>execution_context</code></a>
          function, or any function associated with the execution_context's derived
          class, is being called in another thread. It is, however, safe to call
          this function from within a completion handler, provided no other thread
          is accessing the <a class="link" href="../execution_context.html" title="execution_context"><code class="computeroutput">execution_context</code></a>
          or its derived class.
        </p>
<h6>
<a name="boost_asio.refe