mpm_common.html.en

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

</table>
    <p>Minimum number of idle threads to handle request spikes.
    Different MPMs deal with this directive
    differently.</p>

    <p><code class="module"><a href="../mod/perchild.html">perchild</a></code> uses a default of
    <code>MinSpareThreads 5</code> and monitors the number of idle
    threads on a per-child basis. If there aren't enough idle threads
    in that child, the server will begin to create new threads within
    that child. Thus, if you set <code class="directive"><a href="../mod/perchild.html#numservers">NumServers</a></code> to <code>10</code> and a <code class="directive">MinSpareThreads</code> value of <code>5</code>, you'll have
    at least 50 idle threads on your system.</p>

    <p><code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/leader.html">leader</a></code> and
    <code class="module"><a href="../mod/threadpool.html">threadpool</a></code> use a default of <code>MinSpareThreads
    75</code> and deal with idle threads on a server-wide basis. If
    there aren't enough idle threads in the server then child
    processes are created until the number of idle threads is greater
    than number.</p>

    <p><code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code> uses a default of
    <code>MinSpareThreads 10</code> and, since it is a single-process
    MPM, tracks this on a server-wide bases.</p>

    <p><code class="module"><a href="../mod/beos.html">beos</a></code> and <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> work
    similar to <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>. The default for
    <code class="module"><a href="../mod/beos.html">beos</a></code> is <code>MinSpareThreads 1</code>. For
    <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code> the default value is <code>5</code>.</p>

<h3>See also</h3>
<ul>
<li><code class="directive"><a href="#maxsparethreads">MaxSpareThreads</a></code></li>
<li><code class="directive"><a href="#startservers">StartServers</a></code></li>
</ul>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="PidFile" id="PidFile">PidFile</a> <a name="pidfile" id="pidfile">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>File where the server records the process ID
of the daemon</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>PidFile <var>filename</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>PidFile logs/httpd.pid</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/beos.html">beos</a></code>, <code class="module"><a href="../mod/leader.html">leader</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code>, <code class="module"><a href="../mod/perchild.html">perchild</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/threadpool.html">threadpool</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code></td></tr>
</table>
    <p>The <code class="directive">PidFile</code> directive sets the file to
    which the server records the process id of the daemon. If the
    filename is not absolute then it is assumed to be relative to the
    <code class="directive"><a href="../mod/core.html#serverroot">ServerRoot</a></code>.</p>

    <div class="example"><h3>Example</h3><p><code>
      PidFile /var/run/apache.pid
    </code></p></div>

    <p>It is often useful to be able to send the server a signal,
    so that it closes and then re-opens its <code class="directive"><a href="../mod/core.html#errorlog">ErrorLog</a></code> and <code class="directive"><a href="../mod/mod_log_config.html#transferlog">TransferLog</a></code>, and
    re-reads its configuration files. This is done by sending a
    SIGHUP (kill -1) signal to the process id listed in the
    <code class="directive">PidFile</code>.</p>

    <p>The <code class="directive">PidFile</code> is subject to the same
    warnings about log file placement and <a href="../misc/security_tips.html#serverroot">security</a>.</p>

    <div class="note"><h3>Note</h3>
      <p>As of Apache 2 it is recommended to use only the <code class="program"><a href="../programs/apachectl.html">apachectl</a></code> script for (re-)starting or stopping the server.</p>
    </div>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="ScoreBoardFile" id="ScoreBoardFile">ScoreBoardFile</a> <a name="scoreboardfile" id="scoreboardfile">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Location of the file used to store coordination data for
the child processes</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ScoreBoardFile <var>file-path</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ScoreBoardFile logs/apache_status</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/beos.html">beos</a></code>, <code class="module"><a href="../mod/leader.html">leader</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/perchild.html">perchild</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/threadpool.html">threadpool</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code></td></tr>
</table>
    <p>Apache uses a scoreboard to communicate between its parent
    and child processes.  Some architectures require a file to facilitate
    this communication. If the file is left unspecified, Apache first
    attempts to create the scoreboard entirely in memory (using anonymous
    shared memory) and, failing that, will attempt to create the file on
    disk (using file-based shared memory). Specifying this directive causes
    Apache to always create the file on the disk.</p>

    <div class="example"><h3>Example</h3><p><code>
      ScoreBoardFile /var/run/apache_status
    </code></p></div>

    <p>File-based shared memory is useful for third-party applications
    that require direct access to the scoreboard.</p>

    <p>If you use a <code class="directive">ScoreBoardFile</code> then
    you may see improved speed by placing it on a RAM disk. But be
    careful that you heed the same warnings about log file placement
    and <a href="../misc/security_tips.html">security</a>.</p>

