PowerShell multithreaded script output formatting

Question

I have a script in powershell to hit each server in a list and check if it is online or not. As it was time consuming, I wrote a thread logic to call that script, My script works fine. But I want to split my good/bad servers into two different text files, I cannot hard code it in my script as obviously resource might be used by another thread. If I write it in thread logic my output (both good and bad) will be in the same file. How can I nicely format only desired output?

### Start-MultiThread.ps1 ###
$Servers =Get-Content -Path "C:\Scripts\Servers.txt"

#Start all jobs
ForEach($Server in $Servers){
    Start-Job -FilePath "C:\Scripts\ChkOnline.PS1" -ArgumentList $Server
}

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

#Get all job results
Get-Job | Receive-Job |Out-File -FilePath "C:\Scripts\Output.txt"


##ChkOnline.PS1###

Param($Server = "ServerNameHolder")
$PingStatus= Test-Connection $Server -Quiet

              If ($PingStatus -eq 1)
                        {
                          Return $Server " is online!!"
                        }
            Else
                        {
                          Return $Server " is offline!"
                        }

You can speed this up massively by using "Test-Connection" with the "-Count 1" parameter and value. — Robin
– Robin, Commented Nov 12, 2013 at 20:35

alroc · Accepted Answer · 2013-11-12 19:53:20Z

1

You can do this without starting multiple jobs. Starting multiple jobs incurs memory & processing time overhead and for a task like this, it's more overhead than it's worth.

$Servers = Get-Content -Path "C:\Scripts\Servers.txt"
$results = Test-Connection -ComputerName $servers -Count 1 -ErrorAction silentlycontinue;
$AvailableServers = $results|select -expandproperty address
$OfflineServers = Compare-Object -ReferenceObject $Servers -DifferenceObject $AvailableServers -PassThru;
$AvailableServers | out-file c:\scripts\onlineservers.txt;
$OfflineServers | out-file c:\scripts\offlineservers.txt;

answered Nov 12, 2013 at 19:53

alroc

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4 Comments

alroc Over a year ago

I would still use the technique I posted to filter out off the offline servers. Then, if needed, spawn a job for each server to get your other health data. That job would probably return a custom PSObject that hols all of your health check data (and probably collections of other objects representing it). But "server health check" is a solved problem already - a lot of PowerShell pros/bloggers/MVPs have posted such things, and you should look to those first. You may find that they've not found a need to use jobs, and may have already written a script you can use with minimal changes.

alroc Over a year ago

But before you go writing a script that spawns 100 extra jobs, consider carefully whether you need this to be multithreaded in the first place. It's a good option to have in your back pocket, but don't use it unless you actually need it.

pjc1511 Over a year ago

Thanks for the inputs.The reason why I chose to multithread is I hope to add few more health checks in future, to my script like services health and DB health checks. In that case either I have to dump all data to a single file or I should design my script to give me only failed server/services/DB statuses?

alroc Over a year ago

I really wish you hadn't deleted your comments/questions that I was responding to, as I was responding directly to them. And now you've re-asked the questions, but slightly changing them, changing the context.

js2010 · Accepted Answer · 2019-12-16 15:46:23Z

Using the -asjob parameter (multi-process) makes it very fast. The ones that are up will have a non-null ResponseTime property. Unfortunately, test-connection displays the ResponseTime property as 'Time(ms)' by default. The targetname can be an array.

$servers = 'microsoft.com','yahoo.com'
$a = test-connection $servers -AsJob | Receive-job -Wait -AutoRemoveJob

$a | where responsetime # up

Source        Destination     IPV4Address      IPV6Address  Bytes    Time(ms)
------        -----------     -----------      -----------  -----    --------
DESKTOP-JQ... yahoo.com       98.138.219.231                32       65


$a | where { ! $_.responsetime } # down

Source        Destination     IPV4Address      IPV6Address  Bytes    Time(ms)
------        -----------     -----------      -----------  -----    --------
DESKTOP-JQ... microsoft.com   40.112.72.205                 32

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