190

Chapter 14. Apache HTTP Server

14.5.3.

PidFile

PidFile

names the file where the server records its process ID (pid). Your Web server is set to record

its pid in

/var/run/httpd.pid

.

14.5.4.

ScoreBoardFile

The

ScoreBoardFile

stores internal server process information, which is used for communication

between the parent server process and its child processes. Red Hat Linux uses shared memory to store

the

ScoreBoardFile

, the default of

/etc/httpd/logs/apache_runtime_status

is only used

as a fallback.

14.5.5.

Timeout

Timeout

defines, in seconds, the amount of time that your server will wait for receipts and trans 

missions during communications. Specifically,

Timeout

defines how long your server will wait to

receive a GET request, how long it will wait to receive TCP packets on a POST or PUT request and

how long it will wait between ACKs responding to TCP packets.

Timeout

is set to 300 seconds,

which is appropriate for most situations.

14.5.6.

KeepAlive

KeepAlive

sets whether your server will allow more than one request per connection (in other words,

it will allow persistent connections).

KeepAlive

can be used to prevent any one client from consum 

ing too much of the server's resources.

By default Keepalive is set to off. If Keepalive is set to on and the server becomes very busy, the

server can quickly spawn the maximum number of child processes. In this situation, the server will

slow down significantly. If Keepalive is enabled, it is a good idea to set the the KeepAliveTimeout low

(see Section 14.5.8) and monitor the servers

/var/log/httpd/error_log

. This log will report

when the server is running out of child processes.

14.5.7.

MaxKeepAliveRequests

This directive sets the maximum number of requests allowed per persistent connection. The Apache

Group recommends a high setting, which will improve your server's performance.

MaxKeepAliv 

eRequests

is set to

100

by default, which should be appropriate for most situations.

14.5.8.

KeepAliveTimeout

KeepAliveTimeout

sets the number of seconds your server will wait after a request has been served

before it closes the connection. Once the server receives a request, the

Timeout

directive applies

instead.

14.5.9.

MinSpareServers

and

MaxSpareServers

The Apache HTTP Server dynamically adapts to the perceived load by maintaining an appropriate

number of spare server processes based on the traffic. The server checks the number of servers waiting

for a request and kills some if there are more than

MaxSpareServers

or creates some if the number

of servers is less than

MinSpareServers

.