[users@httpd] More usage of network bandwidth with Apache Proxy Server

[Saleem <sa...@cordys.com>]

Hi,

We have been using Apache Proxy Server and we have noticed some strange 
behavior w.r.t network usage.

The network usage of Apache Proxy server and the client machine which is

connected to it are being monitored. A download 
(http://ftp.surfnet.nl/ftp/pub/os/Linux/distr/fedora/1/i386/iso/) have
been 
initiated from the client machine. Before the download gets completed,
it is 
cancelled from the client.

It is noticed that the network usage of Apache Proxy Server is still
high, 
even if the download gets cancelled and it remains high for considerable
time( 
the time equivalent for the entire download to complete). 

What are the reasons for this behavior?

To ascertain the fact that Proxy server still process the download, when
it is 
cancelled from client, we did few more tests with only one client
connected to 
Apache Proxy. 

1. Download initiated from client, cancelled it after 20 minutes. The
after 20 
minutes, the Apache Proxy Server is stopped.

It is noticed that as soon as download is initiated, the network
bandwidth 
usage (transmit bps ) by Apache Proxy Server goes high ( almost 0.8 Mbps
). 
When the download is cancelled from client, the transmit bps of Apache
proxy 
serve remains same. 

Only when Apache is stopped, the transmit bps comes down (obvious). In
one of 
the tests, Apache was not stopped, and monitored the transmit bps, which
has 
remained high for the time equivalent to complete download time.

2. Two proxy servers were used in the second test, where the client is 
connected to first Apache Proxy Server, which is connected to Second
Proxy 
Server.

The download is initiated from client, cancelled it from client, then
First 
Apache Proxy Server is stopped and Finally Second Apache Proxy Server is

stopped.

When the download is cancelled, the transmit bps of both the First
Apache 
Proxy and Second Apache Proxy remains high. Even if the First Proxy
Server is 
stopped, the transmit bps of Second Proxy Server remains high.

3. Different versions of Apache have been tried.

The same behavior is exhibited with httpd 2.0.48, 2.0.50 and 2.2.0. 


We would like to know why is such behavior being exhibited by Apache
Proxy. 

In case, more information is required, I can send more details.



Regards,
Saleem





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