Demo-parallel-foreach

 This requires PowerShell v7

$sub=New-Object System.Collections.ArrayList

$destSubs = [System.Collections.ArrayList]::Synchronized($sub)

$allsubs=@(1,2,3,4,5)

$externalVariable=3

$AllSubs | Sort-Object -Property Name | ForEach-Object -Parallel {

    # Any external variable reference needs to be localized using "using"

    $localVariable = $using:externalVariable

    ($_ -lt $localVariable)

    # Obtain reference to the bag with `using` modifier

    $localCostsVariable = $using:destsubs

    # Add to bag

    $localCostsVariable.Add($_)

}

$destSubs

write-host ""

$sub

# NOTE: many AD object properties won't be visible inside of a parallel script block.

# Need to trigger PS AD adapter driver to populate the result set first

# https://stackoverflow.com/questions/75851412/powershell-foreach-object-parallel-not-all-properties-of-piped-in-object-are-a

#

$users = get-aduser -filter $filter -properties samAccountName,lastLogonTimestamp

#$users=$users|select *    # uncomment this line in order to make below work

$users|foreach -parallel {
   [do something with $_.samAccountName]   # --> this works fine. samAccountName can be read properly
   [do something with $_.lastLogonTimestamp]    # --> this doesn't work. lastLogonTimestamp is always NULL regardless if it is actually populated

}