Many automated processes we write in Powershell are scheduled on a server somewhere and run periodically.
Sometimes, the script may hang. In my experience, the task scheduler setting “Stop the task if it runs longer than:” rarely works properly when a Powershell script hangs. It either thinks it stopped the task, or is unable to.

This can result in memory hogging runaway Powershell processes, locked log files, concurrent user issues, etc etc.

If you want to prevent that from happening, add this function to your script and call it once at the start of your script. It will kill any Powershell process with the same script name that does not match the running process’s Process ID. It requires Powershell 3+:

function preventDoubleSchedule{
    try{
        $scriptFileName = split-path $MyInvocation.PSCommandPath -Leaf
    }catch{$scriptFileName = $Null}
    try{
        [Array]$psProcesses = @(Get-WmiObject Win32_Process -Filter "name like '%Powershell.exe%' and handle != '$pid'" | where {$_})
    }catch{
        Throw
    }
    if($psProcesses.Count -gt 0){
        foreach($psProcess in $psProcesses){
            if($psProcess.CommandLine -like "*$scriptFileName*" -and $scriptFileName){
                ##we've found a Powershell process that is running this script, but does not have the same process ID, lets try to kill it
                try{
                    Stop-Process -Id $psProcess.Handle -Force -Confirm:$False
                }catch{
                    Throw
                }
            }
        }
    }
}

If you need to use the Invoke-Webrequest on machines that are still running an older Powershell version, this function will help you out.

It sets a script-wide variable called ‘cookiejar’, which will persist any cookies during subsequent calls to this function. You can add customHeaders as a hashtable if you need to. By default the function will also attempt to respond to 401 challenges with the current user credentials.

function JosL-WebRequest{
    Param(
        $uri,
        $method="GET",
        $body,
        $trySSO=1,
        $customHeaders
    )
    if($script:cookiejar -eq $Null){
        $script:cookiejar = New-Object System.Net.CookieContainer     
    }
    $maxAttempts = 3
    $attempts=0
    while($true){
        $attempts++
        try{
            $retVal = @{}
            $request = [System.Net.WebRequest]::Create($uri)
            $request.TimeOut = 5000
            $request.Method = $method
            if($trySSO -eq 1){
                $request.UseDefaultCredentials = $True
            }
            if($customHeaders){
                $customHeaders.Keys | % { 
                    $request.Headers[$_] = $customHeaders.Item($_)
                }
            }
            $request.UserAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 10.0; WOW64; Trident/7.0; .NET4.0C; .NET4.0E)"
            $request.ContentType = "application/x-www-form-urlencoded"
            $request.CookieContainer = $script:cookiejar
            if($method -eq "POST"){
                $body = [byte[]][char[]]$body
                $upStream = $request.GetRequestStream()
                $upStream.Write($body, 0, $body.Length)
                $upStream.Flush()
                $upStream.Close()
            }
            $response = $request.GetResponse()
            $retVal.StatusCode = $response.StatusCode
            $retVal.StatusDescription = $response.StatusDescription
            $retVal.Headers = $response.Headers
            $stream = $response.GetResponseStream()
            $streamReader = [System.IO.StreamReader]($stream)
            $retVal.Content = $streamReader.ReadToEnd()
            $streamReader.Close()
            $response.Close()
            return $retVal
        }catch{
            if($attempts -ge $maxAttempts){Throw}else{sleep -s 2}
        }
    }
}