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From "Terence M. Bandoian" <tere...@tmbsw.com>
Subject Re: Slow downloads through mod_jk on Windows XP
Date Thu, 10 May 2012 20:07:24 GMT
  On 1:59 PM, Christopher Schultz wrote:
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> Andy,
>
> On 5/8/12 6:41 PM, Andy Wang wrote:
>> Initial benchmarks seem to show that the behavior between tomcats
>> is not an issue.
> Do you mean that Tomcat performance appears to be the same regardless
> of version? That's both good and bad... I thought there were some
> performance improvements to the connectors from 5.5->  6.0. Maybe that
> was 4.x->5.5.
>
>> Tomcat7 is using JDK 1.7 and this is interesting.  The benchmarks
>> with tomcat7+jdk1.7 vary widely across the board (both through ajp
>> and direct http to tomcat) from 30s-40sMB/s. Java 1.6 seems alot
>> more consistent.  Not sure why yet.
> That is interesting. On the other hand, the server /is/ on a virtual
> machine, and you never know what other processes are stealing focus.
> Many VMs are notorious for bad IO throughput (I'm looking at you, OpenVZ).
>
>> I've also moved off the crappy Windows XP VM I was provided to a
>> more recent Windows 2008 VM as well as a fresh Windows XP SP3 VM.
>> In past experience it seems windows XP and windows 2003 were the
>> worst of the bunch with the ajp downloads dropping as low as
>> 4-5MB/s over time.
> Have you tried bare hardware?


How much control do you have over the VM server?  Seems to me that 
resources/performance could be not only affected by other VMs but also 
intentionally throttled.

-Terence Bandoian


>> I'm going to run a barrage of tests and provide the numbers.  Do
>> you think ab -n 5 and allowing ab to average the values of 5 hits
>> for the ~440MB iso is a sound average?
> Some tips for this kind of testing:
>
> 1. Don't run ab on localhost: all the numbers will be worthless
> 2. Run ab with a range of concurrencies, including c=1
> 3. Make /lots/ of requests. IMO, 5 requests is really a pinhole
> analysis. I would make as many requests as you can over 10 minutes and
> see what the throughput ends up being.
>
>> I'll compare Windows XP performance and Windows 2008 performance
>> and after that I'll do the same on a Linux VM to get a better
>> comparison.
> It will be good to see.
>
> If you want some really crappy scripts to get you going, feel free to
> start with mine from a while back (look in the "scripts" subdir):
> http://people.apache.org/~schultz/ApacheCon%20NA%202010/
>
> Those scripts can run a ... lot of ab tests with lots of different
> concurrencies against a series of URLs -- that allows you to set up
> everything with, say, a different path or port number to get the
> various setups (bare httpd, httpd+mod_jk, httpd+mod_proxy, etc.) and
> then let it run all night. It will also produce some tables for you
> that can then easily be graphed.
>
>> I also did bump up the ajpPacket size to 64K with no noticeable
>> change to the benchmark numbers.  So while 8k seems crappy it
>> doesn't seem to be an issue.  Given that apache and tomcat are both
>> local I wouldn't expect that to be a big problem with 8k chunks
>> given the near non-existent latency of local connections.
> It's good to know that the packet size didn't affect performance, but
> I agree that localhost communication is always magically-fast no mater
> what.
>
>> I plan on doing both local ab requests as well as remote.  The
>> problem with remote is that our network is busy, so it may account
>> for some variations but I don't think I can get our IT to segment
>> me anything for this purpose :(.
> Just get a crossover cable and use static IP addresses.
>
>> I'm not so concerned about a 25% hit.  I'm really more concerned
>> with the drop to 4-5MB/s over time that seems to happen.
> Does this happen locally or only remotely? I wonder if you're hitting
> some kind of traffic-shaping or QOS rules on your own internal network.
>
> - -chris

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