<p>Modify those examples to match your <code class="directive"><a href="./mod/core.html#serverroot">ServerRoot</a></code> and <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> settings.</p>
<p>The <code>USR1</code> or <code>graceful</code> signal causes
the parent process to <em>advise</em> the children to exit after
their current request (or to exit immediately if they're not
serving anything). The parent re-reads its configuration files and
re-opens its log files. As each child dies off the parent replaces
it with a child from the new <em>generation</em> of the
configuration, which begins serving new requests immediately.</p>
<p>This code is designed to always respect the process control
directive of the MPMs, so the number of processes and threads
available to serve clients will be maintained at the appropriate
values throughout the restart process. Furthermore, it respects
<code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> in the
following manner: if after one second at least <code class="directive"><a href="./mod/mpm_common.html#startservers">StartServers</a></code> new children have not
been created, then create enough to pick up the slack. Hence the
code tries to maintain both the number of children appropriate for
the current load on the server, and respect your wishes with the
<p>The <code>WINCH</code> or <code>graceful-stop</code> signal causes
the parent process to <em>advise</em> the children to exit after
their current request (or to exit immediately if they're not
serving anything). The parent will then remove its <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> and cease listening on
all ports. The parent will continue to run, and monitor children
which are handling requests. Once all children have finalised
and exited or the timeout specified by the <code class="directive"><a href="./mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> has been
reached, the parent will also exit. If the timeout is reached,
any remaining children will be sent the <code>TERM</code> signal
to force them to exit.</p>
<p>A <code>TERM</code> signal will immediately terminate the
parent process and all children when in the "graceful" state. However
as the <code class="directive"><a href="./mod/mpm_common.html#pidfile">PidFile</a></code> will
have been removed, you will not be able to use
<code>apachectl</code> or <code>httpd</code> to send this signal.</p>
<div class="note"><p>The <code>graceful-stop</code> signal allows you to run multiple
identically configured instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> at the
same time. This is a powerful feature when performing graceful
upgrades of Apache, however it can also cause deadlocks and race
conditions with some configurations.</p>
<p>Care has been taken to ensure that on-disk files
such as the <code class="directive"><a href="./mod/core.html#lockfile">Lockfile</a></code> and <code class="directive"><a href="./mod/mod_cgid.html#scriptsock">ScriptSock</a></code> files contain the server
PID, and should coexist without problem. However, if a configuration
directive, third-party module or persistent CGI utilises any other on-disk
lock or state files, care should be taken to ensure that multiple running
instances of <code class="program"><a href="./programs/httpd.html">httpd</a></code> do not clobber each others files.</p>
<p>You should also be wary of other potential race conditions, such as
using <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> style piped logging. Multiple running
instances of <code class="program"><a href="./programs/rotatelogs.html">rotatelogs</a></code> attempting to rotate the same
logfiles at the same time may destroy each other's logfiles.</p></div>
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