parallel processing - Powershell: Run multiple jobs in parralel and view streaming results from background jobs

Question

Overview

Looking to call a Powershell script that takes in an argument, runs each job in the background, and shows me the verbose output.

Problem I am running into

The script appears to run, but I want to verify this for sure by streaming the results of the background jobs as they are running.

Code

###StartServerUpdates.ps1 Script###

#get list of servers to update from text file and store in array
$servers=get-content c:serverstoupdate.txt

#run all jobs, using multi-threading, in background
ForEach($server in $servers){
  Start-Job -FilePath c:cefcu_itpsscriptsPSPatch.ps1 -ArgumentList $server
}

#Wait for all jobs
Get-Job | Wait-Job

#Get all job results
Get-Job | Receive-Job

What I am currently seeing:

Id              Name            State      HasMoreData     Location             Command                  
--              ----            -----      -----------     --------             -------                  
23              Job23           Running    True            localhost            #patch server ...        
25              Job25           Running    True            localhost            #patch server ...        

What I want to see:

Searching for approved updates ...

Update Found:  Security Update for Windows Server 2003 (KB2807986)
Update Found:  Windows Malicious Software Removal Tool - March 2013 (KB890830)

Download complete.  Installing updates ...

The system must be rebooted to complete installation.
cscript exited on "myServer" with error code 3.
Reboot required...
Waiting for server to reboot (35)

Searching for approved updates ...

There are no updates to install.
cscript exited on "myServer" with error code 2.
Servername "myServer" is fully patched after 2 loops

I want to be able to see the output or store that somewhere so I can refer back to be sure the script ran and see which servers rebooted, etc.

Conclusion:

In the past, I ran the script and it went through updating the servers one at a time and gave me the output I wanted, but when I started doing more servers - this task took too long, which is why I am trying to use background jobs with "Start-Job".

Can anyone help me figure this out, please?

Answer 1

You may take a look at the module SplitPipeline. It it specifically designed for such tasks. The working demo code is:

# import the module (not necessary in PS V3)
Import-Module SplitPipeline

# some servers (from 1 to 10 for the test)
$servers = 1..10

# process servers by parallel pipelines and output results immediately
$servers | Split-Pipeline {process{"processing server $_"; sleep 1}} -Load 1, 1

For your task replace "processing server $_"; sleep 1 (simulates a slow job) with a call to your script and use the variable $_ as input, the current server.

If each job is not processor intensive then increase the parameter Count (the default is processor count) in order to improve performance.