start-job Run command in parallel and output result as they arrive - powershell

Question

I am trying to get specific KBXXXXXX existence on a list of servers , but once my script one server it takes time and return result and come back and then move to next one . this script works perfectly fine for me .
I want my script to kick off and get-hotfix as job and other process just to collect the results and display them.
$servers = gc .\list.txt
foreach ($server in $servers)
{
$isPatched = (Get-HotFix -ComputerName $server | where HotFixID -eq 'KBxxxxxxx') -ne $null
If ($isPatched)
{
write-host $server + "Exist">> .\patchlist.txt}
Else
{
Write-host $server +"Missing"
$server >> C:\output.txt
}
}
The objective it to make the list execute faster rather than running serially.

Answer 1

With Powershell V2 you can use jobs as in #Andy answer or also in further detail in this link Can Powershell Run Commands in Parallel?
With PowerShell V2 you may also want to check out this script http://gallery.technet.microsoft.com/scriptcenter/Foreach-Parallel-Parallel-a8f3d22b using runspaces
With PowerShell V3 you have the foreach -parallel option.
for example (NB Measure-Command is just there for timing so you could make a comparison)
Workflow Test-My-WF {
param([string[]]$servers)
foreach -parallel ($server in $servers) {
$isPatched = (Get-HotFix -ComputerName $server | where {$_.HotFixID -eq 'KB9s82018'}) -ne $null
If ($isPatched)
{
$server | Out-File -FilePath "c:\temp\_patchlist.txt" -Append
}
Else
{
$server | Out-File -FilePath "c:\temp\_output.txt" -Append
}
}
}
Measure-Command -Expression { Test-My-WF $servers }

Answer 2

For this use PowerShell jobs.
cmdlets:
Get-Job
Receive-Job
Remove-Job
Start-Job
Stop-Job
Wait-Job
Here's an untested example:
$check_hotfix = {
param ($server)
$is_patched = (Get-HotFix -ID 'KBxxxxxxx' -ComputerName $server) -ne $null
if ($is_patched) {
Write-Output ($server + " Exist")
} else {
Write-Output ($server + " Missing")
}
}
foreach ($server in $servers) {
Start-Job -ScriptBlock $check_hotfix -ArgumentList $server | Out-Null
}
Get-Job | Wait-Job | Receive-Job | Set-Content patchlist.txt

Answer 3

Rather than use jobs, use the ability to query multiple computer that's built into the cmdlet. Many of Microsoft's cmdlets, especially those used for system management, take an array of strings as the input for a -Computername parameter. Pass in your list of servers, and the cmdlet will query all of them. Most of the cmdlets that have this ability will query the servers in series, but Invoke-Command will do it in parallel.
I haven't tested this as I don't have Windows booted at the moment, but this should get you started (in sequence).
$servers = gc .\list.txt
$patchedServers = Get-HotFix -ComputerName $servers | where HotFixID -eq 'KBxxxxxxx'|select machinename
$unpatchedServers = compare-object -referenceobject $patchedServers -differenceobject $servers -PassThru
$unpatchedServers |out-file c:\missing.txt;
$patchedServers|out-file c:\patched.txt;
In parallel:
$servers = gc .\list.txt
$patchedServers = invoke-command -computername $servers -scriptblock {Get-HotFix | where HotFixID -eq 'KBxxxxxxx'}|select -expandproperty pscomputername |sort -unique
As before, I don't have the right version of Windows available at the moment to test the above & check the output but it's a starting point.