| <?xml version="1.0"?> |
| <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd"> |
| <?xml-stylesheet type="text/xsl" href="../style/manual.en.xsl"?> |
| <modulesynopsis> |
| |
| <name>mpm_common</name> |
| <description>A collection of directives that are implemented by |
| more than one multi-processing module (MPM)</description> |
| <status>MPM</status> |
| |
| <directivesynopsis> |
| <name>AcceptMutex</name> |
| <description>Method that Apache uses to serialize multiple children |
| accepting requests on network sockets</description> |
| <syntax>AcceptMutex Default|<var>method</var></syntax> |
| <default>AcceptMutex Default</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>perchild</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>The <directive>AcceptMutex</directive> directives sets the |
| method that Apache uses to serialize multiple children accepting |
| requests on network sockets. Prior to Apache 2.0, the method was |
| selectable only at compile time. The optimal method to use is |
| highly architecture and platform dependent. For further details, |
| see the <a href="../misc/perf-tuning.html">performance tuning</a> |
| documentation.</p> |
| |
| <p>If this directive is set to <code>Default</code>, then the |
| compile-time selected default will be used. Other possible |
| methods are listed below. Note that not all methods are |
| available on all platforms. If a method is specified which is |
| not available, a message will be written to the error log |
| listing the available methods.</p> |
| |
| <dl> |
| <dt><code>flock</code></dt> |
| <dd>uses the <code>flock(2)</code> system call to lock the |
| file defined by the <directive module="mpm_common" |
| >LockFile</directive> directive.</dd> |
| |
| <dt><code>fcntl</code></dt> |
| <dd>uses the <code>fnctl(2)</code> system call to lock the |
| file defined by the <directive module="mpm_common" |
| >LockFile</directive> directive.</dd> |
| |
| <dt><code>posixsem</code></dt> |
| <dd>uses POSIX compatible semaphores to implement the mutex.</dd> |
| |
| <dt><code>pthread</code></dt> |
| <dd>uses POSIX mutexes as implemented by the POSIX Threads |
| (PThreads) specification.</dd> |
| |
| <dt><code>sysvsem</code></dt> |
| <dd>uses SySV-style semaphores to implement the mutex.</dd> |
| </dl> |
| |
| <p>If you want to find out the compile time chosen default |
| for your system, you may set your <directive module="core" |
| >LogLevel</directive> to <code>debug</code>. Then the default <directive |
| >AcceptMutex</directive> will be written into the <directive |
| module="core">ErrorLog</directive>.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>BS2000Account</name> |
| <description>Define the non-privileged account on BS2000 |
| machines</description> |
| <syntax>BS2000Account <var>account</var></syntax> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>perchild</module><module>prefork</module></modulelist> |
| <compatibility>Only available for BS2000 machines</compatibility> |
| |
| <usage> |
| <p>The <directive>BS2000Account</directive> directive is available for |
| BS2000 hosts only. It must be used to define the account number for |
| the non-privileged apache server user (which was configured using the |
| <directive module="mpm_common">User</directive> directive). This is |
| required by the BS2000 POSIX subsystem (to change the underlying BS2000 |
| task environment by performing a sub-LOGON) to prevent CGI scripts |
| from accessing resources of the privileged account which started the |
| server, usually <code>SYSROOT</code>.</p> |
| |
| <note><title>Note</title> |
| <p>Only one <code>BS2000Account</code> directive can be used.</p> |
| </note> |
| </usage> |
| <seealso><a href="../platform/ebcdic.html">Apache EBCDIC port</a></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>CoreDumpDirectory</name> |
| <description>Directory where Apache attempts to |
| switch before dumping core</description> |
| <syntax>CoreDumpDirectory <var>directory</var></syntax> |
| <default>See usage for the default setting</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_winnt</module><module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>This controls the directory to which Apache attempts to |
| switch before dumping core. The default is in the |
| <directive module="core">ServerRoot</directive> directory, however |
| since this should not be writable by the user the server runs |
| as, core dumps won't normally get written. If you want a core |
| dump for debugging, you can use this directive to place it in a |
| different location.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>Group</name> |