<h3>See also</h3>
<ul>
<li><a href="../stopping.html">Stopping and Restarting
Apache</a></li>
</ul>
</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="SendBufferSize" id="SendBufferSize">SendBufferSize</a> <a name="sendbuffersize" id="sendbuffersize">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>TCP buffer size</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>SendBufferSize <var>bytes</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>SendBufferSize 0</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/beos.html">beos</a></code>, <code class="module"><a href="../mod/leader.html">leader</a></code>, <code class="module"><a href="../mod/mpm_netware.html">mpm_netware</a></code>, <code class="module"><a href="../mod/mpm_winnt.html">mpm_winnt</a></code>, <code class="module"><a href="../mod/mpmt_os2.html">mpmt_os2</a></code>, <code class="module"><a href="../mod/perchild.html">perchild</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/threadpool.html">threadpool</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code></td></tr>
</table>
    <p>The server will set the TCP buffer size to the number of bytes
    specified. Very useful to increase past standard OS defaults on
    high speed high latency (<em>i.e.</em>, 100ms or so, such as
    transcontinental fast pipes).</p>

    <p>If set to the value of <code>0</code>, the server will use the
    OS deault.</p>

</div>
<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
<div class="directive-section"><h2><a name="ServerLimit" id="ServerLimit">ServerLimit</a> <a name="serverlimit" id="serverlimit">Directive</a></h2>
<table class="directive">
<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Upper limit on configurable number of processes</td></tr>
<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ServerLimit <var>number</var></code></td></tr>
<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>See usage for details</code></td></tr>
<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config</td></tr>
<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>MPM</td></tr>
<tr><th><a href="directive-dict.html#Module">Module:</a></th><td><code class="module"><a href="../mod/leader.html">leader</a></code>, <code class="module"><a href="../mod/perchild.html">perchild</a></code>, <code class="module"><a href="../mod/prefork.html">prefork</a></code>, <code class="module"><a href="../mod/threadpool.html">threadpool</a></code>, <code class="module"><a href="../mod/worker.html">worker</a></code></td></tr>
</table>
    <p>For the <code class="module"><a href="../mod/prefork.html">prefork</a></code> MPM, this directive sets the
    maximum configured value for <code class="directive"><a href="#maxclients">MaxClients</a></code> for the lifetime of the
    Apache process.  For the <code class="module"><a href="../mod/worker.html">worker</a></code> MPM, this directive
    in combination with <code class="directive"><a href="#threadlimit">ThreadLimit</a></code> sets
    the maximum configured value for <code class="directive"><a href="#maxclients">MaxClients</a></code> for the lifetime of the
    Apache process.  Any attempts to change this directive during a
    restart will be ignored, but <code class="directive"><a href="#maxclients">MaxClients</a></code> can be modified during
    a restart.</p>

    <p>Special care must be taken when using this directive.  If
    <code class="directive">ServerLimit</code> is set to a value much higher
    than necessary, extra, unused shared memory will be allocated.  If
    both <code class="directive">ServerLimit</code> and <code class="directive"><a href="#maxclients">MaxClients</a></code> are set to values
    higher than the system can handle, Apache may not start or the
    system may become unstable.</p>

    <p>With the <code class="module"><a href="../mod/prefork.html">prefork</a></code> MPM, use this directive only
    if you need to set <code class="directive"><a href="#maxclients">MaxClients</a></code> higher than 256 (default).
    Do not set the value of this directive any higher than what you
    might want to set <code class="directive"><a href="#maxclients">MaxClients</a></code> to.</p>

    <p>With <code class="module"><a href="../mod/worker.html">worker</a></code>, <code class="module"><a href="../mod/leader.html">leader</a></code> and
    <code class="module"><a href="../mod/threadpool.html">threadpool</a></code> use this directive only
    if your <code class="directive"><a href="#maxclients">MaxClients</a></code> and
    <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>
    settings require more than 16 server processes (default). Do not set
    the value of this directive any higher than the number of server
    processes required by what you may want for <code class="directive"><a href="#maxclients ">MaxClients </a></code> and <code class="directive"><a href="#threadsperchild">ThreadsPerChild</a></code>.</p>

    <p>With the <code class="module"><a href="../mod/perchild.html">perchild</a></code> MPM, use this directive only
    if you need to set <code class="directive"><a href="../mod/perchild.html#numservers">NumServers</a></code> higher than 8 (default).</p>

    <div class="note"><h3>Note</h3>
      <p>There is a hard limit of <code>ServerLimit 20000</code> compiled
      into the server. This is intended to avoid nasty effects caused by
      typos.</p>
    </div>

<h3>See also</h3>