title: When would you use a Mutex without an Arc?
body: <p>An extremely common pattern in Rust is <code>Arc&lt;Mutex&lt;T&gt;&gt;</code>, where <code>Arc</code> provides the memory management, and <code>Mutex</code> provides safe multi-threaded access to the resource. What else <em>could</em> be used in place of <code>Arc</code>, and under what circumstances?</p>