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From Deepak Shetty <shet...@gmail.com>
Subject Re: a good script to start several jmeter instances, and how to kill my web server to find its threshold?
Date Wed, 10 Mar 2010 21:09:50 GMT
#1 http://jakarta.apache.org/jmeter/usermanual/get-started.html
See Running Jmeter and descriptions of the various scripts that JMeter
provides
See http://www.programmerplanet.org/pages/projects/jmeter-ant-task.php for
an ANT script. ANT integrates with almost all java CI tools.
#2 a bit confused with regards to the "users" and "threads" definitions...
Jmeter only knows about threads and data. The term users is also inaccurate
because in a normal webapp you deal with sessions , not users (e.g. the same
user opens an IE window and a firefox window and logs in , there are two
sessions and hence two virtual users though they have the same login).
Typically an application stores session id in a cookie and in JMeter the
CookieManager is per thread and hence the statement a thread = a session is
normally true. There are exceptions when you dont want this to be the case
and workarounds, but unless you need that , dont bother about it right now.
Typically you want a session to correspond to a unique user , so you
normally send different login data to the thread so that the statement
1thread = 1 session = 1 user is also normally true.

#3 There are forms of errors
a. The webserver refuses any more connections(Typically *503 – Service
Unavailable - server too busy)*
b. The server actually locks up and doesnt allow you to even telnet to it
till the load is removed.
c. The webserver responds too slowly violation any service level agreements
you have.
You increase load by increasing number of threads. Your client machines
running jmeter are normally much less powerful than your server so you need
to run multiple JMeter instances to simulate the load (either as separate
individual instances or as master - slave instances). You also need to be
careful that the error you see is not the client machine refusing to create
any more socket

#4 i'm a bit stumped on how to collect the data.
which?

>netstat -anp|grep :810|wc -l
Should be the number of sockets, not the number of threads. Sockets may not
be closed by the webserver immediately(e.g. tcp_time_wait_interval on
Unix)or a webserver may open different sockets for a series of
requests from the
same client thread(see KeepAlive). This should be atleast equal to the
number of concurrent requests but will probably be more.


>With regards to Listener, is there any way I can just keep the data on each
>server and then grab and parce, do whatever with it AFTER the tests are
>done?
You can write Jmeter results to file ,xml or csv and parse it as you please
(-l  option in the first link)
regards
deepak

On Wed, Mar 10, 2010 at 12:50 PM, William Ottley <williamottley@gmail.com>wrote:

> Hello all,
> I've been doing lots of reading before I decided to send an email.
> I have a few questions i'm hoping someone can answer me, because i'm a bit
> stumped on how to proceed.
>
> #1 does anyone have or know where i can get a good script that starts
> jmeter
> instances (non-gui)?
> #2 a bit confused with regards to the "users" and "threads" definitions...
> #3 how DO I go about trying to find out the maximum threads my webserver
> can
> handle?
> #4 i'm a bit stumped on how to collect the data.
>
> I read somewhere if I wanted to find out how many ACTUAL threads the
> webserver is receiving, use this (on the webserver itself):
> netstat -anp|grep :810|wc -l
>
> Now this is a bit confusing, because at one time I got 44,867 threads.
> This doesn't make sense, because i was using 4 real machines using
> jmeter-server.
> the jmx was set to have 1 thread group, with 2,000 "Number of Threads"
> so in my head, that should be a total of 8,000 threads.
> I have 5 "HTTP Requests" in the thread group, so does this mean 2,000x5 x 4
> jmeter-servers? = 40,000, which does kinda make sense. but still where's
> the
> other 4867 coming from?
>
> With regards to Listener, is there any way I can just keep the data on each
> server and then grab and parce, do whatever with it AFTER the tests are
> done?
> if so (I think i can) what would be a great tool to grap it and manipulate
> the dataset?
>
> thanks for any help!
>
>
> --
> Everything that has, did and will happen in your life, exists now, within
> you (William Ottley)
>
> Every universe is covered by seven layers — earth, water, fire, air, sky,
> the total energy and false ego — each ten times greater than the previous
> one. There are innumerable universes besides this one, and although they
> are
> unlimitedly large, they move about like atoms in You. Therefore You are
> called unlimited (Bhagavata Purana 6.16.37)
>

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