title: Does asp.net core rest api is thread safe?
body: <p>I use singleton manager in rest api method.</p>
  
  <pre><code>[HttpGet("GetUserData")]
  public JsonResult GetUserData()
  {
      //Singleton class in rest api method
      AuthManager manager = AuthManager.GetInstance();
  
  }
  </code></pre>
  
  <p>Server will publish auth key when session(user) request login.
  And Server will save this by Dictionary. 
  The key is authkey and value is user info which include session id.</p>
  
  <p>And my rest api must be used by logged in and authorized user, so i must check first session's authorized when the session request by rest api.<br>
  So all rest api must be access that singleton auth manager class.</p>
  
  <p>But if it is not thread safe, then i must use lock (And it makes me very terrible).</p>
  
  <p>Does asp.net core's controller method (view method or rest api) is thread safe?</p>