PowerShell hangs when exiting having used a PowerShell runspace pool/runspace

PowerShell Core hangs when exiting and using a PowerShell runspace pool. On Windows PowerShell it exits successfully.

Steps to reproduce

here’s the gist for my code: https://gist.github.com/tylerl0706/2d87a13c6147278bb4e8565585aa9722

Steps:

PS > Add-Type -Path "path/to/TestHttpListener/bin/Debug/netstandard2.0/TestHttpListener.dll"
PS > $app = [TestHttpListener.TestHttpListener]::new()
PS > $app.Start(8081)
PS > Invoke-WebRequest -Uri http://localhost:8081 # VERY IMPORTANT
PS > exit

Expected behavior

PowerShell successfully exists

Actual behavior

PowerShell hangs and doesn’t give the prompt back - this is causing my AppVeyor and Travis builds to fail due to timeout 😦

Environment data

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      6.0.0-beta.8
PSEdition                      Core
GitCommitId                    v6.0.0-beta.8
OS                             Darwin 16.7.0 Darwin Kernel Version 16.7.0: Thu Jun 15 17:36:27 PDT 2017; root:xnu-3789.70.16~2/RELEASE_X86_64
Platform                       Unix
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

[PaulHigin]

@anmenaga, We really need to be able to depend on the CLR to work as advertised. We have other places in the code that relies on the finalizer to work. I’ll investigate more and if this looks like a CLR regression I’ll notify the team.

But for the short term I’ll create a workaround to fix this particular hang problem for RC using our existing cleanup on exit code.

[SteveL-MSFT]

I think I have a simpler repro without using httplistener

PS /Users/steve> $rs = [runspacefactory]::CreateRunspacePool(1,5)                                                                                               
PS /Users/steve> $rs.Open()                                                                                                                                     
PS /Users/steve> $ps = [powershell]::Create()                                                                                                                   
PS /Users/steve> $ps.RunspacePool = $rs                                                                                                                         
PS /Users/steve> $null = $ps.AddScript({1+1})                                                                                                                           
PS /Users/steve> $ps.Invoke()
PS /Users/steve> exit #hangs