JMeter issues when running large number of threads

Question

I\'m testing using Apache\'s Jmeter, I\'m simply accessing one page of my companies website and turning up the number of users until it reaches a threshold, the problem is t

Answer 1

For the JVM, if you read hprof it gives you some solutions among which are:

• switch to a 64 bits jvm ( > 6_u25)

• with this you will be able to allocate more Heap (-Xmx) , ensure you have this RAM

• reduce Xss with:

-Xss256k

Then for JMeter, follow best-practices:

• http://jmeter.apache.org/usermanual/best-practices.html
• http://www.ubik-ingenierie.com/blog/jmeter_performance_tuning_tips/

Finally ensure you use last JMeter version.

• Use linux OS preferably

• Tune the TCP stack, limits

Success will depend on your machine power (cpu and memory) and your test plan.

If this is not enough (for 3000 threads it should be OK), you may need to use distributed testing

Answer 2

Increasing the heap size in jmeter.bat works fine set HEAP=-Xms1024m -Xmx1024m

OR you can do something like below if you are using jmeter.sh: JVM_ARGS="-Xms512m -Xmx1024m" jmeter.sh etc.

Answer 3

I had a similar issue and increased the heap size in jmeter.bat to 1024M and that fixed the issue.

set HEAP=-Xms1024m -Xmx1024m

Answer 4

I ran into this same problem and the only solution that helped me is: https://stackoverflow.com/a/26190804/5796780

proper 100k threads on linux:

ulimit -s  256
ulimit -i  120000
echo 120000 > /proc/sys/kernel/threads-max
echo 600000 > /proc/sys/vm/max_map_count
echo 200000 > /proc/sys/kernel/pid_max 

If you don't have root access:

echo 200000 | sudo dd of=/proc/sys/kernel/pid_max

Answer 5

After increasing Xms et Xmx heap size, I had to make my Java run in 64 bits mode. In jmeter.bat :

set JM_LAUNCH=java.exe -d64

Obviously, you need to run a 64 bits OS and have installed Java 64 bits (see https://www.java.com/en/download/manual.jsp)

Answer 6

JVM is simply not capable of running so many threads. And even if it is, JMeter will consume a lot of CPU resources to purely switch contexts. In other words, above some point you are not benchmarking your web application but the client computer, hosting JMeter.

You have few choices:

• experiment with JVM options, e.g. decrease default -Xss512K to something smaller

• run JMeter in a cluster

• use tools taking radically different approach like Gatling