How to do concurrent modification testing for grails application - testing

Question

I'd like to run tests that simulate users modifying certain data at the same time for a grails application.
Are there any plug-ins / tools / mechanisms I can use to do this efficiently? They don't have to be grails specific. It should be possible to fire multiple actions in parallel.
I'd prefer to run the tests on functional level (so far I'm using Selenium for other tests) to see the results from the user perspective. Of course this can be done in addition to integration testing if you'd recommend to run concurrent modification tests on integration level as well.

Answer 1

I have used Geb (http://grails.org/plugin/geb/) for this recently. It is a layer on top of WebDriver and Selenium etc.. Its very easy to write a Grails script to act as a user in your app and then just run several instances on different consoles. Geb uses a jQuery style syntax for locating stuff in the DOM which is very cool:
import geb.Browser
import geb.Configuration
includeTargets << grailsScript("_GrailsInit")
target(main: "Do stuff as fast as possible") {
Configuration cfg = new Configuration(baseUrl: "http://localhost:8080/your_app/")
Browser.drive(cfg) {
go "user/login"
$("#login form").with {
email = "someone#somewhere.com"
password = "secret"
_action_Login().click()
}
...
}
}
setDefaultTarget(main)
Just put your script in scripts/YourScript.groovy and then you can do "Grails YourScript" to run it. I tracked down some concurrency issues by just running several of these at full speed. You do need to build a war and deploy it properly as Grails in dev mode is very slow and runs out of permgen space quite quickly.

Answer 2

Just an idea: it seems difficult to make client starts at the same time, but can they wait for each other just before modifying data?
Such as, a client keeps logging its process: "Client x access DATA", "Client x editing DATA" in a file. They also keep looking this log file, to see other clients' progress. Then don't permit a client complete editing a DATA until another client comes in to edit that DATA.

Answer 3

I've found Grinder to be an excellent tool for heavy load testing. Running multiple instances performing the same tests at one time can often uncover concurrency issues in your app that you wouldn't find with normal tests.
If you want to do this within Unit Tests or in-code Integration Tests, you could always spin up multiple threads in code and have them perform the task you're trying to test.

Answer 4

Are you primarily interested in load testing multiple active users, as opposed to those who just have a HttpSession? Solid load testing is predicated on really really good func. testing however. How are your functional tests organized and executed to-day? Grails has a plug-in* for that, too, and it appears to be in the Top of the Pops at the plug-in portal.
Are you attempting to test out how the optimistic locking mechanism performs under load?
If the former use case is the one that means more, it sounds like you may be looking for JUnitPerf. Here is the --> download
*functional-test <1.2.7> -- Functional Testing

Answer 5

WebTest is built on Ant which provides the parallel task. You might be able to use this in conjuction with the Webtest plugin to run some actions in parallel. I've never tried it though.

Answer 6

Have a look at MultithreadedTC. It looks like it could be used to exercise certain interleaving cases where multiple threads are executing your code in ways you consider potentially risky.
I doubt you'll find a convenient way to test specific multithreaded interleaving cases with Selenium because Selenium controls a browser which sends requests to your server. I haven't heard of a way to instrument code for multithreaded interleaving tests when the threads are started as real web requests to a running web server.