Jmeter java.lang.OutOfMemoryError: GC overhead lim

问题:

I'm using Jmeter to inject workload to an application deployed on an AWS EC2 instance. The test has to be very huge: it lasts for 10 hours and the workload profile has a bimodal shapes with a pitch of about 2600 requests in 5 minutes. Actually I have one m3.xlarge instance in which the application is deployed and 8 m3.xlarge instances each one running a jmeter instance. With a python script the workload to inject is splitted among the 8 client instances so in example if the original workload as to inject 800 requests, each jmeter instance will inject 100 requests. The full test as I said lasts for 10 hours and is divided into timesteps of 5 min each. Every 5 min a little workload variation is applied. Actually I get from each jmeter instance the java.lang.OutOfMemoryError: GC overhead limit exceeded error immediatly after the test is started and no request arrive to the application. I read a lot online and on stackoverflow, and I concluded the possible mistake could be:

• JMV heap size too low-> I solved setting the following in the jmeter.bat files in each jmeter instance:

  set HEAP=-Xms4g -Xmx4g

  set NEW=-XX:NewSize=4g -XX:MaxNewSize=4g

• some mistakes in the code that results in a continue unuseful usage of the garbage collector. So I remove from my test all the jmeter listeners. In particular I was using TableVisualizer, ViewResultsFullVisualizer, StatVisualizer, and GraphVisualizer.

Anyway the problem persists. I really have no idea about how to solve it. I know 10 hours of test with 2600 pitch request could be a very heavy test, but I think there should be a way to perform this. I'm using EC2 m3.xlarge instance so I could even raise the heap size to 8G if it could be useful, or splitting the workload among even more clients since I'm using spot instances so I will not pay so much more, but since I have already doubled the number of client instance from 4 to 8 in order to solve the problem and is doesn't work I'm a little bit confused and I want to know r suggestions before continue to get more and more resources. Thank you a lot in advance.

回答1:

Your heap settings look wrong: set HEAP=-Xms4g -Xmx4g set NEW=-XX:NewSize=4g -XX:MaxNewSize=4g

Your new is equal to Heap size, this is wrong. Comment NEW part first.

Can you do a ps -eaf|grep java and show the output ?

And also check you respect these recommendations:

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

Finally, show an overview of your Test plan and , number of threads that you start.