| <description>Group under which the server will answer |
| requests</description> |
| <syntax>Group <var>unix-group</var></syntax> |
| <default>Group #-1</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpmt_os2</module><module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| <compatibility>Only valid in global server config since Apache |
| 2.0</compatibility> |
| |
| <usage> |
| <p>The <directive>Group</directive> directive sets the group under |
| which the server will answer requests. In order to use this |
| directive, the server must be run initially as root. If you start the |
| server as a non-root user, it will fail to change to the specified |
| group, and will instead continue to run as the group of the original |
| user. <var>Unix-group</var> is one of:</p> |
| |
| <dl> |
| <dt>A group name</dt> |
| <dd>Refers to the given group by name.</dd> |
| |
| <dt><code>#</code> followed by a group number.</dt> |
| <dd>Refers to a group by its number.</dd> |
| </dl> |
| |
| <example><title>Example</title> |
| Group www-group |
| </example> |
| |
| <p>It is recommended that you set up a new group specifically for |
| running the server. Some admins use user <code>nobody</code>, |
| but this is not always possible or desirable.</p> |
| |
| <note type="warning"><title>Security</title> |
| <p>Don't set <directive>Group</directive> (or <directive |
| module="mpm_common">User</directive>) to <code>root</code> unless |
| you know exactly what you are doing, and what the dangers are.</p> |
| </note> |
| |
| <p>Special note: Use of this directive in <directive module="core" |
| type="section">VirtualHost</directive> is no longer supported. To |
| configure your server for <a href="mod_suexec.html">suexec</a> use |
| <directive module="mod_suexec">SuexecUserGroup</directive>.</p> |
| |
| <note><title>Note</title> |
| <p>Although the <directive>Group</directive> directive is present |
| in the <module>beos</module> and <module>mpmt_os2</module> MPMs, |
| it is actually a no-op there and only exists for compatibility |
| reasons.</p> |
| </note> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>PidFile</name> |
| <description>File where the server records the process ID |
| of the daemon</description> |
| <syntax>PidFile <var>filename</var></syntax> |
| <default>PidFile logs/httpd.pid</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_winnt</module><module>mpmt_os2</module> |
| <module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>The <directive>PidFile</directive> 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 |
| <directive module="core">ServerRoot</directive>.</p> |
| |
| <example><title>Example</title> |
| PidFile /var/run/apache.pid |
| </example> |
| |
| <p>It is often useful to be able to send the server a signal, |
| so that it closes and then re-opens its <directive |
| module="core">ErrorLog</directive> and <directive |
| module="mod_log_config">TransferLog</directive>, and |
| re-reads its configuration files. This is done by sending a |
| SIGHUP (kill -1) signal to the process id listed in the |
| <directive>PidFile</directive>.</p> |
| |
| <p>The PidFile is subject to the same warnings about log file |
| placement and <a |
| href="../misc/security_tips.html#serverroot">security</a>.</p> |
| |
| <note><title>Note</title> |
| As of Apache 2 it is recommended to use only the <a |
| href="../programs/apachectl.html">apachectl</a> script for |
| (re-)starting or stopping the server. |
| </note> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>Listen</name> |
| <description>IP addresses and ports that the server |
| listens to</description> |
| <syntax>Listen [<var>IP-address</var>:]<var>portnumber</var></syntax> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>mpm_winnt</module> |
| <module>mpmt_os2</module><module>perchild</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| <compatibility>Required directive since Apache 2.0</compatibility> |
| |
| <usage> |
| <p>The <directive>Listen</directive> directive instructs Apache to |
| listen to only specific IP addresses or ports; by default it |
| responds to requests on all IP interfaces. <directive>Listen</directive> |
| is now a required directive. If it is not in the config file, the |
| server will fail to start. This is a change from previous versions |
| of Apache.</p> |
| |
| <p>The <directive>Listen</directive> directive tells the server to |
| accept incoming requests on the specified port or address-and-port |
| combination. If only a port number is specified, the server listens to |
| the given port on all interfaces. If an IP address is given as well |
| as a port, the server will listen on the given port and |
| interface.</p> |
| |
