Powershell runspaces and color output - multithreading

Question

Short issue description:
I need non-interspersed output from additional powershell runspaces that my script spawns. I need to be able to set the color of individual lines in the output.
Long issue description:
I wrote a script to deploy updates to a vendor application on multiple remote servers. Originally the script was meant to only deploy a single update at a time, but I have a new requirement that I now process multiple updates interactively. So I've re-written my script to use runspaces so that I can open sessions on all the servers, initialize them, then for every update the user inputs a runspace is created for each of the initialized sessions and the deployment work is done. I previously used jobs, but had to go to runspaces because you cannot pass a PSSession to a job.
I now have my script working, but the output is less than desirable. The job version had nice output because I could call Receive-Job and get all all my output grouped by thread. Also I could use write-host to log output which allows for colored responses (ie. Red text when updates fail to apply). I have been able to get my runspace version of the job to group output by thread, but only by using write-output. If I use write-host output occurs immediately, causing interspersed output which is unacceptable. Unfortunately write-output does not allow colored output. Setting $host.UI.RawUI.ForegroundColor also does not work because if the output does not happen at the moment in time when the color has been set, the effect does not happen. Since my output won't happen until the end, the $host settings are no longer in play.
Below is a quick demo script to illustrate my woes:
#Runspacing output example. Fix interleaving
cls
#region Setup throttle, pool, iterations
$iterations = 5
$throttleLimit = 2
write-host ('Throttled to ' + $throttleLimit + ' concurrent threads')
$iss = [System.Management.Automation.Runspaces.InitialSessionState]::CreateDefault()
$Pool = [runspacefactory]::CreateRunspacePool(1,$throttleLimit,$iss,$Host)
$Pool.Open()
#endregion
#This works because the console color is set at the time output occurs
$OrigfC = $host.UI.RawUI.ForegroundColor
$host.UI.RawUI.ForegroundColor = 'red'
write-host 'THIS IS RED TEXT!'
start-sleep 2
$host.UI.RawUI.ForegroundColor = $OrigfC
#define code to run off the main thread
$scriptBlock = {
$nl = ([Environment]::NewLine.Chars(0)+[Environment]::NewLine.Chars(1))
#This does not work because output won't occur until after color has been reset
$OrigfC = $host.UI.RawUI.ForegroundColor
$host.UI.RawUI.ForegroundColor = 'yellow'
write-output ($nl + ' TEST: ' + $args[0])
Write-Output (' Some write-output: ' + $args[0])
Start-Sleep 1
write-host (' Some write-host: ' + $args[0]) -ForegroundColor Cyan # notice write-host occurs immediately
Start-Sleep 1
$host.UI.RawUI.ForegroundColor = $OrigfC
}
#Start new runspaces
$threads = #()
$handles = #(for($x = 1; $x -le $iterations; $x++)
{
$powerShell = [PowerShell]::Create().AddScript($scriptBlock).AddParameters(#($x))
$powershell.RunspacePool = $Pool
$powerShell.BeginInvoke()
$threads += $powerShell
})
#Wait for threads to complete
$completedCount = 0
$completed = ($handles | where-object {$_.IsCompleted -eq $true}).count
while($handles.IsCompleted.Contains($false))
{
if($completedCount -ne ($handles | where-object {$_.IsCompleted -eq $true}).count)
{
$completedCount = ($handles | where-object {$_.IsCompleted -eq $true}).count
write-host ('Threads Completed: ' + $completedCount + ' of ' + $iterations)
}
write-host '.' -nonewline
Start-Sleep 1
}
write-host ('Threads Completed: ' + ($handles | where-object {$_.IsCompleted -eq $true}).count + ' of ' + $iterations)
#output from threads
for($z = 0; $z -lt $handles.Count; $z++)
{
$threads[$z].EndInvoke($handles[$z]) #causes output
$threads[$z].Dispose()
$handles[$z] = $null
}
$Pool.Dispose()
The output is below, unless specified the output is in gray:
My goal is to be able to get the lines that say "Some write-output: X" set to one color, and the "TEST: X" set to a different color. Ideas? Please note I'm running from the powershell prompt. You will get different results if you run in the ISE.
Throttled to 2 concurrent threads
THIS IS RED TEXT! #Outputs in Red
. Some write-host: 1 #Outputs in Cyan
Some write-host: 2 #Outputs in Cyan
.Threads Completed: 2 of 5 #Outputs in Yellow
. Some write-host: 3 #Outputs in Cyan
Some write-host: 4 #Outputs in Cyan
.Threads Completed: 4 of 5 #Outputs in Yellow
. Some write-host: 5 #Outputs in Cyan
.Threads Completed: 5 of 5
TEST: 1
Some write-output: 1
TEST: 2
Some write-output: 2
TEST: 3
Some write-output: 3
TEST: 4
Some write-output: 4
TEST: 5
Some write-output: 5
Edit: Adding another example to address Mjolinor's Answer. M, you are correct I can pass sessions to a job; I have oversimplified my example above. Please consider this example below where I am sending a function to the job. If this line ( if(1 -ne 1){MyFunc -ses $args[0]} ) is commented out below, it will run. If the line is not commented out the session (type System.Management.Automation.Runspaces.PSSession) gets converted to a type of Deserialized.System.Management.Automation.Runspaces.PSSession, even though the MyFunc call cannot be hit. I have not been able to figure this out so I started moving towards runspaces. Do you think there is a job oriented solution?
cls
$ses = New-PSSession -ComputerName XXXX
Write-Host ('Outside job: '+$ses.GetType())
$func = {
function MyFunc {
param([parameter(Mandatory=$true)][PSSession]$ses)
Write-Host ('Inside fcn: '+$ses.GetType())
}
}
$scriptBlock = {
Write-Host ('Inside job: '+$args[0].GetType())
if(1 -ne 1){MyFunc -ses $args[0]}
}
Start-Job -InitializationScript $func -ScriptBlock $scriptBlock -Args #($ses) | Out-Null
While (Get-Job -State "Running") { }
Get-Job | Receive-Job
Remove-Job *
Remove-PSSession -Session $ses

