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From Sindhi Sindhi <>
Subject Re: Apache pool management
Date Sat, 25 May 2013 12:57:04 GMT
Thankyou very much!

On Sat, May 25, 2013 at 2:21 PM, Sorin Manolache <> wrote:

> On 2013-05-25 10:05, Sindhi Sindhi wrote:
>> You have answered all my questions and thanks a lot. Had two questions
>> more, appreciate your response.
>> 1.
>> As of now, my httpd.conf file has the below lines-
>> # Server-pool management (MPM specific)
>> #Include conf/extra/httpd-mpm.conf
>> This means Apache does not read the httpd-mpm.conf file during startup.
>> And
>> so it uses the default settings for "Max number of requests it can
>> support"
>> and "Max number of threads it creates per child process"
>> Where can I find what default values Apache uses for the following -
>> - Upto how many concurrent requests will Apache support by default
>> - Max number of threads that one child process creates
>> For ex. if I want Apache to handle upto 400 concurrent requests at a time,
>> how will I know that this 400 is within the default settings that Apache
>> uses.
> Have a look here, depending on your version of apache.
> The number of threads per process is given in ThreadsPerChild.
> You typically tweak
> ServerLimit (the maximum number of children that are simultaneously alive)
> ThreadLimit (the maximum sum of alive threads in all children)
> StartServers (how many children are created upon startup)
> ThreadsPerChild
> MaxRequestWorkers (or MaxClients in 2.2) (the maximum number of requests
> that are served simultaneously)
> MaxConnectionsPerChild (or MaxRequestsPerChild in 2.2) (after a child has
> served that many requests, it exits and is potentially replaced with a new
> child; avoids memleaks)
> MinSpareThreads and MaxSpareThreads, the minimum and maximum number of
> spare threads.
> There are some constraints on the arguments of these directives, which I
> do not master. I think that MaxRequestWorkers <= ThreadsPerChild *
> ServerLimit and that MaxRequestWorkers and ThreadLimit should be divisible
> by ThreadsPerChild, but as I said, I do not master. If you get them wrong,
> apache adjusts the values automatically and informs you about it upon
> startup.
> I am not sure, maybe others on the list can confirm or deny, but I think
> that apache does not distinguish between threads and processes in windows:
> So I think that ServerLimit = 1 in Windows and probably
> MaxConnectionsPerChild is not used or does not exist.
> You may also have a look at KeepAlive On|Off, MaxKeepAliveRequests and
> KeepAliveTimeout (**2.4/mod/core.html<>
> )
> If my module is on the internet with hundreds of thousands of possible
> client IPs that issue one request and then leave, I set KeepAlive Off. If
> my module is on the intranet and is accessed by a couple of webservices
> that continuously issue requests, I set it On with a short timeout.
> Performance-wise the KeepAlive directive makes a huge difference.
>  2.
>> My understanding is, once a request is completely processed, Apache frees
>> the pool of only this request and does not free any other request's pool.
>> And other request pools will be freed only when those requests are
>> completely processed. Kindly confirm my understanding to be correct.
> Yes, it is correct.
> Sorin

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