From e8ec7aa8e38a93f5b034ac74cebce5de23710317 Mon Sep 17 00:00:00 2001 From: hongbotian Date: Mon, 30 Nov 2015 01:45:08 -0500 Subject: upload http JIRA: BOTTLENECK-10 Change-Id: I7598427ff904df438ce77c2819ee48ac75ffa8da Signed-off-by: hongbotian --- .../docs/manual/mod/mpm_common.html.en | 896 +++++++++++++++++++++ 1 file changed, 896 insertions(+) create mode 100644 rubbos/app/httpd-2.0.64/docs/manual/mod/mpm_common.html.en (limited to 'rubbos/app/httpd-2.0.64/docs/manual/mod/mpm_common.html.en') diff --git a/rubbos/app/httpd-2.0.64/docs/manual/mod/mpm_common.html.en b/rubbos/app/httpd-2.0.64/docs/manual/mod/mpm_common.html.en new file mode 100644 index 00000000..5b3bbc48 --- /dev/null +++ b/rubbos/app/httpd-2.0.64/docs/manual/mod/mpm_common.html.en @@ -0,0 +1,896 @@ + + + +mpm_common - Apache HTTP Server + + + + + +
+

Modules | Directives | FAQ | Glossary | Sitemap

+

Apache HTTP Server Version 2.0

+
+
<-
+ +
+

Apache MPM Common Directives

+
+

Available Languages:  de  | + en  | + es  | + ja  | + tr 

+
+ +
Description:A collection of directives that are implemented by +more than one multi-processing module (MPM)
Status:MPM
+
+ + +
top
+

AcceptMutex Directive

+ + + + + + + +
Description:Method that Apache uses to serialize multiple children +accepting requests on network sockets
Syntax:AcceptMutex Default|method
Default:AcceptMutex Default
Context:server config
Status:MPM
Module:leader, perchild, prefork, threadpool, worker
+

The AcceptMutex 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 performance tuning + documentation.

+ +

If this directive is set to Default, 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.

+ +
+
flock
+
uses the flock(2) system call to lock the + file defined by the LockFile directive.
+ +
fcntl
+
uses the fcntl(2) system call to lock the + file defined by the LockFile directive.
+ +
posixsem
+
uses POSIX compatible semaphores to implement the mutex.
+ +
pthread
+
uses POSIX mutexes as implemented by the POSIX Threads + (PThreads) specification.
+ +
sysvsem
+
uses SySV-style semaphores to implement the mutex.
+
+ +

If you want to find out the compile time chosen default + for your system, you may set your LogLevel to debug. Then the default AcceptMutex will be written into the ErrorLog.

+ +
+
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+

BS2000Account Directive

+ + + + + + + +
Description:Define the non-privileged account on BS2000 +machines
Syntax:BS2000Account account
Context:server config
Status:MPM
Module:perchild, prefork
Compatibility:Only available for BS2000 machines
+

The BS2000Account 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 + User 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 SYSROOT.

+ +

Note

+

Only one BS2000Account directive can be used.

+
+ +

See also

+ +
+
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+

CoreDumpDirectory Directive

+ + + + + + + +
Description:Directory where Apache attempts to +switch before dumping core
Syntax:CoreDumpDirectory directory
Default:See usage for the default setting
Context:server config
Status:MPM
Module:beos, leader, mpm_winnt, perchild, prefork, threadpool, worker
+

This controls the directory to which Apache attempts to + switch before dumping core. The default is in the + ServerRoot 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.

+ +

Core Dumps on Linux

+

If Apache starts as root and switches to another user, the + Linux kernel disables core dumps even if the directory is + writable for the process. Apache (2.0.46 and later) reenables core dumps + on Linux 2.4 and beyond, but only if you explicitly configure a CoreDumpDirectory.

