Folly does not use boost::asio, but rather libevent:<p><pre><code>  libevent is an excellent cross-platform eventing library.
  Folly&#x27;s async provides C++ object wrappers for fd callbacks
  and event_base, as well as providing implementations for
  many common types of fd uses.
</code></pre>
<a href="https:&#x2F;&#x2F;github.com&#x2F;facebook&#x2F;folly&#x2F;blob&#x2F;master&#x2F;folly&#x2F;io&#x2F;async&#x2F;README.md" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;facebook&#x2F;folly&#x2F;blob&#x2F;master&#x2F;folly&#x2F;io&#x2F;async...</a><p>grepping the codebase for `asio` brings up nothing.