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From Andy Wang <>
Subject Re: Slow downloads through mod_jk on Windows XP
Date Tue, 08 May 2012 21:04:37 GMT
After playing with this a bit more (testing this time against tomcat 7.0.27)
the ajpPacketSize has zero effect on the speed.

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 

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 

the numbers are pretty consistent. So apache still beats tomcat by a 
good chunk but it's much much better than with tomcat 5.0 where the 
through tomcat numbers were about half that.

I'm still wondering if there's something that can be tweaked in the MS 
TCP/IP stack to bring the two together closer.


On 05/08/2012 02:06 PM, Andy Wang wrote:
> On 05/07/2012 06:50 PM, Andy Wang wrote:
>> On 05/07/2012 06:06 PM, André Warnier wrote:
>>> Considering your setup, it should not be too hard to set up a 
>>> download of the same file file directly from Tomcat (through its 
>>> HTTP Connector), to compare that with your two previous ways. This 
>>> way, you could make sure if it is Tomcat, or the mod_jk/AJP link 
>>> which is the issue.
>>> Also, still considering your setup, it should be possible to 
>>> configure things so that these file downloads are handled directly 
>>> by Apache httpd, since that seems to satisfy your expectations. 
>>> mod_jk "JkMount/JkUnMount" rules (*) should make that possible, no ?
>>> Have to be a bit careful not to introduce security holes, and I am 
>>> assuming that the files are static (which may be wrong here).
>>> (*) or the <Location ..> + "setHandler jakarta-servlet" 
>>> configuration variation
>> Thanks for the http connector idea. I forgot about that. The primary 
>> reason why i'm using tomcat to download a static file is really for 
>> testing purposes to confirm performance between mod_jk and direct 
>> apache. we have servlets that stream content files that see the same 
>> massive performance hit so in our actual use case it's not static 
>> files :(. I'm thinking this would be a valid test to help at least 
>> tweak mod_jk to it's potential.
>> We've checked and double checked the buffering code of the servlets 
>> and it all looks fine AND the performance is fine on Linux and the 
>> speed characteristics are identical to serving static files through 
>> tomcat + mod_jk so I'm hoping that it's an apples to apples comparison.
>> Andy
> Through the HTTP connector the performance is similar to apache 
> direct. 30mb/s
> So there's something interesting going on specifically ajp.
> Andy
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