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Date: Wed, 03 Sep 2014 09:56:16 -0700
From: Mike Rumph <mike.rumph@oracle.com>
Organization: Oracle Corporation
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Subject: Re: [users@httpd] Understanding Apache Mutex directive.

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Hello dE,

I can only give you my own interpretation of this document.

First of all the Mutex directive in Apache httpd 2.4.x replaces several 
different directives from Apache httpd 2.2.x.
The SVN commit for this is 883540.
- http://svn.apache.org/viewvc?view=revision&revision=883540

The phrase "the first argument" in both cases probably means the first 
argument after the mechanism.
The doc should be worded more clearly.  (So this should probably changed 
to "the second argument".)

The mechanism is what kind of mutex technology is used.
Apache httpd uses several different mutexes for different purposes.
The mutex-name specifies which of these mutexes the Mutex directive 
applies to.
It is a little confusing that either one of these arguments can have the 
value "default".

So the phrase "The following mutex /mechanisms/ are available:" applies 
to the mechanism  (argument 1).
And the phrase "The following table documents" applies to the mutex-name 
(argument 2).

I hope this helps.

Thanks,

Mike Rumph

On 9/2/2014 10:10 PM, dE wrote:
> Hi.
>
> I was reading this --
>
> http://httpd.apache.org/docs/trunk/mod/core.html#mutex
>
> Quoting what's written here --
>> Specify |default| as the first argument to change the settings for 
>> all mutexes
> As we know mutex is a mechanism; it appears Apache has settings for 
> each mutex it implements.
>
>> specify a mutex name (see table below) as the first argument to 
>> override defaults only for that mutex.
>
> So the table starting with 'The following table documents....' lists 
> all the mechanisms. But before the table there exists a list with the 
> heading 'The following mutex mechanisms are available:'.
>
> So I don't understand which one of these is the mutex mechanism.
>
> Also the statement --
>
>> specify a mutex name (see table below) as the first argument to 
>> override defaults only for that mutex.
>
> Contradicts the examples --
>
>> Mutex  sysvsem default
>> Mutex  fcntl:/var/httpd/locks mpm-accept
>
> Where the entries in the table are not the first argument, instead the 
> list starting with 'The following mutex mechanisms are available:' is.
>
> Thanks for any clarification.


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    Hello dE,<br>
    <br>
    I can only give you my own interpretation of this document.<br>
    <br>
    First of all the Mutex directive in Apache httpd 2.4.x replaces
    several different directives from Apache httpd 2.2.x.<br>
    The SVN commit for this is 883540.<br>
    - <a class="moz-txt-link-freetext" href="http://svn.apache.org/viewvc?view=revision&amp;revision=883540">http://svn.apache.org/viewvc?view=revision&amp;revision=883540</a><br>
    <br>
    The phrase "the first argument" in both cases probably means the
    first argument after the mechanism.<br>
    The doc should be worded more clearly.&nbsp; (So this should probably
    changed to "the second argument".)<br>
    <br>
    The mechanism is what kind of mutex technology is used.<br>
    Apache httpd uses several different mutexes for different purposes.<br>
    The mutex-name specifies which of these mutexes the Mutex directive
    applies to.<br>
    It is a little confusing that either one of these arguments can have
    the value "default".<br>
    <br>
    So the phrase "The following mutex <em>mechanisms</em> are
    available:" applies to the mechanism&nbsp; (argument 1).<br>
    And the phrase "The following table documents" applies to the
    mutex-name (argument 2).<br>
    <br>
    I hope this helps.<br>
    <br>
    Thanks,<br>
    <br>
    Mike Rumph<br>
    <br>
    <div class="moz-cite-prefix">On 9/2/2014 10:10 PM, dE wrote:<br>
    </div>
    <blockquote cite="mid:5406A2BC.5050401@gmail.com" type="cite">
      <meta http-equiv="content-type" content="text/html;
        charset=ISO-8859-1">
      Hi.<br>
      <br>
      I was reading this -- <br>
      <br>
      <a moz-do-not-send="true" class="moz-txt-link-freetext"
        href="http://httpd.apache.org/docs/trunk/mod/core.html#mutex">http://httpd.apache.org/docs/trunk/mod/core.html#mutex</a><br>
      <br>
      Quoting what's written here -- <br>
      <blockquote type="cite">Specify <code>default</code> as the first
        argument to change the settings for all mutexes</blockquote>
      As we know mutex is a mechanism; it appears Apache has settings
      for each mutex it implements.<br>
      <br>
      <blockquote type="cite">specify a mutex name (see table below) as
        the first argument to override defaults only for that mutex.</blockquote>
      <br>
      So the table starting with 'The following table documents....'
      lists all the mechanisms. But before the table there exists a list
      with the heading 'The following mutex mechanisms are available:'.<br>
      <br>
      So I don't understand which one of these is the mutex mechanism.<br>
      <br>
      Also the statement -- <br>
      <br>
      <blockquote type="cite">specify a mutex name (see table below) as
        the first argument to override defaults only for that mutex.</blockquote>
      <br>
      Contradicts the examples -- <br>
      <br>
      <blockquote type="cite">
        <pre style="" class="prettyprint lang-config prettyprinted"><span class="kwd">Mutex</span><span class="pln"> sysvsem default
</span><span class="kwd">Mutex</span><span class="pln"> fcntl</span><span class="pun">:/</span><span class="pln">var</span><span class="pun">/</span><span class="pln">httpd</span><span class="pun">/</span><span class="pln">locks mpm-accept</span></pre>
      </blockquote>
      <br>
      Where the entries in the table are not the first argument, instead
      the list starting with 'The following mutex mechanisms are
      available:' is.<br>
      <br>
      Thanks for any clarification.<br>
    </blockquote>
    <br>
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