The number of users must be a strictly positive value...

[John Arrowwood]

Am seeing the following exception:

Exception in thread "main" java.lang.IllegalArgumentException: requirement failed: The number of users must be a strictly positive value

       at scala.Predef$.require(Predef.scala:219)

       at io.gatling.core.controller.inject.RampInjection.<init>(InjectionStep.scala:41)

       at io.gatling.core.controller.inject.ConstantRateInjection.<init>(InjectionStep.scala:56)

       at io.gatling.core.controller.inject.InjectionSupport$ConstantRateBuilder.during(InjectionSupport.scala:29)

       at com.cigna.rtde.client.ClientBehavior$class.perHour(ClientBehavior.scala:31)

       at com.cigna.rtde.client.AppsAndActivities$.perHour(AppsAndActivities.scala:11)

       at com.cigna.rtde.client.AppsAndActivities$.behavior(AppsAndActivities.scala:21)

       at com.cigna.rtde.simulation.ProductionSimulation.<init>(ProductionSimulation.scala:16)

       at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

       at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

       at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

       at java.lang.reflect.Constructor.newInstance(Unknown Source)

       at java.lang.Class.newInstance(Unknown Source)

       at io.gatling.app.Gatling.run(Gatling.scala:90)

       at io.gatling.app.Gatling.runIfNecessary(Gatling.scala:73)

       at io.gatling.app.Gatling.start(Gatling.scala:63)

       at io.gatling.app.Gatling$.start(Gatling.scala:51)

       at io.gatling.app.Gatling$.fromArgs(Gatling.scala:43)

       at io.gatling.app.Gatling$.main(Gatling.scala:37)

       at io.gatling.app.Gatling.main(Gatling.scala)

My simulation includes a number of individual scenarios being run concurrently.  I have a "baseline" per-hour rate, and a "multiplier" (so we can evaluate the impact as the traffic grows).  I implemented it something like this:

perHour(multiplier,perHourRate,scenario),...

The definition of perHour is:

 def perHour(

   multiplier: Double,

   rate: Double,

   flow: ScenarioBuilder

 ) =

   flow.inject(

     rampUsersPerSec( 1.0 / 3600.0 )

       to ( rate * multiplier / 3600.0 )

       during ( Test.rampTime )

       randomized,

     constantUsersPerSec( rate * multiplier / 3600.0 )

       during ( Test.duration )

       randomized

   )

Rate is a positive number, in this case "6".  Multiplier is a positive number, "1.0".  So we are passing ( 1.0 * 6.0 / 3600.0 ) or ( 0.001666 ) to the to() method, and the constantUsersPerSec() method.  One of them is not doing the right thing.

NOTE:  I modified "multiplier" to be 10, and the problem goes away.  It appears to be some kind of rounding problem.

[Stéphane LANDELLE]

No, the issue is with your "constantUsersPerSec".

It's actually turned into "rampUser" and it doesn't support injecting less than one user per second.

Stéphane Landelle

Lead developer

slan...@gatling.io

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[John Arrowwood]

That's a fundamental problem for me, unless a workaround can be had.  How do I sustain a low-frequency user injection rate?

[John Arrowwood]

So, I appear to be able to work around it by just using rampUser with the same From and To values.  Could this just be a problem with not using full precision throughout the calculations?  Or some kind of rounding error? Because it seemed to work with 60/3600 but not 6/3600.