Understanding Process-Based MPMs


In a process-based server, the server forks several children. Forking means that a parent process makes identical copies of itself, called children. Each one of the children can serve a request independently of the others. This approach has the advantage of improved stability; if one of the children misbehaves, for example, by leaking memory, it can be killed without affecting the rest of the server.

The increased stability comes with a performance penalty: Each one of the children occupies additional memory, and the operating system spends a certain amount of time in context switching. In addition, this approach makes inter-process communication and data sharing difficult.

Apache 1.3 is a process-based server and Apache 2 provides a prefork MPM that allows it to perform as a process-based server. Prefork means that children can be forked at startup, instead of when a request comes. Apache allows you to configure the number of children to fork at startup and the maximum number of possible children, as described in the next section.




Apache(c) Phrase Book(c) Essential Code and Commands
Apache Phrasebook
ISBN: 0672328364
EAN: 2147483647
Year: 2006
Pages: 254

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net