+
+ +
+
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+

EnableExceptionHook Directive

+ + + + + + + + +
Description:Enables a hook that runs exception handlers +after a crash
Syntax:EnableExceptionHook On|Off
Default:EnableExceptionHook Off
Context:server config
Status:MPM
Module:leader, perchild, prefork, threadpool, worker
Compatibility:Available in version 2.0.49 and later
+

For safety reasons this directive is only available if the server was + configured with the --enable-exception-hook option. It + enables a hook that allows external modules to plug in and do something + after a child crashed.

+ +

There are already two modules, mod_whatkilledus and + mod_backtrace that make use of this hook. Please have a + look at Jeff Trawick's EnableExceptionHook site for more information about these.

+ +
+
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+

Group Directive

+ + + + + + + + +
Description:Group under which the server will answer +requests
Syntax:Group unix-group
Default:Group #-1
Context:server config
Status:MPM
Module:beos, leader, mpmt_os2, perchild, prefork, threadpool, worker
Compatibility:Only valid in global server config since Apache +2.0
+

The Group 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. Unix-group is one of:

+ +
+
A group name
+
Refers to the given group by name.
+ +
# followed by a group number.
+
Refers to a group by its number.
+
+ +

Example

+ Group www-group +

+ +

It is recommended that you set up a new group specifically for + running the server. Some admins use user nobody, + but this is not always possible or desirable.

+ +

Security

+

Don't set Group (or User) to root unless + you know exactly what you are doing, and what the dangers are.

+
+ +

Special note: Use of this directive in <VirtualHost> is no longer supported. To + configure your server for suexec use + SuexecUserGroup.

+ +

Note

+

Although the Group directive is present + in the beos and mpmt_os2 MPMs, + it is actually a no-op there and only exists for compatibility + reasons.

+
+ +
+
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+

Listen Directive

+ + + + + + + +
Description:IP addresses and ports that the server +listens to
Syntax:Listen [IP-address:]portnumber
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
Compatibility:Required directive since Apache 2.0
+

The Listen directive instructs Apache to + listen to only specific IP addresses or ports; by default it + responds to requests on all IP interfaces. Listen + 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.

+ +

The Listen 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.

+ +

Multiple Listen 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.

+ +

For example, to make the server accept connections on both + port 80 and port 8000, use:

+ +

+ Listen 80
+ Listen 8000 +

+ +

To make the server accept connections on two specified + interfaces and port numbers, use

+ +

+ Listen 192.170.2.1:80
+ Listen 192.170.2.5:8000 +

+ +

IPv6 addresses must be surrounded in square brackets, as in the + following example:

+ +

+ Listen [2001:db8::a00:20ff:fea7:ccea]:80 +

+ +

Error condition

+ Multiple Listen directives for the same ip + address and port will result in an Address already in use + error message. +
+ +

See also

+ +
+
top
+

ListenBackLog Directive

+ + + + + + + +
Description:Maximum length of the queue of pending connections
Syntax:ListenBacklog backlog
Default:ListenBacklog 511
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
+

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 + listen(2) system call.

+ +

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.

+ +
+
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+

LockFile Directive

+ + + + + + + +
Description:Location of the accept serialization lock file
Syntax:LockFile filename
Default:LockFile logs/accept.lock
Context:server config
Status:MPM
Module:leader, perchild, prefork, threadpool, worker
+

The LockFile directive sets the path to + the lockfile used when Apache is used with an AcceptMutex value of either + fcntl or flock. This directive should + normally be left at its default value. The main reason for changing + it is if the logs directory is NFS mounted, since + the lockfile must be stored on a local disk. The PID + of the main server process is automatically appended to the + filename.

+ +

Security

+

It is best to avoid putting this file in a world writable + directory such as /var/tmp 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.

+
+ +

See also

+ +
+
top
+

MaxClients Directive

+ + + + + + + +
Description:Maximum number of connections that will be processed +simultaneously
Syntax:MaxClients number
Default:See usage for details
Context:server config
Status:MPM
Module:beos, leader, prefork, threadpool, worker
+

The MaxClients directive sets the limit + on the number of simultaneous requests that will be served. Any + connection attempts over the MaxClients + limit will normally be queued, up to a number based on the + ListenBacklog + directive. Once a child process is freed at the end of a different + request, the connection will then be serviced.

