Hi Arnab, On Apr 1, 2007, at 9:53 PM, Arnab Ganguly wrote:
Want some info when the MaxClient value is reached, what would happen to Apache webserver?Is that particular of time if we ping apache it will time out.How long will it take to recover or the requests will be queued? Can you tell me is there any configurable parameter in NES similar to MaxClient settings in Apache.ie the max simulatenous request it can handle?
The MaxClients directive dictates the maximum number of child processes (prefork) or worker threads (other MPMs) Apache can spawn. Its name is slightly misleading: MaxClients does not actually dictate the maximum number of clients that can connect to the web server. It does, however, dictate the maximum number of requests Apache can handle concurrently.
As TCP connections arrive on Apache's listening socket, they are queued by the kernel. All the Apache workers receive these TCP connections in the order in which they arrived. If Apache handles the requests fast enough, the queue will be mostly empty and any new connection will be received by an Apache worker immediately. If the server is busy, requests may queue up and the client's browser will say 'Connecting to... ' in the status bar. The number of connections that can queue up is platform-specific, but you can manipulate it using the ListenBacklog directive:
http://httpd.apache.org/docs/2.2/mod/mpm_common.html#listenbacklogOnly when the kernel's queue is full, and all Apache children are busy will the server refuse new incoming connections, and the way in which this happens also depends on the server platform.
Of course all of this happens on the Apache listening socket, and has nothing to do with ping (ICMP) which is handled completely inside the kernel.
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