We’re trying to figure out a way to do a capacity test of our servers. We’d like to be able to support in the neighborhood of 32 clients, and we’d like to not require 32 computers to test this. So we’re hoping to run some number of headless clients to do it. Do you guys have a tool for this?
I’ve specifically coded a ‘minimal/headless client’ like that for unit testing (can connect multiple clients from within a single UE4 instance - minimizing overhead/memory-usage), which you can access in *UE4\Engine\Plugins\NetcodeUnitTest* - though it will require some adjustments for you to be able to make it launch multiple clients to the same server, as currently it is setup to launch a single headless client per server.
The primary code for that is in ClientUnitTest.cpp - that class basically encapsulates a single ‘headless client’ - and the easiest method for you to achieve what you want, may be to create 1 unit test class which launches a server and connects a headless client, and then code a 2nd unit test class, which does not launch a server, but instead connects another headless client to the existing server (it would require a big refactoring to get it all working within one unit test - which I will do in the future).
See ‘FTextCrash.cpp’ in Engine\Plugins\NetcodeUnitTest\NUTUnrealEngine4 for a unit test which launches a server and then connects a minimal client - you can use this as a template for the first unit test.
When the first unit test launches the server, the ‘ServerAddress’ variable will contain the address for the server - ‘ExecuteClientUnitTest’ in the first unit test, could be implemented to launch 31 instances of the second unit test class, using:
GEngine->Exec(NULL, TEXT(“UnitTest SecondUnitTestName”));
Then the second unit test class (which should leave out ‘EUnitTestFlags::LaunchServer’ from UnitTestFlags) can - in ‘ExecuteClientUnitTest’ - assign its ServerAddress value to the address of the first unit test, and then you can call ‘ConnectFakeClient’ to connect the minimal/headless client to that address.
Once all of this is done, you can run it using the commandline:
UE4Editor.exe YourGame -run=NetcodeUnitTest.UnitTestCommandlet -unittest=FirstUnitTestName
This unit test tool is recently public, yet still very much ‘in development’, and implementing in the above manner is untested/unsupported, so it may take a bit of messing to get this going - but let me know how you get on, and if it proves useful/difficult
We think this post contains useful information which we would like to share with our public UE4 community. With your approval, we would like to make a copy of this post on the public AnswerHub which includes the discussion but strips out your username and company name. Please let us know if you are okay with this.
Out of curiousity, what’s the current problem with connecting multiple clients from within one test?
Ta Ah it’s just a matter of how it was coded - the ClientUnitTest class itself contains the ‘minimal/headless client’ state/setup, so I’d just need to refactor it to move that into a different class, and a single unit test should be able to do multiple headless clients.
Just hasn’t been needed/useful up until now - but it’s marked down as something to do now.