Remote PSSession Tasks

run_task_on_remote_servers_in_parallel.ps1

# This is a scriptblock that will be invoked on the remote computer. This is 
# just dummy code that gets the computers hostname from the global built in 
# eniorment variable $env.
$RemoteTask = {
    param(
        [datetime]$Start
    )

    # pause remote script execition until the specified start time.
    # you can use this to loosely sync jobs execution.
    $SleepDuration = New-TimeSpan -Start $(get-date) -End $Start
    Start-Sleep -Milliseconds $SleepDuration.TotalMilliseconds

    # anything in this block will be invoked on the remote computers
    Write-Host "Hello from $($env:COMPUTERNAME)!"
}

# An array of all the computer names. Computer names must be valid. ip address
# are also valid
$Computers = @(
  'COMPUTER1'
  'COMPUTER2'
)

# This script assumses that powershell remoting is enabled on all computers.
$Sessions = New-PSSession -ComputerName $Computers

# A dynamic array to store all the jobs
[system.collections.arraylist]$jobs = @()

# jobs will use this time to sync there execution. this assumes that it will 
# take less then 30 second to startup all the jobs.
$JobStartTime = $(get-date).AddSeconds(30)

# Normally the Invoke-Command will wait until the scriptbock finishes before 
# moving to the next session in the foreach loop, but the -AsJob parameter 
# will convert the command into a powershell job, which will allow the loop 
# to continue as soon as the job starts.
# https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_jobs
foreach($Session in $Sessions){
    $jobs += Invoke-Command -Session $Session -ScriptBlock $RemoteTask -ArgumentList $JobStartTime -AsJob
}

# piping jobs to wait-job will cause the script to wait for all remote jobs to finish.
$jobs | Wait-Job | Out-Null 

# once all jobs are finished you can receive the output from the jobs.
# in this case it will be the output of Write-Host from the Remote Task.
foreach($job in $jobs){
    $RemoteOutput = $job | Receive-Job
    Write-Host $RemoteOutput
}

# clean up. just be sure the jobs are finished...
Disconnect-PSSession -Session $Sessions | Out-Null

Alternatively the script could use get-job instead of wait-job to check the status of each job, then use receive-job on jobs that have completed.