Apache Reference Manual (8)

Maxrequestsperchild directive
Syntax:maxrequestsperchild number
Default:maxrequestsperchild 0
Context:server Config
Status:core
The maxrequestsperchild directive sets the limit on the number of requests of this a individual child server process would ha Ndle. After Maxrequestsperchild requests, the child process would die. If maxrequestsperchild is 0, then the process would never expire.
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 to reduce the number of processes when the server load reduces.
This is directive has no effect on Win32.
Note:for KeepAlive requests, only the ' the ' is counted towards this limit. In effect, it changes the "behavior to limit" number of connections per child.
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maxspareservers directive
Syntax:maxspareservers number
Default:maxspareservers 10
Context:server Config
Status:core
The maxspareservers directive sets the desired maximum number of idle child server processes. An idle process is one which isn't handling a request. If There are more than maxspareservers idle, then the parent process would kill off the excess processes.
Tuning of this parameter should is necessary on very busy. Setting This parameter to a large number are almost always a bad idea.
This directive has no effect when used with the Apache Web server on a Microsoft Windows platform.
Also Minspareservers and startservers.
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minspareservers directive
Syntax:minspareservers number
Default:minspareservers 5
Context:server Config
Status:core
The minspareservers directive sets the desired minimum number of idle child server processes. An idle process is one which isn't handling a request. If there are fewer than minspareservers idle, then the parent process creates new children at a maximum rate of 1 per Seco nd.