+ +

For non-threaded servers (i.e., prefork), + MaxClients 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 + ServerLimit.

+ +

For threaded and hybrid servers (e.g. beos + or worker) MaxClients restricts + the total number of threads that will be available to serve clients. + The default value for beos is 50. For + hybrid MPMs the default value is 16 (ServerLimit) multiplied by the value of + 25 (ThreadsPerChild). Therefore, to increase MaxClients to a value that requires more than 16 processes, + you must also raise ServerLimit.

+ +
+
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+

MaxMemFree Directive

+ + + + + + + +
Description:Maximum amount of memory that the main allocator is allowed +to hold without calling free()
Syntax:MaxMemFree KBytes
Default:MaxMemFree 0
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, prefork, threadpool, worker, mpm_winnt
+

The MaxMemFree directive sets the + maximum number of free Kbytes that the main allocator is allowed + to hold without calling free(). When not set, or when set + to zero, the threshold will be set to unlimited.

+ +
+
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+

MaxRequestsPerChild Directive

+ + + + + + + +
Description:Limit on the number of requests that an individual child server +will handle during its life
Syntax:MaxRequestsPerChild number
Default:MaxRequestsPerChild 10000
Context:server config
Status:MPM
Module:leader, mpm_netware, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
+

The MaxRequestsPerChild directive sets + the limit on the number of requests that an individual child + server process will handle. After + MaxRequestsPerChild requests, the child + process will die. If MaxRequestsPerChild is + 0, then the process will never expire.

+ +

Different default values

+

The default value for mpm_netware and + mpm_winnt is 0.

+
+ +

Setting MaxRequestsPerChild to a + non-zero value limits the amount of memory that process can consume + by (accidental) memory leakage.

+ +

Note

+

For KeepAlive requests, only + the first request is counted towards this limit. In effect, it + changes the behavior to limit the number of connections per + child.

+
+ +
+
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+

MaxSpareThreads Directive

+ + + + + + + +
Description:Maximum number of idle threads
Syntax:MaxSpareThreads number
Default:See usage for details
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpmt_os2, perchild, threadpool, worker
+

Maximum number of idle threads. Different MPMs deal with this + directive differently.

+ +

For perchild the default is + MaxSpareThreads 10. 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.

+ +

For worker, leader and threadpool the default is MaxSpareThreads 250. + 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.

+ +

For mpm_netware the default is + MaxSpareThreads 100. Since this MPM runs a + single-process, the spare thread count is also server-wide.

+ +

beos and mpmt_os2 work + similar to mpm_netware. The default for + beos is MaxSpareThreads 50. For + mpmt_os2 the default value is 10.

+ +

Restrictions

+

The range of the MaxSpareThreads value + is restricted. Apache will correct the given value automatically + according to the following rules:

+ +
+ +

See also

+ +
+
top
+

MinSpareThreads Directive

+ + + + + + + +
Description:Minimum number of idle threads available to handle request +spikes
Syntax:MinSpareThreads number
Default:See usage for details
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpmt_os2, perchild, threadpool, worker
+

Minimum number of idle threads to handle request spikes. + Different MPMs deal with this directive + differently.

+ +

perchild uses a default of + MinSpareThreads 5 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 NumServers to 10 and a MinSpareThreads value of 5, you'll have + at least 50 idle threads on your system.

+ +

worker, leader and + threadpool use a default of MinSpareThreads + 75 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.

+ +

mpm_netware uses a default of + MinSpareThreads 10 and, since it is a single-process + MPM, tracks this on a server-wide bases.

+ +

beos and mpmt_os2 work + similar to mpm_netware. The default for + beos is MinSpareThreads 1. For + mpmt_os2 the default value is 5.

