On 11/09/2009, Jakub Białek <ragnor84@gmai...> wrote:
> Obviously JMeter supports much more than 30 threads. But if you use
>  JMeter to simulate e.g. 200 concurrent users to check load and
>  response time of your application then you can use e.g.:
>  - 1 jmeter instance with 200 threads or
>  - 2 jmeter instances with 100 threads each or
>  - 4 jmeter instances with 50 threads each or
>  - 8 jmeter instances with 25 threads each
>  ......
>  The last solution is the best if you want simulate real load that can
>  be generated by 200 real users. The first solution is the worst. I'll
>  explain it below.
>  Let's assume that you have 1 core CPU. Some facts:
>  - at the moment on your cpu can run only one process/thread to
>  simulate multitasking OS gives small amount of time to each
>  process/thread and changes the process/thread context
>  - changing/switching process cost several cpu cycles because cpu
>  registers have to be filled with corresponding data
>  - changing/switching thread is cheaper
>  - not only jmeter runs on your machine also many other
>  application/process bounded to the OS, so jmeter is often dispossess
>  and waiting for cpu cycles
>  - not only workers threads of jmeter runs, also other java threads
>  e.g. GCThread, all those threads compete for cpu
>  - when one thread/process is running others are sleeping/waiting
>  - process/thread can by disposed at any time of execution

These are all true, but:

>  Conclusion:
>  - 200 jmeter threads don't mean 200 concurrent users, load generated
>  by those jmeter instances will be much less than this by 200
>  concurrent real users

That's not a valid conclusion unless JMeter is running out of CPU.

In general, a single JMeter thread can generate *more* load than a
single user, because it can send requests much faster than a human.

>  - more jmeter threads more time spent on switching context, less time
>  used by jmeter worker threads
>  - any worker thread can be disposed (and wait when rest 199 threads
>  will take their cpu time) after receiving answer from server but
>  before calculate time that call to server took so this time will be
>  incorrect
>
>  So if your goal is to simulate as good as possible load generated by
>  many users then use so much jmeter instances (computers) as you can
>  with as less as possible threads on each jmeter instance. Otherwise
>  your results can be far from reality and you can be surprised why your
>  application can't handle with those users even though jmeter stress
>  tests passed.

Again, I disagree with this.