| <p>Multiple <directive>Listen</directive> directives may be used to |
| specify a number of addresses and ports to listen to. The server will |
| respond to requests from any of the listed addresses and ports.</p> |
| |
| <p>For example, to make the server accept connections on both |
| port 80 and port 8000, use:</p> |
| |
| <example> |
| Listen 80<br /> |
| Listen 8000 |
| </example> |
| |
| <p>To make the server accept connections on two specified |
| interfaces and port numbers, use </p> |
| |
| <example> |
| Listen 192.170.2.1:80<br /> |
| Listen 192.170.2.5:8000 |
| </example> |
| |
| <p>IPv6 addresses must be surrounded in square brackets, as in the |
| following example:</p> |
| |
| <example> |
| Listen [fe80::a00:20ff:fea7:ccea]:80 |
| </example> |
| </usage> |
| <seealso><a href="../dns-caveats.html">DNS Issues</a></seealso> |
| <seealso><a href="../bind.html">Setting which addresses and ports Apache |
| uses</a></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>ListenBackLog</name> |
| <description>Maximum length of the queue of pending connections</description> |
| <syntax>ListenBacklog <var>backlog</var></syntax> |
| <default>ListenBacklog 511</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>mpm_winnt</module> |
| <module>mpmt_os2</module><module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>The maximum length of the queue of pending connections. |
| Generally no tuning is needed or desired, however on some |
| systems it is desirable to increase this when under a TCP SYN |
| flood attack. See the backlog parameter to the |
| <code>listen(2)</code> system call.</p> |
| |
| <p>This will often be limited to a smaller number by the |
| operating system. This varies from OS to OS. Also note that |
| many OSes do not use exactly what is specified as the backlog, |
| but use a number based on (but normally larger than) what is |
| set.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>LockFile</name> |
| <description>Location of the accept serialization lock file</description> |
| <syntax>LockFile <var>filename</var></syntax> |
| <default>LockFile logs/accept.lock</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>perchild</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>The <directive>LockFile</directive> directive sets the path to |
| the lockfile used when Apache is used with an <directive |
| module="mpm_common">AcceptMutex</directive> value of either |
| <code>fcntl</code> or <code>flock</code>. This directive should |
| normally be left at its default value. The main reason for changing |
| it is if the <code>logs</code> directory is NFS mounted, since |
| <strong>the lockfile must be stored on a local disk</strong>. The PID |
| of the main server process is automatically appended to the |
| filename.</p> |
| |
| <note type="warning"><title>Security:</title> |
| <p>It is best to <em>avoid</em> putting this file in a world writable |
| directory such as <code>/var/tmp</code> because someone could create |
| a denial of service attack and prevent the server from starting by |
| creating a lockfile with the same name as the one the server will try |
| to create.</p> |
| </note> |
| </usage> |
| <seealso><directive module="mpm_common">AcceptMutex</directive></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>MaxClients</name> |
| <description>Maximum number of child processes that will be created |
| to serve requests</description> |
| <syntax>MaxClients <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>The <directive>MaxClients</directive> directive sets the limit |
| on the number of simultaneous requests that will be served. Any |
| connection attempts over the <directive>MaxClients</directive> |
| limit will normally be queued, up to a number based on the |
| <directive module="mpm_common">ListenBacklog</directive> |
| directive. Once a child process is freed at the end of a different |
| request, the connection will then be serviced.</p> |
| |
| <p>For non-threaded servers (<em>i.e.</em>, <module>prefork</module>), |
| <directive>MaxClients</directive> translates into the maximum |
| number of child processes that will be launched to serve requests. |
| The default value is 256; to increase it, you must also raise |
| <directive module="mpm_common">ServerLimit</directive>.</p> |
| |
| <p>For threaded and hybrid servers (<em>e.g.</em> <module>beos</module> |
| or <module>worker</module>) <directive>MaxClients</directive> restricts |
| the total number of threads that will be available to serve clients. |
| The default value for <module>beos</module> is <code>50</code>. For |
| hybrid MPMs the default value is <code>16</code> (<directive |
