atom feed3 messages in org.apache.httpd.docsFwd: svn commit: r1395417 - in /httpd...
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Jeff TrawickOct 8, 2012 7:31 am 
Rich BowenOct 8, 2012 8:25 am 
Rich BowenOct 8, 2012 4:37 pm 
Subject:Fwd: svn commit: r1395417 - in /httpd/httpd/trunk/docs/manual: mpm.html.en mpm.xml
From:Jeff Trawick (traw@gmail.com)
Date:Oct 8, 2012 7:31:57 am
List:org.apache.httpd.docs

---------- Forwarded message ---------- From: Jeff Trawick <traw@gmail.com> Date: Mon, Oct 8, 2012 at 8:34 AM Subject: Re: svn commit: r1395417 - in /httpd/httpd/trunk/docs/manual: mpm.html.en mpm.xml To: de@httpd.apache.org

On Sun, Oct 7, 2012 at 6:59 PM, <rbo@apache.org> wrote:

Author: rbowen Date: Sun Oct 7 22:59:14 2012 New Revision: 1395417

URL: http://svn.apache.org/viewvc?rev=1395417&view=rev Log: Adds some clarification to the statement that the default MPM is selected based on platform capabilities.

Modified: httpd/httpd/trunk/docs/manual/mpm.html.en httpd/httpd/trunk/docs/manual/mpm.xml

Modified: httpd/httpd/trunk/docs/manual/mpm.html.en URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/mpm.html.en?rev=1395417&r1=1395416&r2=1395417&view=diff ============================================================================== --- httpd/httpd/trunk/docs/manual/mpm.html.en (original) +++ httpd/httpd/trunk/docs/manual/mpm.html.en Sun Oct 7 22:59:14 2012 @@ -99,6 +99,28 @@ choice at compile-time.</p> <code class="module"><a href="./mod/event.html">event</a></code>, depending
on platform capabilities</td></tr> <tr class="odd"><td>Windows</td><td><code class="module"><a
href="./mod/mpm_winnt.html">mpm_winnt</a></code></td></tr> </table> + +<div class="note"><p>Here, 'Unix' is used to mean Unix-like operating systems,
such as +Linux, BSD, Solaris, Mac OS X, etc.</p></div> + +<p>In the case of Unix, the decision as to which MPM is installed is +based on two questions:</p> +<p>1. Does the system support <a
href="http://en.wikipedia.org/wiki/Threads_(computer_science)">threads</a>?</p> +<p>2. Does the system support <a
href="http://en.wikipedia.org/wiki/Polling_(computer_science)">polling</a>?</p> + +<p>If the answer to both questions is 'yes', the default MPM is +<code class="module"><a href="./mod/event.html">event</a></code>.</p>

It isn't that simple.

APR_POLLSET_THREADSAFE has to be supported, and that is more than the well-known capabilities of threads and polling.

APR_POLLSET_THREADSAFE means that the platform has an advanced polling mechanism which allows pollsets to be manipulated in a certain way, and that APR has an implementation that uses that mechanism.

Linux, Solaris, and FreeBSD/Mac OS X are platforms that satisify both characteristics. z/OS is a platform that has an advanced polling mechanism but without an APR implementation in the stable branches. Neither AIX nor HP-UX have APR implementations, though I'd guess that the OS has the feature and nobody has gotten around to exploiting it in APR.

+ +<p>If The answer to #1 is 'yes', but the answer to #2 is 'no', the +default will be <code class="module"><a
href="./mod/worker.html">worker</a></code>.</p> + +<p>If the answer to both questions is 'no', then the default MPM will be +<code class="module"><a href="./mod/prefork.html">prefork</a></code>.</p> + +<p>In practical terms, this means that the default will almost always be +<code class="module"><a href="./mod/event.html">event</a></code>, as all modern
operating systems support these +two features.</p> + </div><div class="top"><a href="#page-header"><img alt="top"
src="./images/up.gif" /></a></div> <div class="section"> <h2><a name="static" id="static">Building an MPM as a static module</a></h2>

Modified: httpd/httpd/trunk/docs/manual/mpm.xml URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/mpm.xml?rev=1395417&r1=1395416&r2=1395417&view=diff ============================================================================== --- httpd/httpd/trunk/docs/manual/mpm.xml (original) +++ httpd/httpd/trunk/docs/manual/mpm.xml Sun Oct 7 22:59:14 2012 @@ -89,6 +89,30 @@ choice at compile-time.</p> <module>event</module>, depending on platform capabilities</td></tr> <tr><td>Windows</td><td><module>mpm_winnt</module></td></tr> </table> + +<note><p>Here, 'Unix' is used to mean Unix-like operating systems, such as +Linux, BSD, Solaris, Mac OS X, etc.</p></note> + +<p>In the case of Unix, the decision as to which MPM is installed is +based on two questions:</p> +<p>1. Does the system support <a +href="http://en.wikipedia.org/wiki/Threads_(computer_science)">threads</a>?</p> +<p>2. Does the system support <a +href="http://en.wikipedia.org/wiki/Polling_(computer_science)">polling</a>?</p> + +<p>If the answer to both questions is 'yes', the default MPM is +<module>event</module>.</p> + +<p>If The answer to #1 is 'yes', but the answer to #2 is 'no', the +default will be <module>worker</module>.</p> + +<p>If the answer to both questions is 'no', then the default MPM will be +<module>prefork</module>.</p> + +<p>In practical terms, this means that the default will almost always be +<module>event</module>, as all modern operating systems support these +two features.</p> + </section>

<section id="static"><title>Building an MPM as a static module</title>