Strange behaviour of the virtual users

Gatling (Open-Source)
1

Hi.

I am having an issue in my tests. Virtual users are active, but they stop sending requests whithout a pause action, as can be seen in the figure bellow. To check if the requests really stoped, I used wireshark to capture the trafic and I confirm that the trafic goes down like the chart of number of requests per second. First I thought it was a problem in my scenario, but I executed the simple scenario bellow and I got the same problem. Then, I tried to decrease the number of users to check if there was not a performance problem of my computer, and the behavior persisted.

var snc = scenario(“simple”).exec(http(“test”).get(url))

setUp(snc).protocols(httpProtocol).maxDuration(10 minutes)

I changed the base url and I tested in another computer, but the virtual users stop sometimes and I don’t know why.

After all these tests, I thought this can be a bug in Gatling.

I used the version 2.1.7 and the last snapshop 2.2.0 too.

Did anyone have a similar problem?

Thanks.

2

My2cents:

  • full GC
  • C2 kicking in
    You’ll have to monitor your JVM (VisualVM or enable GC logs) and enable the compiler logs.

See https://wikis.oracle.com/display/HotSpotInternals/LogCompilation+overview

Cheers,

3

I followed your advise, but I did not see nothing strange in the log files. I put them attached. The number of requests per second is shown na figura abaixo.

I discarted lack of memory issues, because some of my tests ran with this configuration -Xms8G -Xmx8G -Xmn4G in a machine with 16 GB of RAM.

If you find something in the files or have another ideia, please, let me know.

Thanks.

gc.xml (1.26 KB)

compiler.xml.zip (3.04 MB)

4

Could you run with -XX:+PrintGCDetails so we get the GC times, please?

5

GC log file is attached.

Do you need the compiler log?

gc.xml (3.71 KB)

6

At what time did you see a pause occur when you got this log?
I don’t see anything that bad in the gc logs.
Are you sure you don’t have another process that might be suddenly eating all the CPU?