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authorStefan Eissing <icing@apache.org>2016-10-21 11:34:56 +0200
committerStefan Eissing <icing@apache.org>2016-10-21 11:34:56 +0200
commitfac9b336ca32e85ae1203281949f985837ff7575 (patch)
treefbdb8e47e3a05e3fda7cbc33ff3f65e7962187d5 /docs/manual
parenteol-style = native (diff)
downloadapache2-fac9b336ca32e85ae1203281949f985837ff7575.tar.xz
apache2-fac9b336ca32e85ae1203281949f985837ff7575.zip
added mpm advice to http2 howto
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1765974 13f79535-47bb-0310-9956-ffa450edef68
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diff --git a/docs/manual/howto/http2.xml b/docs/manual/howto/http2.xml
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@@ -154,6 +154,25 @@ ProtocolsHonorOrder Off
how to manage multiple hosts with the same certificate</a>.</p>
</section>
+ <section id="mpm-config">
+ <title>MPM Configuration</title>
+
+ <p>HTTP/2 is supported in all multi-processing modules that come with httpd. However, if
+ you use the <code>prefork</code> mpm, there will be severe restrictions.</p>
+ <p>In <code>prefork</code> <code>mod_http2</code> will only process one request at at time
+ per connection. But clients, such as browsers, will send many requests at the same time.
+ If one of these takes long to process (or is a long polling one), the other requests will
+ stall.</p>
+ <p><code>mod_http2</code> will not work around this limit by default. The reason is that
+ <code>prefork</code> is today only chosen, if you run processing engines that re not
+ prepared for multi-threading, e.g. will crash with more than one request.</p>
+ <p>If your setup can handle it, configuring <code>event</code> mpm is nowadays
+ the best one (if supported on your platform).</p>
+ <p>If you are really stuck with <code>prefork</code> and want multiple requests,
+ you can tweak the <directive module="mod_http2">H2MinWorkers</directive> to make
+ that possible. If it breaks, however, you own both parts.</p>
+ </section>
+
<section id="clients">
<title>Clients</title>
<p>Almost all modern browsers support HTTP/2, but only over SSL connections: Firefox (v43),