+ +

See also

+ +
+
top
+

PidFile Directive

+ + + + + + + +
Description:File where the server records the process ID +of the daemon
Syntax:PidFile filename
Default:PidFile logs/httpd.pid
Context:server config
Status:MPM
Module:beos, leader, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
+

The PidFile 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 + ServerRoot.

+ +

Example

+ PidFile /var/run/apache.pid +

+ +

It is often useful to be able to send the server a signal, + so that it closes and then re-opens its ErrorLog and TransferLog, and + re-reads its configuration files. This is done by sending a + SIGHUP (kill -1) signal to the process id listed in the + PidFile.

+ +

The PidFile is subject to the same + warnings about log file placement and security.

+ +

Note

+

As of Apache 2 it is recommended to use only the apachectl script for (re-)starting or stopping the server.

+
+ +
+
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+

ReceiveBufferSize Directive

+ + + + + + + +
Description:TCP receive buffer size
Syntax:ReceiveBufferSize bytes
Default:ReceiveBufferSize 0
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
+

The server will set the TCP receive buffer size to the number of + bytes specified.

+ +

If set to the value of 0, the server will use the + OS default.

+ +
+
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+

ScoreBoardFile Directive

+ + + + + + + +
Description:Location of the file used to store coordination data for +the child processes
Syntax:ScoreBoardFile file-path
Default:ScoreBoardFile logs/apache_status
Context:server config
Status:MPM
Module:beos, leader, mpm_winnt, perchild, prefork, threadpool, worker
+

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.

+ +

Example

+ ScoreBoardFile /var/run/apache_status +

+ +

File-based shared memory is useful for third-party applications + that require direct access to the scoreboard.

+ +

If you use a ScoreBoardFile 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 security.

+ +

See also

+ +
+
top
+

SendBufferSize Directive

+ + + + + + + +
Description:TCP buffer size
Syntax:SendBufferSize bytes
Default:SendBufferSize 0
Context:server config
Status:MPM
Module:beos, leader, mpm_netware, mpm_winnt, mpmt_os2, perchild, prefork, threadpool, worker
+

The server will set the TCP send buffer size to the number of bytes + specified. Very useful to increase past standard OS defaults on + high speed high latency (i.e., 100ms or so, such as + transcontinental fast pipes).

+ +

If set to the value of 0, the server will use the + OS default.

+ +
+
top
+

ServerLimit Directive

+ + + + + + + +
Description:Upper limit on configurable number of processes
Syntax:ServerLimit number
Default:See usage for details
Context:server config
Status:MPM
Module:leader, perchild, prefork, threadpool, worker
+

For the prefork MPM, this directive sets the + maximum configured value for MaxClients for the lifetime of the + Apache process. For the worker MPM, this directive + in combination with ThreadLimit sets + the maximum configured value for MaxClients for the lifetime of the + Apache process. Any attempts to change this directive during a + restart will be ignored, but MaxClients can be modified during + a restart.

+ +

Special care must be taken when using this directive. If + ServerLimit is set to a value much higher + than necessary, extra, unused shared memory will be allocated. If + both ServerLimit and MaxClients are set to values + higher than the system can handle, Apache may not start or the + system may become unstable.

+ +

With the prefork MPM, use this directive only + if you need to set MaxClients higher than 256 (default). + Do not set the value of this directive any higher than what you + might want to set MaxClients to.

+ +

With worker, leader and + threadpool use this directive only + if your MaxClients and + ThreadsPerChild + 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 MaxClients and ThreadsPerChild.

+ +

With the perchild MPM, use this directive only + if you need to set NumServers higher than 8 (default).

+ +

Note

+

There is a hard limit of ServerLimit 20000 compiled + into the server. This is intended to avoid nasty effects caused by + typos.

+
+ +

See also

+ +
+
top
+

StartServers Directive

+ + + + + + + +
Description:Number of child server processes created at startup
Syntax:StartServers number
Default:See usage for details
Context:server config
Status:MPM
Module:leader, mpmt_os2, prefork, threadpool, worker
+

The StartServers 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.

