tml#proxy.timeout.io"><code>proxy.timeout.*</code></a>) are applied to the requests that are issued by the <code>http_request</code> method.
</p>

<h3 id="logging-arbitrary-variable">Logging Arbitrary Variable</h3>

<p>
In version 2.3, it is possible from mruby to set and log an arbitrary-named variable that is associated to a HTTP request.
A HTTP response header that starts with <code>x-fallthru-set-</code> is handled specially by the H2O server. Instead of sending the header downstream, the server accepts