Httpd.exe using lot of Memory on Windows

We are running an application which uses Apache 2.2.22 as a WebServer on Windows Server 2008 R2 Enterprise.

Looking at the httpd.exe child process in Process Explorer, we see the Private Bytes increasing by 60 MB every day.

This makes it mandatory to restart Apache every 9 working days when Apache hits at it’s peak of around 1.2 GB.

Server-status shows:

Total accesses: 1042790 - Total Traffic: 552.1 GB
3.2 requests/sec - 1.7 MB/second - 0.5 MB/request
90 requests currently being processed, 510 idle workers

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Hardware:

Intel(R) Xeon(R) CPU E5-2609 @2.40 GHz (2 processors)
RAM: 128 GB

httpd.conf:

KeepAliveTimeout 60
SendBufferSize 16384
Timeout 900
ThreadsPerChild 600

We did ran Apache Benchmark tool on some urls (urls from application and also Apache index.html). However we dint observed any memory increase.

We thought of using MaxRequestsPerChild, but since it’s a Windows machine, with one child process, it will cause Apache to restart.

The server is a Production server and used 24 x 7. I would like to understand how can I reproduce the memory increase on exactly similar cloned TEST

environment. What are the factors which can impact the memory?

I already have a TEST environment, with the only difference of load and usage.

I will also appreciate if I can get any pointer to identify what is taking this memory on windows and where to look at?

Thanks,
Nitin