Hi. 

This can happen due to overloading your JMeter instances. I'm not sure I am
referring to the right exceptions code, however, I did encounter such
experience when I tried to ask too much of my JMeter instances in a
distributed environment.

If you want to isolate the problem, I can supply you with multiple JMeter
instances already configured. You can try it with let's say 6 strong
machines running a small to medium load and see if the problems is solved.

Take a look at my website, it's  http://www.cloud-intelligence.com/load
http://www.cloud-intelligence.com/load  . If you think this can solve
anything for you, I can create a temporary account and let you test it.

Best,
Alon.


sebb-2-2 wrote:
> 
> On 11/09/2009, Jakub Białek <[email protected]> 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 <[email protected]>
>> napisał:
>>
>> > On 11/09/2009, Jakub Białek <[email protected]> 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 <[email protected]>:
>>  >>  > 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 <[email protected]>
>>  >>  >
>>  >>  >> 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 <[email protected]>:
>>  >>  >> > 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 <[email protected]> wrote:
>>  >>  >> >
>>  >>  >> >> On 11/09/2009, Mytho Logic <[email protected]> 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
>> <[email protected]>
>>  >>  >> >> 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 <
>>  >>  >> >> [email protected]
>>  >>  >> >> >  > >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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>>  >>
>>  >> 
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