| module="mpm_common">ServerLimit</directive>) multiplied by the value of |
| <code>25</code> (<directive module="mpm_common" |
| >ThreadsPerChild</directive>). Therefore, to increase <directive |
| >MaxClients</directive> to a value that requires more than 16 processes, |
| you must also raise <directive module="mpm_common" |
| >ServerLimit</directive>.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>MaxMemFree</name> |
| <description>Maximum amount of memory that the main allocator is allowed |
| to hold without calling <code>free()</code></description> |
| <syntax>MaxMemFree <var>KBytes</var></syntax> |
| <default>MaxMemFree 0</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>The <directive>MaxMemFree</directive> directive sets the |
| maximum number of free Kbytes that the main allocator is allowed |
| to hold without calling <code>free()</code>. When not set, or when set |
| to zero, the threshold will be set to unlimited.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>MaxRequestsPerChild</name> |
| <description>Limit on the number of requests that an individual child server |
| will handle during its life</description> |
| <syntax>MaxRequestsPerChild <var>number</var></syntax> |
| <default>MaxRequestsPerChild 10000</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>mpm_netware</module> |
| <module>mpm_winnt</module><module>mpmt_os2</module> |
| <module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>The <directive>MaxRequestsPerChild</directive> directive sets |
| the limit on the number of requests that an individual child |
| server process will handle. After |
| <directive>MaxRequestsPerChild</directive> requests, the child |
| process will die. If <directive>MaxRequestsPerChild</directive> is |
| <code>0</code>, then the process will never expire.</p> |
| |
| <note><title>Different default values:</title> |
| <p>The default value for <module>mpm_netware</module> and |
| <module>mpm_winnt</module> is <code>0</code>.</p> |
| </note> |
| |
| <p>Setting <directive>MaxRequestsPerChild</directive> to a |
| non-zero limit has two beneficial effects:</p> |
| |
| <ul> |
| <li>it limits the amount of memory that process can consume |
| by (accidental) memory leakage;</li> |
| |
| <li>by giving processes a finite lifetime, it helps reduce |
| the number of processes when the server load reduces.</li> |
| </ul> |
| |
| <note><title>Note:</title> |
| <p>For <directive module="core">KeepAlive</directive> requests, only |
| the first request is counted towards this limit. In effect, it |
| changes the behavior to limit the number of <em>connections</em> per |
| child.</p> |
| </note> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>MaxSpareThreads</name> |
| <description>Maximum number of idle threads</description> |
| <syntax>MaxSpareThreads <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>mpmt_os2</module> |
| <module>perchild</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>Maximum number of idle threads. Different MPMs deal with this |
| directive differently.</p> |
| |
| <p>For <module>perchild</module> the default is |
| <code>MaxSpareThreads 10</code>. This MPM monitors the number of |
| idle threads on a per-child basis. If there are too many idle |
| threads in that child, the server will begin to kill threads |
| within that child.</p> |
| |
| <p>For <module>worker</module>, <module>leader</module> and <module |
| >threadpool</module> the default is <code>MaxSpareThreads 250</code>. |
| These MPMs deal with idle threads on a server-wide basis. If there |
| are too many idle threads in the server then child processes are |
| killed until the number of idle threads is less than this number.</p> |
| |
| <p>For <module>mpm_netware</module> the default is |
| <code>MaxSpareThreads 100</code>. Since this MPM runs a |
| single-process, the spare thread count is also server-wide.</p> |
| |
| <p><module>beos</module> and <module>mpmt_os2</module> work |
| similar to <module>mpm_netware</module>. The default for |
| <module>beos</module> is <code>MaxSpareThreads 50</code>. For |
| <module>mpmt_os2</module> the default value is <code>10</code>.</p> |
| |
| <note><title>Restrictions</title> |
| <p>The range of the <directive>MaxSpareThreads</directive> value |
| is restricted. Apache will correct the given value automatically |
| according to the following rules:</p> |
| <ul> |
| <li><module>perchild</module> requires <directive |
| >MaxSpareThreads</directive> to be less or equal than <directive |
| module="mpm_common">ThreadLimit</directive>.</li> |
| |
| <li><module>mpm_netware</module> wants the value to be greater than |
| <directive module="mpm_common">MinSpareThreads</directive>.</li> |
