On 09/22/2010 11:15 PM, Brian Devaney wrote: > I have looked around the JMeter documents and elsewhere on the web to > try and fid out if there is a limit to the number of threads available > to JMeter. I have found claims of 1000 threads, 7000 threads and > others, mainly depending on system resources. > > I am testing a web service and I start to run into problems at > approximately 350 user threads. The main error I get is a connection > refused message. To the best of my knowledge, the web service can > handle the number of connections. I have set up several computers all > hitting the web service and the total number of users was well over 600. > I could have tried more, but I ran out of computers.
It depends largely on your Test Plan. The more elements it contains, the fewer threads can be run, since each thread has its own copy of the Test Plan (or so I gathered). My first test plan consistently crashed Java on a machine with 3G max heap space granted to Java, whenever I ran as much as 100 threads. Test Plans should adhere to http://jakarta.apache.org/jmeter/usermanual/best-practices.html#lean_mean as closely as possible, this will maximize your mileage wrt. thread numbers. > What sort of error is generated when JMeter no longer has the resources > to work with more threads. JMeter will run 400 plus threads in one test > group, but the aggregate report shows massive numbers of errors and if I > look at the results in the Tree View, I see many Connection refused > messages. Altering the Rampup time does not seem to improve things > either. Thanks for your help. When Java runs out of memory, it will cease functioning and barf a message about writing a heap dump or somesuch. This may take a while, when your heap is large-ish (which it should be). Connection refused sounds like the problem was either on your server side (which you ruled out already) or somewhere between the Jmeter machine and the server (say, your OS underneath Java limiting the number of open sockets or somesuch, but that should result in yet a different exception). Maybe Jmeter produces more requests than your former test framework. Are you using Timers? Have you tried distributed testing with Jmeter? You should at least try with two worker nodes and find out if the maximum number of total threads remains the same. HTH, Felix --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
