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From André Warnier ...@ice-sa.com>
Subject Re: Slow downloads through mod_jk on Windows XP
Date Tue, 08 May 2012 22:09:54 GMT
Caldarale, Charles R wrote:
>> From: Andy Wang [mailto:awang@ptc.com] 
>> Subject: Re: Slow downloads through mod_jk on Windows XP
> 
>> Downloading a large file through mod_jk to tomcat looks like this:
>> 2012-05-08 16:01:22 (15.0 MB/s) - "sol-11-1111-text-x86.iso.8" saved 
>> [450799616/450799616]
> 
>> Downloading the same large file directly through apache looks like:
>> 2012-05-08 16:01:58 (19.3 MB/s) - "sol-11-1111-text-x86.iso.11" saved 
>> [450799616/450799616]
> 
>> So apache still beats tomcat by a good chunk
> 
> No, httpd (not Apache, which is an open source software organization) beats httpd+Tomcat
- any other result would be violating several laws of physics.  Might be interesting to measure
just Tomcat in your environment.
> 

He did that previously, and the result seemed to be that Tomcat alone was comparable to 
httpd alone, and both were better than httpd/mod_jk + Tomcat; which is indeed physically 
to be expected : more tubing, less throughput (excepting quantum tunelling effects of 
course).
The question is more : how much of a degradation ?
15.0/19.3 = 0.77 = 23% less throughput.  I don't know if this is "a good chunk" or the "to

be expected" kind of degradation.

According to the (looking seriously outdated) AJP protocol documentation at 
http://tomcat.apache.org/connectors-doc/ajp/ajpv13a.html, it would seem that the maximum 
data size "chunk" which AJP can send back from Tomcat to the front-end httpd is 8K at a 
time.  So AJP might not be very well suited, when it comes to send back big blobs of data.

Rainer would need to confirm if that is still the case now.

One earlier message seemed to indicate that this "httpd/mod_jk+tomcat deficit" only 
happened under Windows though, and not under Linux.  If that is confirmed, maybe there is

some subtle difference in how the TCP/IP stack is being used under the one vs the other ?


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