I had to build my own extension to support testing of one of our internal components.
The extension supports stateful, coordinated consumers pulling data from a proprietary system.
My implementation is essentially an implementation of an ExitableAction, where execute(..) creates a future on a dedicated ExecutionContext (with an arbitrarily high number of threads).
The future completion has some very basic throttle logic and calls next ! session.
if (throttled) {
coreComponents.throttler.throttle(session.scenario, () => next ! session)
} else {
next ! session
}
One of the coordination actions needs to take place on all the consumers, and cannot complete until confirmation is received from all the consumers.
When I increase the number of consumers (past 32), I see 32 consumers respond to this request correctly, and consumers in excess of 32 do nothing… until the previous 32 complete.
This breaks our test, as I cannot increase the number of coordinated consumers beyond 32.
The behaviour that I’m seeing only manifests when there are more than 32 users running a scenario that use this action…
My server has 32 cores, which may/may-not be a coincidence; I have not tested it on a machine with fewer cores.
Its also interesting to note that multiple (different) scenarios with a total of more than 32 users’ do not have this problem; it seems to be limited when I have > 32 users for the same scenario.
Is there any limit in gatling that would prevent more than some number of scenario-users’ being active, or waiting on a action-response simultaneously?
If so… how do I tweak it?
Thank you in advance.
- Jon