| |
| <li>For <module>leader</module>, <module>threadpool</module> and |
| <module>worker</module> the value must be greater or equal than |
| the sum of <directive module="mpm_common">MinSpareThreads</directive> |
| and <directive module="mpm_common">ThreadsPerChild</directive>.</li> |
| </ul> |
| </note> |
| </usage> |
| <seealso><directive module="mpm_common">MinSpareThreads</directive></seealso> |
| <seealso><directive module="mpm_common">StartServers</directive></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>MinSpareThreads</name> |
| <description>Minimum number of idle threads available to handle request |
| spikes</description> |
| <syntax>MinSpareThreads <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>mpmt_os2</module> |
| <module>perchild</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>Minimum number of idle threads to handle request spikes. |
| Different MPMs deal with this directive |
| differently.</p> |
| |
| <p><module>perchild</module> 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 <directive module="perchild" |
| >NumServers</directive> to <code>10</code> and a <directive |
| >MinSpareThreads</directive> value of <code>5</code>, you'll have |
| at least 50 idle threads on your system.</p> |
| |
| <p><module>worker</module>, <module>leader</module> and |
| <module>threadpool</module> 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><module>mpm_netware</module> 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><module>beos</module> and <module>mpmt_os2</module> work |
| similar to <module>mpm_netware</module>. The default for |
| <module>beos</module> is <code>MinSpareThreads 1</code>. For |
| <module>mpmt_os2</module> the default value is <code>5</code>.</p> |
| </usage> |
| <seealso><directive module="mpm_common">MaxSpareThreads</directive></seealso> |
| <seealso><directive module="mpm_common">StartServers</directive></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>ScoreBoardFile</name> |
| <description>Location of the file used to store coordination data for |
| the child processes</description> |
| <syntax>ScoreBoardFile <var>file-path</var></syntax> |
| <default>ScoreBoardFile logs/apache_status</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_winnt</module><module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <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> |
| |
| <example><title>Example</title> |
| ScoreBoardFile /var/run/apache_status |
| </example> |
| |
| <p>File-based shared memory is useful for third-party applications |
| that require direct access to the scoreboard.</p> |
| |
| <p>If you use a <directive>ScoreBoardFile</directive> 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> |
| </usage> |
| <seealso><a href="../stopping.html">Stopping and Restarting |
| Apache</a></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>SendBufferSize</name> |
| <description>TCP buffer size</description> |
| <syntax>SendBufferSize <var>bytes</var></syntax> |
| <default>SendBufferSize 0</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>leader</module> |
| <module>mpm_netware</module><module>mpm_winnt</module> |
| <module>mpmt_os2</module><module>perchild</module><module>prefork</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <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> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>ServerLimit</name> |
| <description>Upper limit on configurable number of processes</description> |
| <syntax>ServerLimit <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>perchild</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>For the <module>prefork</module> MPM, this directive sets the |
| maximum configured value for <directive |
| module="mpm_common">MaxClients</directive> for the lifetime of the |
| Apache process. For the worker MPM, this directive in combination |
| with <directive module="mpm_common">ThreadLimit</directive> sets |
| the maximum configured value for <directive |
| module="mpm_common">MaxClients</directive> for the lifetime of the |
| Apache process. Any attempts to change this directive during a |
| restart will be ignored, but <directive |
| module="mpm_common">MaxClients</directive> can be modified during |
| a restart.</p> |
| |
| <p>Special care must be taken when using this directive. If |
| <directive>ServerLimit</directive> is set to a value much higher |
| than necessary, extra, unused shared memory will be allocated. If |
| both <directive>ServerLimit</directive> and <directive |
| module="mpm_common">MaxClients</directive> are set to values |
| higher than the system can handle, Apache may not start or the |
| system may become unstable.</p> |
