<?xml version="1.0"?>
<!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
<?xml-stylesheet type="text/xsl" href="../style/manual.xsl"?>
<modulesynopsis>
<name>worker</name>
<description>Multi-Processing Module implementing a hybrid
    multi-threaded multi-process web server</description>
<status>MPM</status>
<sourcefile>worker.c</sourcefile>
<identifier>mpm_worker_module</identifier>

<summary>
    <p>This Multi-Processing Module (MPM) implements a hybrid
    multi-process multi-threaded server. Each process has a fixed
    number of threads. The server adjusts to handle load by
    increasing or decreasing the number of processes.</p>

    <p>A single control process is responsible for launching child
    processes. Each child process creates a fixed number of threads
    as specified in the <code>ThreadsPerChild</code> directive. The
    individual threads then listen for connections and serve them
    when they arrive.</p>

    <p>Apache always tries to maintain a pool of <em>spare</em> or
    idle server threads, which stand ready to serve incoming
    requests. In this way, clients do not need to wait for a new
    threads or processes to be created before their requests can be
    served. Apache assesses the total number of idle threads in all
    processes, and forks or kills processes to keep this number
    within the boundaries specified by <code>MinSpareThreads</code>
    and <code>MaxSpareThreads</code>. Since this process is very
    self-regulating, it is rarely necessary to modify these
    directives from their default values. The maximum number of
    clients that may be served simultaneously is determined by
    multiplying the maximum number of server processes that will be
    created (<code>MaxClients</code>) by the number of threads
    created in each process (<code>ThreadsPerChild</code>).</p>

    <p>While the parent process is usually started as root under
    Unix in order to bind to port 80, the child processes and
    threads are launched by Apache as a less-privileged user. The
    <code>User</code> and <code>Group</code> directives are used to
    set the privileges of the Apache child processes. The child
    processes must be able to read all the content that will be
    served, but should have as few privileges beyond that as
    possible. In addition, unless <a
    href="../suexec.html">suexec</a> is used, these directives also
    set the privileges which will be inherited by CGI scripts.</p>

    <p><code>MaxRequestsPerChild</code> controls how frequently the
    server recycles processes by killing old ones and launching new
    ones.</p>

    <p>See also: <a href="../bind.html">Setting which addresses and
    ports Apache uses</a>.</p>
</summary>

<directivesynopsis location="mpm_common"><name>CoreDumpDirectory</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>Group</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>PidFile</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>Listen</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>ListenBacklog</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>LockFile</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>MaxClients</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>MaxRequestsPerChild</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>MaxSpareThreads</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>MinSpareThreads</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>ScoreBoardFile</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>SendBufferSize</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>ServerLimit</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>StartServers</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>ThreadLimit</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>ThreadsPerChild</name>
</directivesynopsis>
<directivesynopsis location="mpm_common"><name>User</name>
</directivesynopsis>

</modulesynopsis>
