r2d2 0.8.10

A generic connection pool



A generic connection pool for Rust.


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.

r2d2 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 adaptors for different backends:

Backend Adaptor Crate
rust-postgres r2d2-postgres
redis-rs use r2d2 feature of redis-rs
rust-memcache r2d2-memcache
rust-mysql-simple r2d2-mysql
rusqlite r2d2-sqlite
rsfbclient r2d2-firebird
rusted-cypher r2d2-cypher
diesel diesel::r2d2 (docs)
couchdb r2d2-couchdb
mongodb (archived)use official mongodb driver instead r2d2-mongodb(deprecated: official driver handles pooling internally)
odbc r2d2-odbc
jfs r2d2-jfs
oracle r2d2-oracle
ldap3 r2d2-ldap
duckdb-rs use r2d2 feature of duckdb-rs


Using an imaginary "foodb" database.

use std::thread;

extern crate r2d2;
extern crate r2d2_foodb;

fn main() {
    let manager = r2d2_foodb::FooConnectionManager::new("localhost:1234");
    let pool = r2d2::Pool::builder()

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


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