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From pc3 <peter.r.cl...@gmail.com>
Subject large-scale app.. random spiking on even static files!
Date Sat, 09 Aug 2008 03:55:36 GMT

hey all -

so i've spent the past two weeks trying to figure out why my large scale
application (200m page views per month) is having some serious, yet random,
spikes in response times.  

we've got an app running under gero 1.1.1, using hibernate, mysql, etc.  
i've got the response times down in general by adding memcaching and other
optimizations but we still see the spikes.. e.g. most of our actions return
in 0.1 sec, but occasionally (and often enough!) .. we'll see a random spike
up to 30s from different machines in our cluster. 

so for kicks tonight i tried running a test against all of our app servers
not for an action but for a plain .txt file ... and guess what... spiky
responses just from the txt file!  a 4.9kb text file!  look:

$profileUrl /blah/Languages.txt
Host 192.168.1.100
Time taken for tests:   8.555825 seconds <<<<<<<<<<<<
Host 192.168.1.101
Time taken for tests:   0.2064 seconds
Host 192.168.1.108
Time taken for tests:   0.1436 seconds
Host 192.168.1.104
Time taken for tests:   0.1667 seconds
Host 192.168.1.112
Time taken for tests:   0.1444 seconds
Host 192.168.1.117
Time taken for tests:   0.4575 seconds
Host 192.168.1.118
Time taken for tests:   0.2015 seconds
Host 192.168.1.119
Time taken for tests:   0.2003 seconds
Host 192.168.1.120
Time taken for tests:   0.1713 seconds
Host 192.168.1.121
Time taken for tests:   7.22861 seconds <<<<<<<<<<<<
Host 192.168.1.122
Time taken for tests:   0.1615 seconds

Here are some things to go on:
1) we still host a few swfs from these servers that are hit frequently. 
could these be causing some kind of blocking?
2) we have a method in our application that acts as a proxy, taking a url as
a parameter, fetching the url then dumping it to the response 

I'm open to any ideas or suggestions as to what could be causing the
spikiness of response times here for a txt file.. one that never even hits
our java code.   

Thanks very much all...

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View this message in context: http://www.nabble.com/large-scale-app..-random-spiking-on-even-static-files%21-tp18902003s134p18902003.html
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