| |
| <p>With the <module>prefork</module> MPM, use this directive only |
| if you need to set <directive |
| module="mpm_common">MaxClients</directive> higher than 256 (default). |
| Do not set the value of this directive any higher than what you |
| might want to set <directive |
| module="mpm_common">MaxClients</directive> to.</p> |
| |
| <p>With <module>worker</module>, <module>leader</module> and |
| <module>threadpool</module> use this directive only |
| if your <directive module="mpm_common">MaxClients</directive> and |
| <directive module="mpm_common">ThreadsPerChild</directive> |
| 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 <directive |
| module="mpm_common">MaxClients </directive> and <directive |
| module="mpm_common">ThreadsPerChild</directive>.</p> |
| |
| <p>With the <module>perchild</module> MPM, use this directive only |
| if you need to set <directive |
| module="perchild">NumServers</directive> higher than 8 (default).</p> |
| |
| <note><title>Note</title> |
| <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> |
| </note> |
| </usage> |
| <seealso><a href="../stopping.html">Stopping and Restarting Apache</a></seealso> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>StartServers</name> |
| <description>Number of child server processes created at startup</description> |
| <syntax>StartServers <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>mpmt_os2</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| |
| <usage> |
| <p>The <directive>StartServers</directive> directive sets the |
| number of child server processes created on startup. As the number |
| of processes is dynamically controlled depending on the load, |
| there is usually little reason to adjust this parameter.</p> |
| |
| <p>The default value differs from MPM to MPM. For |
| <module>leader</module>, <module>threadpool</module> and |
| <module>worker</module> the default is <code>StartServers 3</code>. |
| For <module>prefork</module> defaults to <code>5</code> and for |
| <module>mpmt_os2</module> to <code>2</code>.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>StartThreads</name> |
| <description>Number of threads created on startup</description> |
| <syntax>StartThreads <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>beos</module><module>mpm_netware</module> |
| <module>perchild</module></modulelist> |
| |
| <usage> |
| <p>Number of threads created on startup. As the |
| number of threads is dynamically controlled depending on the |
| load, there is usually little reason to adjust this |
| parameter.</p> |
| |
| <p>For <module>perchild</module> the default is <code>StartThreads |
| 5</code> and this directive tracks the number of threads per |
| process at startup.</p> |
| |
| <p>For <module>mpm_netware</module> the default is |
| <code>StartThreads 50</code> and, since there is only a single |
| process, this is the total number of threads created at startup to |
| serve requests.</p> |
| |
| <p>For <module>beos</module> the default is <code>StartThreads |
| 10</code>. It also reflects the total number of threads created |
| at startup to serve requests.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>ThreadLimit</name> |
| <description>Sets the upper limit on the configurable number of threads |
| per child process</description> |
| <syntax>ThreadLimit <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>mpm_winnt</module> |
| <module>perchild</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| <compatibility>Available for <module>mpm_winnt</module> in Apache 2.0.41 |
| and later</compatibility> |
| |
| <usage> |
| <p>This directive sets the maximum configured value for <directive |
| module="mpm_common">ThreadsPerChild</directive> for the lifetime |
| of the Apache process. Any attempts to change this directive |
| during a restart will be ignored, but <directive |
| module="mpm_common">ThreadsPerChild</directive> can be modified |
| during a restart up to the value of this directive.</p> |
| |
| <p>Special care must be taken when using this directive. If |
| <directive>ThreadLimit</directive> is set to a value much higher |
| than <directive module="mpm_common">ThreadsPerChild</directive>, |
| extra unused shared memory will be allocated. If both |
| <directive>ThreadLimit</directive> and <directive |
| module="mpm_common">ThreadsPerChild</directive> are set to values |
| higher than the system can handle, Apache may not start or the |
| system may become unstable. Do not set the value of this directive |
| any higher than your greatest predicted setting of <directive |
| module="mpm_common">ThreadsPerChild</directive> for the |
| current run of Apache.</p> |
