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I am facing a problem in Apache server when the number of users reaches around 250 concurrent. The problem occurred only when the idle worker number was set to 0.

So my question is, does a single Apache worker serves only 1 request or more than that? How can I increase worker or max user to be at least 700 concurrent?

i am using Apache 2.2 on Windows 2008 R2 and MPM type is : mpm_winnt.

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Are you actually using the worker mpm or maybe the more common prefork? Use httpd -l to learn which is in use. – Sven Apr 21 '13 at 14:59
in windows how i can know ? – Koptan Apr 21 '13 at 15:10
Same command in Windows.... – Chris S Apr 21 '13 at 16:21

mpm_winnt seems to be pretty close in design to mpm_worker. mpm_worker uses several processes (servers) with multiple threads per process to serve connections. mpm_winnt uses just one process.

So, you can tune the number of concurrent connections using ThreadLimit and ThreadsPerChild directives.

Please read the docs before blindly changing those two.

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Look at MaxClients - this is a common setting for prefork and worker.

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i am using mpm_winnt is MaxClients work also work in Winnt MPM ? – Koptan Apr 21 '13 at 19:59

For a typical smaller server configuration, with Prefork MPM, you probably want something like:

StartServers 5
MinSpareServers 1
MaxSpareServers 10
ServerLimit 500
MaxClients 500
MaxRequestsPerChild 5000

Note, this puts the limit at 500. If you want more than that just increase the value. The values are sensible for generic small websites, but if you're site isn't "generic" you really need to take some time and tailor these values to your site.

If you're getting much larger than this, it's time to switch to a different MPM, like worker or event. This may require changing various aspects of the site however, depending on what technologies you're using.

For a Threaded MPM (Event, Worker) and a generic smaller website:

StartServers 5
MinSpareThreads 1
MaxSpareThreads 10
MaxClients 1024
ThreadsPerChild 64
MaxRequestsPerChild 50000

MPM WinNT only has a single process (child), so you'd want to bump the ThreadsPerChild to something sensible. Another answer has links to the relevant Apache man pages.

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i am using Winnt MPM,dose the above configurations work also in Winnt MPM? – Koptan Apr 21 '13 at 20:01
Nope, ignore that, see edit. – Chris S Apr 22 '13 at 0:05

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