Running Parallel SharePoint tasks using powershell workflow

Question

I am not sure if this is supported so looking for some help.

workflow movesites
  {

    Param 
  (
   [Parameter (Mandatory=$true)] $sites,
   [Parameter (Mandatory=$true)] $movedToContentDb

  )
    InlineScript
    {
        Add-PSSnapin "Microsoft.SharePoint.PowerShell" 
    }
    foreach -parallel ($site in $sites)
    {

       $exists = (Get-SPWeb $site.url) -eq $null
          if($exists)
          {
            Write-host "Site doesn't exists"
          }
          else
          {
            Write-host "Moving site $($site.Url) to $contentDbName"
            Get-SPSite $site.url | Move-SPSite -DestinationDatabase $movedToContentDb -Confirm:$false
          }  
    }
  }

Basically, I am trying to invoke few SharePoint cmdlets in Parallel using Powershell Workflows but it seems Powershell Add-in doesn't get loaded at all and function throws error that Get-SPWeb is not recognized which is part of SharePoint powershell snap in.

Another challenge is foreach -parallel cannot be added into inlinescript as its not allowed.

Answer 1

For parallel processes within PowerShell I use "Start-Job". eg:

$ScriptBlock = {
    param($one,$two)
    … do stuff
}
Start-Job -Name "Job" -ScriptBlock $ScriptBlock -ArgumentList $argOne,$ArgTwo| out-null

The script will execute the code within the script block and continue on. There are further commands available to monitor the progress of the job