+ +

The default value differs from MPM to MPM. For + leader, threadpool and + worker the default is StartServers 3. + For prefork defaults to 5 and for + mpmt_os2 to 2.

+ +
+
top
+

StartThreads Directive

+ + + + + + + +
Description:Number of threads created on startup
Syntax:StartThreads number
Default:See usage for details
Context:server config
Status:MPM
Module:beos, mpm_netware, perchild
+

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.

+ +

For perchild the default is StartThreads + 5 and this directive tracks the number of threads per + process at startup.

+ +

For mpm_netware the default is + StartThreads 50 and, since there is only a single + process, this is the total number of threads created at startup to + serve requests.

+ +

For beos the default is StartThreads + 10. It also reflects the total number of threads created + at startup to serve requests.

+ +
+
top
+

ThreadLimit Directive

+ + + + + + + + +
Description:Sets the upper limit on the configurable number of threads +per child process
Syntax:ThreadLimit number
Default:See usage for details
Context:server config
Status:MPM
Module:leader, mpm_winnt, perchild, threadpool, worker
Compatibility:Available for mpm_winnt in Apache 2.0.41 +and later
+

This directive sets the maximum configured value for ThreadsPerChild for the lifetime + of the Apache process. Any attempts to change this directive + during a restart will be ignored, but ThreadsPerChild can be modified + during a restart up to the value of this directive.

+ +

Special care must be taken when using this directive. If + ThreadLimit is set to a value much higher + than ThreadsPerChild, + extra unused shared memory will be allocated. If both + ThreadLimit and ThreadsPerChild 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 ThreadsPerChild for the + current run of Apache.

+ +

The default value for ThreadLimit is + 1920 when used with mpm_winnt and + 64 when used with the others.

+ +

Note

+

There is a hard limit of ThreadLimit 20000 (or + ThreadLimit 15000 with mpm_winnt) + compiled into the server. This is intended to avoid nasty effects + caused by typos.

+
+ +
+
top
+

ThreadsPerChild Directive

+ + + + + + + +
Description:Number of threads created by each child process
Syntax:ThreadsPerChild number
Default:See usage for details
Context:server config
Status:MPM
Module:leader, mpm_winnt, threadpool, worker
+

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 mpm_winnt, + 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 worker, where there are multiple child processes, + the total number of threads should be high enough to handle + the common load on the server.

+ +

The default value for ThreadsPerChild is + 64 when used with mpm_winnt and + 25 when used with the others.

+ +
+
top
+

User Directive

+ + + + + + + + +
Description:The userid under which the server will answer +requests
Syntax:User unix-userid
Default:User #-1
Context:server config
Status:MPM
Module:leader, perchild, prefork, threadpool, worker
Compatibility:Only valid in global server config since Apache +2.0
+

The User 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 root. + 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 root, + then it is normal for the parent process to remain running as root. + Unix-userid is one of:

+ +
+
A username
+
Refers to the given user by name.
+ +
# followed by a user number.
+
Refers to a user by its number.
+
+ +

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 nobody, but + this is not always desirable, since the nobody user + can have other uses on the system.

+ +

Security

+

Don't set User (or Group) to root unless + you know exactly what you are doing, and what the dangers are.

+
+ +

With the perchild MPM, which is intended to + server virtual hosts run under different user IDs, the + User directive defines the user ID for the + main server and the fallback for <VirtualHost> sections without an + AssignUserID directive.

+ +

Special note: Use of this directive in <VirtualHost> is no longer supported. To + configure your server for suexec use + SuexecUserGroup.

+ +

Note

+

Although the User directive is present + in the beos and mpmt_os2 MPMs, + it is actually a no-op there and only exists for compatibility + reasons.

+
+ +
+
+
+

Available Languages:  de  | + en  | + es  | + ja  | + tr 

+
+ \ No newline at end of file -- cgit 1.2.3-korg