Answer 1

I don't quite understand the statement that you can't pass a PSSession to a job. You can run Invoke-Command with both -Session and -AsJob parameters, creating at job targeted to the session.
As far as the coloring conundrum, have you considered using the Verbose or Debug streams for the output you want to be a different color? Powershell should automatically make it a different color depending on the stream it came from.

Answer 2

This gets a bunch easier in Powershell 7, which wasn't yet available when the question was originally asked.
In powershell 7 you can use the foreach-object -parallel {} -asjob command and then fetch the results when all the jobs are completed.
In this example:
There are 5 different jobs with 5 sub-steps
Each step has a 0.5 second delay to demonstrate interleaving
Each job get a color specific to the job
Each step gets a color specific to the step
The output is color coded, and grouped by job
$script = {
foreach ( $Step in 1..5 ) {
write-host "Job $_" -ForegroundColor #{'1'='red';'2'='yellow';'3'='cyan';'4'='magenta';'5'='green'}[[string]$_] -NoNewLine
write-host " Step $Step" -ForegroundColor #{'1'='red';'2'='yellow';'3'='cyan';'4'='magenta';'5'='green'}[[string]$Step]
sleep 0.5
} # next step
} # end script
$Job = 1..5 | ForEach-Object -Parallel $Script -ThrottleLimit 5 -AsJob
$job | Wait-Job | Receive-Job
It should be noted:
The challenge with $job | Wait-Job | Receive-Job is that if any one job hangs, then this command will never return. There are a plethora of posts which describe how to deal with this limitation.
Foreach-object and Foreach-Object -Parallel are two entirely different animals. The former can make calls to predefined functions whereas the later will only have access to what was defined inside the script block.