>  If someone is interested in comparison how performance of my
>  application changes depending on jmeter configuration (number of
>  threads and number of instances) I can do that test. I have 10 servers
>  with 2 CPU each and each CPU with 4 core. Those servers can be used as
>  a JMeter clients.
>
>
>  Best regards,
>  Jakub
>
>
>  W dniu 11 września 2009 15:54 użytkownik sebb <sebbaz@gmai...> napisał:
>
> > On 11/09/2009, Jakub Białek <ragnor84@gmai...> wrote:
>  >> How about tomcat is it on linux or windows machine? Make sure that OS
>  >>  doesn't limit the max number of inbound connection.
>  >>
>  >>  Jakub
>  >>
>  >>  BTW. I think that 200 thread on 1 jmeter instance are to many if you
>  >>  don't have cpus that support 64 threads simultaneously ;) . I usually
>  >>  use no more than 50 on 8 core system.
>  >>
>  >
>  > A single JMeter instance can support many more than 50 threads,
>  > depending on the test plan.
>  >
>  >>
>  >>  2009/9/11 Mytho Logic <maumita.majumdar@gmai...>:
>  >>  > Hi,
>  >>  >
>  >>  > I tried with 550 threads in tomcat for 500 concurrent users. But not
>  >>  > succeed.
>  >>  >
>  >>  > Jmeter Client:-
>  >>  > System: Windows XP Professional Verison 2002 SP2
>  >>  > Computer: Intel(R) Core(TM)2 CPU 6300 @ 1.86 Ghz 1.86 GHz, 1.97 GB of RAM
>  >>  >
>  >>  > Jmeter Server:-
>  >>  > System: Windows XP Professional x64 Edition Verison 2003 SP2
>  >>  > Computer: Intel(R) Xeon(R) CPU 5130 @ 2.00 Ghz 2.00 GHz, 8.00 GB of RAM
>  >>  >
>  >>  > Thanks
>  >>  > Maumita
>  >>  >
>  >>  >
>  >>  > 2009/9/11 Jakub Białek <ragnor84@gmai...>
>  >>  >
>  >>  >> If you have 500 (truly) concurrent users then you need at least 500
>  >>  >> threads in tomcat, try with 550 thread.
>  >>  >>
>  >>  >> You run jmeter on windows or linux os?
>  >>  >>
>  >>  >> Best regards,
>  >>  >> Jakub
>  >>  >>
>  >>  >> 2009/9/11 Mytho Logic <maumita.majumdar@gmai...>:
>  >>  >> > Hi,
>  >>  >> >
>  >>  >> > I changed the maxthreads limit in tomcat server.xml to 400 and tried the
>  >>  >> > same testplan again..but few sample requests gets failed and throws
>  >>  >> > exception.
>  >>  >> > what should I do to solve the problem.
>  >>  >> >
>  >>  >> > Exception:-
>  >>  >> >
>  >>  >> > java.net.ConnectException: Connection refused: connect
>  >>  >> >    at java.net.PlainSocketImpl.socketConnect(Native Method)
>  >>  >> >    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
>  >>  >> >    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
>  >>  >> >    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
>  >>  >> >    at java.net.Socket.connect(Socket.java:519)
>  >>  >> >    at java.net.Socket.connect(Socket.java:469)
>  >>  >> >    at sun.net.NetworkClient.doConnect(NetworkClient.java:157)
>  >>  >> >    at sun.net.www.http.HttpClient.openServer(HttpClient.java:382)
>  >>  >> >    at sun.net.www.http.HttpClient.openServer(HttpClient.java:494)
>  >>  >> >    at sun.net.www.http.HttpClient.<init>(HttpClient.java:231)
>  >>  >> >    at sun.net.www.http.HttpClient.New(HttpClient.java:304)
>  >>  >> >    at sun.net.www.http.HttpClient.New(HttpClient.java:316)
>  >>  >> >    at
>  >>  >> >
>  >>  >> sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:817)
>  >>  >> >    at
>  >>  >> >
>  >>  >> sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:769)
>  >>  >> >    at
>  >>  >> >
>  >>  >> sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:694)
>  >>  >> >    at
>  >>  >> >
>  >>  >> org.apache.jmeter.protocol.http.sampler.HTTPSampler.sample(HTTPSampler.java:431)
>  >>  >> >    at
>  >>  >> >
>  >>  >> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1021)
>  >>  >> >    at
>  >>  >> >
>  >>  >> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1007)
>  >>  >> >    at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:290)
>  >>  >> >    at java.lang.Thread.run(Thread.java:595)
>  >>  >> >
>  >>  >> > Thanks
>  >>  >> > Maumita
>  >>  >> >
>  >>  >> >
>  >>  >> > On Fri, Sep 11, 2009 at 3:07 PM, sebb <sebbaz@gmai...> wrote:
>  >>  >> >
>  >>  >> >> On 11/09/2009, Mytho Logic <maumita.majumdar@gmai...> wrote:
>  >>  >> >> > Hi,
>  >>  >> >> >
