Apache Web Server Tunings For High Performance
1.3.2x 2.x
1.3.2x
Apache version 1.3.2x has more tunable parameters on UNIX than on Windows.
Windows requires a different programming model. The following parameters
are tuned for large SMP systems with 4GB+ RAM and multiple CPUs, and they are
meant for running enterprise applications such as those designed for hundreds of
thousands of users, with multiple Apache servers in a topology. Update the
parameters in the httpd.conf file.
|
Tuning Parameter |
Unix value |
Windows value |
Description |
|
MaxClients (UNIX)
ThreadsPerChild (Windows) |
1000 |
800 |
Set this value to the number of
concurrent users expected. Monitor your system during normal
workload to see if this value needs to be changed. Use lower for
simple but CPU intensive applications, and higher for more complex,
database-intensive applications with more wait time. |
|
KeepAlive |
NA |
on |
Enables HTTP persistent connections.
Used with MaxKeepAliveRequests. |
|
KeepAliveTimeout
(seconds) |
10 |
15 |
Set this parameter similar to the
average think time for your workload. Higher Keep-Alive Timeout may
increase contention for HTTP server processes. If you see “running
out of HTTP processes” in the http error log, you may want to
decrease this value. |
|
MaxKeepAliveRequests |
0 |
0 |
This allows
an unlimited number of
requests on a single TCP connection. |
|
MaxRequestsPerChild |
0 |
0 |
Do not force a server to exit after
it has served certain number of requests. If your version of Apache
and Apache library has no known memory leaks, set this to 0. But if
you wish to force the server to exit and be re-created, set this to
a relatively high number, e.g., 25000. |
|
StartServers |
10 |
NA |
This makes a pool of servers ready on
startup. Specify this number to match the MaxSpareServers
parameter. |
|
MaxSpareServers |
10 |
NA |
This sets the desired maximum number
of idle child server processes that are ready to take of if the
request-taking child dies. The parent process will kill off the
excess processes if the number is more than MaxSpareServers. |
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Additionally, from the Apache Project web site,
http://httpd.apache.org/docs/1.3/misc/perf-tuning.html#runtime, there are
other httpd.conf setting worth noting, for example, do not allow hostname
lookups:
Note that it's possible to scope the directives, such as within a <Location
/server-status> section. In this case the DNS lookups are only performed on
requests matching the criteria. Here's an example which disables lookups except
for .html and .cgi files:
HostnameLookups off
<Files ~ "\.(html|cgi)$">
HostnameLookups on
</Files> |
2.xCompared to Apache
1.3, release 2.0 contains many additional optimizations to increase
throughput and scalability (e.g., MaxRequestsPerChild by default is already
set to 0 as above for v1.3). Most of these improvements are enabled by
default. However, there are
compile-time and run-time
configuration choices that can significantly affect performance.
This
document describes the options that a server administrator can configure
to tune the performance of an Apache 2.0 installation. Some excerpt:
FollowSymLinks and SymLinksIfOwnerMatch
Wherever in your URL-space you do not have an Options FollowSymLinks, or
you do have an Options SymLinksIfOwnerMatch Apache will have to issue extra
system calls to check up on symlinks. One extra call per filename component.
For example, if you had:
DocumentRoot /www/htdocs
<Directory />
Options SymLinksIfOwnerMatch
</Directory> |
and a request is made for the URI /index.html. Then
Apache will perform lstat(2) on
/www, /www/htdocs, and /www/htdocs/index.html. The results of these lstats
are never cached, so they will occur on every single request. If you
really desire the symlinks security checking you can do something like this:
DocumentRoot /www/htdocs
<Directory />
Options FollowSymLinks
</Directory>
<Directory /www/htdocs>
Options -FollowSymLinks +SymLinksIfOwnerMatch
</Directory> |
This at least avoids the extra
checks for the DocumentRoot path. Note that you'll need to add
similar sections if you have any Alias or RewriteRule paths outside of your
document root. For highest performance, and no symlink protection, set
FollowSymLinks everywhere, and never set SymLinksIfOwnerMatch.
So much more at:
http://httpd.apache.org/docs/2.0/misc/perf-tuning.html.
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