or conditions.

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