>  >>  >> >> >  In tomcat server.xml, I changed the maxtheads limit to 300 and kept
>  >>  >> >> >  JAVA_OPTS=-Xms512m -Xmx1024m
>  >>  >> >> >
>  >>  >> >> >  But not succeed.I am getting same "java.net.ConnectException:
>  >>  >> Connection
>  >>  >> >> >  refused: connect" exception. Am I missing anything to change in
>  >>  >> >> server.xml
>  >>  >> >> >  file.
>  >>  >> >> >  The machine on which tomcat server is running has 2 GB RAM.
>  >>  >> >> >
>  >>  >> >> >  Please help on this.
>  >>  >> >>
>  >>  >> >> This appears to be a Tomcat configuaration issue.
>  >>  >> >>
>  >>  >> >> Read the Tomcat documentation carefully, and if that does not answer
>  >>  >> >> your query, then post a question on the Tomcat user list.
>  >>  >> >>
>  >>  >> >> >  Thanks
>  >>  >> >> >  Maumita
>  >>  >> >> >
>  >>  >> >> >
>  >>  >> >> >  On Fri, Sep 11, 2009 at 10:15 AM, Deepak Shetty <shettyd@gmai...>
>  >>  >> >> wrote:
>  >>  >> >> >
>  >>  >> >> >  > Hi
>  >>  >> >> >  > http://tomcat.apache.org/tomcat-5.5-doc/config/http.html
>  >>  >> >> >  > There are three thread related properties in server.xml . You seem
>  >>  >> to
>  >>  >> >> have
>  >>  >> >> >  > run into maxThreads limit
>  >>  >> >> >  > Note that if your server cant handle the load that is a server/OS
>  >>  >> >> problem ,
>  >>  >> >> >  > you are more likely to get help on a tomcat forum. Jmeter is
>  >>  >> >> generating the
>  >>  >> >> >  > load correctly.
>  >>  >> >> >  > regards
>  >>  >> >> >  > deepak
>  >>  >> >> >  >
>  >>  >> >> >  > On Thu, Sep 10, 2009 at 9:38 PM, Mytho Logic <
>  >>  >> >> maumita.majumdar@gmai...
>  >>  >> >> >  > >wrote:
>  >>  >> >> >  >
>  >>  >> >> >  > > Hi,
>  >>  >> >> >  > >
>  >>  >> >> >  > > I am using jmeter version 2.3.2.
>  >>  >> >> >  > > To test my application for 200 concurrent users I have used
>  >>  >> >> distibuted
>  >>  >> >> >  > > testing set up.
>  >>  >> >> >  > > It works fine for 200 users.
>  >>  >> >> >  > > The test plan was -
>  >>  >> >> >  > > 1. 200 concurrent users will first hit the home page
>  >>  >> >> >  > > 2. After that 200 concurrent users will hit the products page
>  >>  >> >> >  > > 3. After that 200 concurrent users will hit the product Detail
>  >>  >> page
>  >>  >> >> >  > >
>  >>  >> >> >  > > For concurrent user setup I have used 'Synchronizing Timer' above
>  >>  >> >> the
>  >>  >> >> >  > > thread
>  >>  >> >> >  > > groups and mentioned 200.
>  >>  >> >> >  > > It works fine and I  got the result.
>  >>  >> >> >  > >
>  >>  >> >> >  > > Setup:-
>  >>  >> >> >  > >
>  >>  >> >> >  > > Tomcat server, Jmeter client and Jmeter server all are in 3
>  >>  >> >> different
>  >>  >> >> >  > > machine.
>  >>  >> >> >  > >
>  >>  >> >> >  > > Tomcat Server
>  >>  >> >> >  > > -------------
>  >>  >> >> >  > > JAVA_OPTS=-Xms1024m -Xmx1024m
>  >>  >> >> >  > >
>  >>  >> >> >  > > Jmeter Client
>  >>  >> >> >  > > -------------
>  >>  >> >> >  > > HEAP=-Xms512m -Xmx1024m
>  >>  >> >> >  > >
>  >>  >> >> >  > > Jmeter Server
>  >>  >> >> >  > > -------------
>  >>  >> >> >  > > HEAP=-Xms512m -Xmx4096m
>  >>  >> >> >  > >
>  >>  >> >> >  > > Using the same configuration and same setup,when i tried for 220
>  >>  >> >> >  > concurrent
>  >>  >> >> >  > > users for few few sample requests I got
>  >>  >> >> >  > > "java.net.ConnectException: Connection refused: connect:
>  >>  >> exception.
>  >>  >> >> >  > > Sometime I succeded for 220 concurrent users without any
>  >>  >> errors.But
>  >>  >> >> next
>  >>  >> >> >  > > time whne I again run the test plan for
>  >>  >> >> >  > > 220 concurrent users I got exception.
>  >>  >> >> >  > >
>  >>  >> >> >  > > What is the reason behind this exception and how can I solve
>  >>  >> this?
>  >>  >> >> >  > > I need to load my application upto 500 concurrent users. Please
>  >>  >> >> suggesst
>  >>  >> >> >  > > how
>  >>  >> >> >  > > can I do this?
>  >>  >> >> >  > >
>  >>  >> >> >  > > This is an urgent requirement.
>  >>  >> >> >  > >
>  >>  >> >> >  > > Thanks
>  >>  >> >> >  > > Maumita
>  >>  >> >> >  > >
>  >>  >> >> >  >
>  >>  >> >> >
>  >>  >> >>
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