More Efficient Bulk Operations with PowerShell Parallelism

Copper Contributor

May 07, 2025

Hello stukey,
Here is another example, a script that we have recently used.

$norusrs = ipcsv "C:\migration\work-3\User4.csv"
 
$norusrs | ForEach-Object -Parallel {
$parconn = try { Get-Mailbox email address removed for privacy reasons -ErrorAction SilentlyContinue } catch {}
         if ($parconn -eq $null) {
          Import-Module -Name ExchangeOnlineManagement -NoClobber
          Write-Host "Connecting in parallel loop"
          Connect-ExchangeOnline -UserPrincipalName email address removed for privacy reasons `
          -ConnectionUri https://outlook.office365.com/powershell?email=email address removed for privacy reasons `
          -ShowBanner:$false -SkipLoadingCmdletHelp:$true `
          -CommandName Get-Mailbox,Set-MailboxFolderPermission
          }
          else {}
          Set-MailboxFolderPermission -Identity ($_.identity+':\calendar') -User default -AccessRights "limiteddetails"
Write-host "Calendar permission set for "$_.identity
  } -ThrottleLimit 5

Soon we will be posting more examples.

Do let us know if you have any further queries or concerns.

Regards,

Indraneel Roy

stukey
Iron Contributor
May 07, 2025
Great, thank you for the additional example.
- niehweune
  Brass Contributor
  May 14, 2025
  Actually, after fiddling around with it for a bit, it turns out that Get-ConnectionInformation does help us, just not as one would expect. The existing EXO connection is readily available inside the threads; the only thing missing is the proxied Cmdlets from Exchange Online (i.e. the ad-hoc module created and loaded when calling Connect-ExchangeOnline isn't loaded in the threads, and module autoloading is of no help here).
  Good news is that Get-ConnectionInformation actually exposes the path to the ad-hoc module, which makes it possible to import it inside the threads and just reuse the existing connection.
  
  A basic example / POC:
  Connect-ExchangeOnline 'a'..'z' | ForEach-Object -Parallel { # Check if we are connected if ($null -eq (Get-ConnectionInformation)) { Throw 'Connect to Exchange Online first' } # Check to see if the module is loaded if (-not (Test-Path function:Get-Mailbox)) { Write-Output 'Loading module' Import-Module (Get-ConnectionInformation).ModuleName -WarningAction SilentlyContinue } Get-Mailbox -ResultSize 10 -Filter ('PrimarySmtpAddress -like "{0}*"' -f $_) -WarningAction SilentlyContinue | Select-Object -ExpandProperty PrimarySmtpAddress }
  So basically, we can reuse the existing connection by simply loading the module inside each of the threads.
  
  On a side note, in this example we even could have skipped module loading altogether and used Get-EXOMailbox instead.

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More Efficient Bulk Operations with PowerShell Parallelism