try to reproduce async choice error revealed in #1378

[forki]

/cc @eiriktsarpalis
I run the sample A LOT and it seems to be failing

[smoothdeveloper]

Failed : FSharp.Core.Unittests.FSharp_Core.Microsoft_FSharp_Control.AsyncModule.Async.Choice repro
Expected: less than or equal to 4
But was: 5
at FSharp.Core.Unittests.FSharp_Core.Microsoft_FSharp_Control.AsyncModule.Async.Choice repro() in C:\projects\visualfsharp-3dtit\src\fsharp\FSharp.Core.Unittests\FSharp.Core\Microsoft.FSharp.Control\AsyncModule.fs:line 438

[eiriktsarpalis]

@forki Could you try adding this?

ThreadPool.SetMinThreads(100,100)

http://stackoverflow.com/questions/17429246/preventing-thread-pool-starvation-with-a-timer-running-at-same-time-as-parallel

[forki]

@KevinRansom this is not compiling on coreclr!? but I have the code under

#if !(FSHARP_CORE_PORTABLE || FSHARP_CORE_NETCORE_PORTABLE)

any ideas why it's still in the coreclr build?

[forki]

Build timed out (after 120 minutes). Marking the build as aborted.

It looks like this actually fixed the test. So let me remove the brute-force test and keep the ThreadPool.SetMinThreads(100,100) for the property-based test. This should remove a bit of flakyness.

[forki]

ok I think this is ready to go in