| |
| <p>The default value for <directive>ThreadLimit</directive> is |
| <code>1920</code> when used with <module>mpm_winnt</module> and |
| <code>64</code> when used with the others.</p> |
| |
| <note><title>Note</title> |
| <p>There is a hard limit of <code>ThreadLimit 20000</code> (or |
| <code>ThreadLimit 15000</code> with <module>mpm_winnt</module>) |
| compiled into the server. This is intended to avoid nasty effects |
| caused by typos.</p> |
| </note> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>ThreadsPerChild</name> |
| <description>Number of threads created by each child process</description> |
| <syntax>ThreadsPerChild <var>number</var></syntax> |
| <default>See usage for details</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>mpm_winnt</module> |
| <module>threadpool</module><module>worker</module></modulelist> |
| |
| <usage> |
| <p>This directive sets the number of threads created by each |
| child process. The child creates these threads at startup and |
| never creates more. If using an MPM like <module>mpm_winnt</module>, |
| where there is only one child process, this number should be high |
| enough to handle the entire load of the server. If using an MPM |
| like <module>worker</module>, where there are multiple child processes, |
| the <em>total</em> number of threads should be high enough to handle |
| the common load on the server.</p> |
| |
| <p>The default value for <directive>ThreadsPerChild</directive> is |
| <code>64</code> when used with <module>mpm_winnt</module> and |
| <code>25</code> when used with the others.</p> |
| </usage> |
| </directivesynopsis> |
| |
| <directivesynopsis> |
| <name>User</name> |
| <description>The userid under which the server will answer |
| requests</description> |
| <syntax>User <var>unix-userid</var></syntax> |
| <default>User #-1</default> |
| <contextlist><context>server config</context></contextlist> |
| <modulelist><module>leader</module><module>perchild</module> |
| <module>prefork</module><module>threadpool</module><module>worker</module> |
| </modulelist> |
| <compatibility>Only valid in global server config since Apache |
| 2.0</compatibility> |
| |
| <usage> |
| <p>The <directive>User</directive> directive sets the user ID as |
| which the server will answer requests. In order to use this |
| directive, the server must be run initially as <code>root</code>. |
| If you start the server as a non-root user, it will fail to change |
| to the lesser privileged user, and will instead continue to run as |
| that original user. If you do start the server as <code>root</code>, |
| then it is normal for the parent process to remain running as root. |
| <var>Unix-userid</var> is one of:</p> |
| |
| <dl> |
| <dt>A username</dt> |
| <dd>Refers to the given user by name.</dd> |
| |
| <dt># followed by a user number.</dt> |
| <dd>Refers to a user by its number.</dd> |
| </dl> |
| |
| <p>The user should have no privileges that result in it being |
| able to access files that are not intended to be visible to the |
| outside world, and similarly, the user should not be able to |
| execute code that is not meant for HTTP requests. It is |
| recommended that you set up a new user and group specifically for |
| running the server. Some admins use user <code>nobody</code>, but |
| this is not always desirable, since the <code>nobody</code> user |
| can have other uses on the system.</p> |
| |
| <note type="warning"><title>Security</title> |
| <p>Don't set <directive>User</directive> (or <directive |
| module="mpm_common">Group</directive>) to <code>root</code> unless |
| you know exactly what you are doing, and what the dangers are.</p> |
| </note> |
| |
| <p>With the <module>perchild</module> MPM, which is intended to |
| server virtual hosts run under different user IDs, the |
| <directive>User</directive> directive defines the user ID for the |
| main server and the fallback for <directive type="section" |
| module="core">VirtualHost</directive> sections without an |
| <directive module="perchild">AssignUserID</directive> directive.</p> |
| |
| <p>Special note: Use of this directive in <directive module="core" |
| type="section">VirtualHost</directive> is no longer supported. To |
| configure your server for <a href="../suexec.html">suexec</a> use |
| <directive module="mod_suexec">SuexecUserGroup</directive>.</p> |
| |
| <note><title>Note</title> |
| <p>Although the <directive>User</directive> directive is present |
| in the <module>beos</module> and <module>mpmt_os2</module> MPMs, |
| it is actually a no-op there and only exists for compatibility |
| reasons.</p> |
| </note> |
| </usage> |
| </directivesynopsis> |
| |
| </modulesynopsis> |