open vs closed model

I am curious about what i “miss” when using a closed model like this:

`

val scn = scenario(“Scenario”)

.forever(

.exec()

)

setUp(scn.inject(rampUsers(50) over (2 minutes))).maxDuration(4 minutes).protocols(httpConf)

`

contra using an open model like this:

`
val scn = scenario(“Scenario”)

.exec

setUp(scn.inject(constantUsersPerSec(50) during (2 minutes))).protocols(httpConf)

`

What does it mean that the users are recycled in a closed model? Is this kind of the behavior of i.e. LoadRunner?

I have been running a few tests lately using the closed model an I wonder if the results are reliable enough given I have used a closed model? The use case is an android/iphone app with periodes of extreme amounts of unique users accessing it at the same time (during i.e. a campaign for th customer).

Thanks

What does it mean that the users are recycled in a closed model?

It means that a "new" (actually recycled) user can't start (actually loop)
until another one has finished.
As a results, your users are sync'ed.

Is this kind of the behavior of i.e. LoadRunner?

Can't say. Never used LR.

I have been running a few tests lately using the closed model an I wonder
if the results are reliable enough given I have used a closed model? The
use case is an android/iphone app with periodes of extreme amounts of
unique users accessing it at the same time (during i.e. a campaign for th
customer).

Sad news: your results could be pretty badly off because of the user
synchronization mentioned above.
You're hit by what Gil Tene calls coordinated omission. See Nitsan Wakart
<http://psy-lob-saw.blogspot.fr/2015/03/fixing-ycsb-coordinated-omission.html>'s
nice post for more details.
Basically, if your system under starts slowing down, the injector slows
down too, which makes your measures look better than they should.

Your use case is a typical open model: people keep on coming and trying to
use the app, whatever the system under test health.

There's very few use cases for closed model. The only one I can think of in
the web field is a fixed number of client programs with caped connection
pools (eg SOAP/REST clients in a SOA).