Apache HTTP Сервер Версия 2.0
Apache MPM Common Directives
Описание: | A collection of directives that are implemented by more than one multi-processing module (MPM) |
---|---|
Статус: | MPM |
Директивы
- AcceptMutex
- BS2000Account
- CoreDumpDirectory
- EnableExceptionHook
- Group
- Listen
- ListenBackLog
- LockFile
- MaxClients
- MaxMemFree
- MaxRequestsPerChild
- MaxSpareThreads
- MinSpareThreads
- PidFile
- ReceiveBufferSize
- ScoreBoardFile
- SendBufferSize
- ServerLimit
- StartServers
- StartThreads
- ThreadLimit
- ThreadsPerChild
- User
AcceptMutex Директива
Описание: | Method that Apache uses to serialize multiple children accepting requests on network sockets |
---|---|
Синтаксис: | AcceptMutex Default|method |
По умолчанию: | AcceptMutex Default |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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 theLockFile
directive. fcntl
- uses the
fcntl(2)
system call to lock the file defined by theLockFile
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
.
BS2000Account Директива
Описание: | Define the non-privileged account on BS2000 machines |
---|---|
Синтаксис: | BS2000Account account |
Контекст: | server config |
Статус: | MPM |
Модуль: | perchild , prefork |
Совместимость: | 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
.
Примечание
Only one BS2000Account
directive can be used.
См также
CoreDumpDirectory Директива
Описание: | Directory where Apache attempts to switch before dumping core |
---|---|
Синтаксис: | CoreDumpDirectory directory |
По умолчанию: | See usage for the default setting |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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
.
EnableExceptionHook Директива
Описание: | Enables a hook that runs exception handlers after a crash |
---|---|
Синтаксис: | EnableExceptionHook On|Off |
По умолчанию: | EnableExceptionHook Off |
Контекст: | server config |
Статус: | MPM |
Модуль: | leader , perchild , prefork , threadpool , worker |
Совместимость: | 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
Group Директива
Описание: | Group under which the server will answer requests |
---|---|
Синтаксис: | Group unix-group |
По умолчанию: | Group #-1 |
Контекст: | server config |
Статус: | MPM |
Модуль: | beos , leader , mpmt_os2 , perchild , prefork , threadpool , worker |
Совместимость: | 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.
Пример
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.
Безопасность
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
.
Listen Директива
Описание: | IP addresses and ports that the server listens to |
---|---|
Синтаксис: | Listen [IP-address:]portnumber |
Контекст: | server config |
Статус: | MPM |
Модуль: | beos , leader , mpm_netware , mpm_winnt , mpmt_os2 , perchild , prefork , threadpool , worker |
Совместимость: | 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
MultipleListen
directives for the same ip
address and port will result in an Address already in use
error message.
См также
ListenBackLog Директива
Описание: | Maximum length of the queue of pending connections |
---|---|
Синтаксис: | ListenBacklog backlog |
По умолчанию: | ListenBacklog 511 |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
LockFile Директива
Описание: | Location of the accept serialization lock file |
---|---|
Синтаксис: | LockFile filename |
По умолчанию: | LockFile logs/accept.lock |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
Безопасность
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.
См также
MaxClients Директива
Описание: | Maximum number of child processes that will be created to serve requests |
---|---|
Синтаксис: | MaxClients number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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
.
MaxMemFree Директива
Описание: | Maximum amount of memory that the main allocator is allowed
to hold without calling free() |
---|---|
Синтаксис: | MaxMemFree KBytes |
По умолчанию: | MaxMemFree 0 |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
MaxRequestsPerChild Директива
Описание: | Limit on the number of requests that an individual child server will handle during its life |
---|---|
Синтаксис: | MaxRequestsPerChild number |
По умолчанию: | MaxRequestsPerChild 10000 |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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 limit has two beneficial effects:
- it limits the amount of memory that process can consume by (accidental) memory leakage;
- by giving processes a finite lifetime, it helps reduce the number of processes when the server load reduces.
Примечание
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.
MaxSpareThreads Директива
Описание: | Maximum number of idle threads |
---|---|
Синтаксис: | MaxSpareThreads number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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:
perchild
requiresMaxSpareThreads
to be less or equal thanThreadLimit
.mpm_netware
wants the value to be greater thanMinSpareThreads
.- For
leader
,threadpool
andworker
the value must be greater or equal than the sum ofMinSpareThreads
andThreadsPerChild
.
См также
MinSpareThreads Директива
Описание: | Minimum number of idle threads available to handle request spikes |
---|---|
Синтаксис: | MinSpareThreads number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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
.
См также
PidFile Директива
Описание: | File where the server records the process ID of the daemon |
---|---|
Синтаксис: | PidFile filename |
По умолчанию: | PidFile logs/httpd.pid |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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
.
Пример
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 Безопасность.
Примечание
As of Apache 2 it is recommended to use only the apachectl
script for (re-)starting or stopping the server.
ReceiveBufferSize Директива
Описание: | TCP receive buffer size |
---|---|
Синтаксис: | ReceiveBufferSize bytes |
По умолчанию: | ReceiveBufferSize 0 |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
ScoreBoardFile Директива
Описание: | Location of the file used to store coordination data for the child processes |
---|---|
Синтаксис: | ScoreBoardFile file-path |
По умолчанию: | ScoreBoardFile logs/apache_status |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
Пример
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 Безопасность.
См также
SendBufferSize Директива
Описание: | TCP buffer size |
---|---|
Синтаксис: | SendBufferSize bytes |
По умолчанию: | SendBufferSize 0 |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
ServerLimit Директива
Описание: | Upper limit on configurable number of processes |
---|---|
Синтаксис: | ServerLimit number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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).
Примечание
There is a hard limit of ServerLimit 20000
compiled
into the server. This is intended to avoid nasty effects caused by
typos.
См также
StartServers Директива
Описание: | Number of child server processes created at startup |
---|---|
Синтаксис: | StartServers number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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
.
StartThreads Директива
Описание: | Number of threads created on startup |
---|---|
Синтаксис: | StartThreads number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
ThreadLimit Директива
Описание: | Sets the upper limit on the configurable number of threads per child process |
---|---|
Синтаксис: | ThreadLimit number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | leader , mpm_winnt , perchild , threadpool , worker |
Совместимость: | 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.
Примечание
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.
ThreadsPerChild Директива
Описание: | Number of threads created by each child process |
---|---|
Синтаксис: | ThreadsPerChild number |
По умолчанию: | See usage for details |
Контекст: | server config |
Статус: | MPM |
Модуль: | 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.
User Директива
Описание: | The userid under which the server will answer requests |
---|---|
Синтаксис: | User unix-userid |
По умолчанию: | User #-1 |
Контекст: | server config |
Статус: | MPM |
Модуль: | leader , perchild , prefork , threadpool , worker |
Совместимость: | 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.
Безопасность
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
.