Remove need for mutex in example snippet since r2d2 internally maintains its own sync mechanism
//! use diesel::r2d2::ConnectionManager;
//! use diesel::r2d2::Pool;
//! use std::env;
-//! use std::sync::Arc;
-//! use std::sync::Mutex;
//! use std::thread;
//!
//! pub type PostgresPool = Pool<ConnectionManager<PgConnection>>;
//!
//! fn main() {
//! let pool_size = 1;
-//! let connection_pool = Arc::new(Mutex::new(get_connection_pool(pool_size)));
-//! setup_user_table(&mut connection_pool.lock().unwrap().get().unwrap());
+//! let pool = get_connection_pool(pool_size);
+//! setup_user_table(&mut pool.get().unwrap());
//!
//! let mut threads = vec![];
//! let max_users_to_create = 1;
//!
//! for i in 0..max_users_to_create {
-//! let connection_pool = Arc::clone(&connection_pool);
+//! let pool = pool.clone();
//! threads.push(thread::spawn({
//! move || {
-//! let connection_pool = connection_pool.lock().unwrap();
-//! let conn = &mut connection_pool.get().unwrap();
+//! let conn = &mut pool.get().unwrap();
//! let name = format!("Person {}", i);
//! create_user(conn, &name).unwrap();
//! }
//! handle.join().unwrap();
//! }
//!
-//! delete_user_table(&mut connection_pool.lock().unwrap().get().unwrap());
+//! delete_user_table(&mut pool.get().unwrap());
//! }
//! ```
//!
