Code works interactively, in a PS1 file it does not. to reproduce, open powershell, paste the function and then run get-job to see the task. type get-job | remove-job when done and then put code in a PS1 file, it only runs the first two, then exits.
function RunJobFromQueue
{
if( $queue.Count -gt 0)
{
$cn = $queue.Dequeue()
$j = Start-Job -name $cn -ScriptBlock {param($x); Start-Sleep -Seconds 10;"output - " + $x} -ArgumentList $cn
Register-ObjectEvent -InputObject $j -EventName StateChanged -Action {RunJobFromQueue; Unregister-Event $eventsubscriber.SourceIdentifier; Remove-Job $eventsubscriber.SourceIdentifier } | Out-Null
}
}
$maxConcurrentJobs = 2
$jobInput = "test1", "test2", "test3", "test4", "test5", "test6"
$queue = [System.Collections.Queue]::Synchronized( (New-Object System.Collections.Queue) )
foreach($item in $jobInput) {$queue.Enqueue($item)}
for( $i = 0; $i -lt $maxConcurrentJobs; $i++){RunJobFromQueue}
In my opinion: it fails in script because:
you start script, define function and variables in script scope
script exits once it defines 2 initial jobs
job complete, registered action runs, but your function is not visible to it (defined in script scope) so it fails.
Two options to solve/ work around it:
define RunJobFromQueue function in global scope (function Global:RunJobFromQueue, $global:queue)
dot-source a script (. .\YourScript.ps1)
This works fine interactively, because in that case you define function/ variable in global scope, so -Action can find them just fine.
Related
At [Asynchronous start][1] I had a question about starting a power-shell script asynchronously which creates a form. As answered in that question this can be solved using start-job
eg
Start-Job -ScriptBlock { test NW -NoWarning -Paranoia:2 }
So I have tried to write the Test.PS1 script routine so it re-calls itself with "Start-Job Test -NoSpawn" The switch nospawn then means it runs without a second call. I have tested this with the example code the above line now has to be and it works
Start-Job -ScriptBlock { test NW -NoSpawn -NoWarning -Paranoia:2 }
However I'm struggling to get the parameters from the original command line to passthrough to the job
I have tried creating a string in the correct format , an array , list the arguments manually , I either get repeated arguments being passed or all of the string ending up in the first Parameter $ComputerList -
A summary of the parameters and the attempts are
Param ([string]$ComputerList = 'status\edi.csv',[switch]$NoSpawn,[switch]$NoWarning,[switch]$Debug,[INT]$Paranoia=6)
...... <Snip>
Start-Job -ScriptBlock { test $ComputerList -NoSpawn -NoWarning:$NoWarning -Paranoia:$Paranoia }
Doesn't work due to scope - also switches are wrong way to do this
Start-Job -ScriptBlock { test -NoSpawn $Args } -argumentlist $ComputerList
Insufficent arguments but works - But I think One Argument is possible ?
Start-Job -ScriptBlock { test $Args -NoSpawn } -argumentlist #("-NoWarning:$NoWarning","-ComputerList:$ComputerList","-Paranoia:$Paranoia")
Everything ends up in $ComputerList
Start-Job -ScriptBlock { test $Args -NoSpawn } -argumentlist "-NoWarning:$NoWarning -ComputerList:$ComputerList -Paranoia:$Paranoia"
Everything ends up in $ComputerList
Full code follows
Param ([string]$ComputerList = 'status\edi.csv',[switch]$NoSpawn,[switch]$NoWarning,[switch]$Debug,[INT]$Paranoia=6)
$Log_Paranoia=$Paranoia
If ($Debug) { $debugPreference="Continue"} #enable debug messages if -debug is specified
If ($NoWarning) { $WarningPreference="SilentlyContinue"} #turn off warning messages
function Write-Paranoid($Level, $message) {
$CS=Get-PSCallStack
$Caller = $CS[1]
$Module = "$($Caller.FunctionName)[$($Caller.ScriptLineNumber)]"
$Diff=$level - $Log_Paranoia
$MSG= "$Module($($Level),$($Log_Paranoia)):$message"
if ($level - $Log_Paranoia -le 0 ) {
Write-host $MSG
}
if($Error.Count -gt 0 ) {
$MSG= "$Module($Level)ERROR:$Error[0]"
Write-Error $MSG
}
$error.clear()
}
Function AddStatusBar($form , $Txt) {
Write-Paranoid 10 "Enter"
$statusBar = New-Object System.Windows.Forms.StatusBar
$statusBar.DataBindings.DefaultDataSourceUpdateMode = 0
$statusBar.TabIndex = 4
$statusBar.Size = SDS 428 22
$statusBar.Location = SDP 0 337
$statusBar.Text = $Txt
$form.Controls.Add($statusBar)
$statusBar
Write-Paranoid 10 "Exit"
}
Function Create-Form ($Title)
{
Write-Paranoid 10 "Enter"
$form1 = New-Object System.Windows.Forms.Form
$form1.Text = $Title
$form1.DataBindings.DefaultDataSourceUpdateMode = 0
$form1.ClientSize = SDS 890 359
$form1.StartPosition = 0
$form1.BackColor = [System.Drawing.Color]::FromArgb(255,185,209,234)
$form1
Write-Paranoid 10 "Exit"
}
Function GenerateTestForm
{
Write-Paranoid 10 "Enter"
[reflection.assembly]::loadwithpartialname("System.Drawing") | Out-Null
[reflection.assembly]::loadwithpartialname("System.Windows.Forms") | Out-Null
$Form1 = Create-Form "Test Form"
$Alist = Get-CommandLine
$StatusBar = AddStatusBar $form1 $AList
$form1.ShowDialog() | Out-Null # Suspends calller
Write-Paranoid 10 "Exit"
}
if ($NoSpawn )
{
Write-Paranoid 3 " NoSpawn "
Write-Paranoid 5 "Call GenerateForm"
if ($Test) {
GenerateTestForm
} else {
GenerateTestForm
}
} else {
Write-Paranoid 3 "NOT NoSpawn restarting as job"
# note that test.ps1 is in the path so it will restart this script
# Start-Job -ScriptBlock { test $ComputerList -NoSpawn -NoWarning:$NoWarning -Paranoia:$Paranoia } #Wrong scope
# Start-Job -ScriptBlock { test -NoSpawn $Args } -argumentlist $ComputerList # Insufficent aruments but works - ONLY One Argument possible -
# Start-Job -ScriptBlock { test $Args -NoSpawn } -argumentlist #("-NoWarning:$NoWarning","-ComputerList:$ComputerList","-Paranoia:$Paranoia") # Everything ends up in $ComputerList
# Start-Job -ScriptBlock { test $Args -NoSpawn } -argumentlist "-NoWarning:$NoWarning -ComputerList:$ComputerList -Paranoia:$Paranoia" # Everything ends up in $ComputerList
}
Your problem can be reduced to this:
How can I re-invoke the script at hand as a background job, passing all original arguments (parameter values, including default parameter values) through?
A simplified example:
param (
[string] $ComputerList = 'status\edi.csv',
[switch] $NoSpawn,
[switch] $NoWarning,
[switch] $Debug,
[int] $Paranoia=6
)
if ($NoSpawn) { # already running as a background job.
"I'm now running in the background with the following arguments:"
$PSBoundParameters
} else { # must re-invoke via a background job
# Add *default* parameter values, if necessary, given that
# they're *not* reflected in $PSBoundParameters.
foreach ($paramName in $MyInvocation.MyCommand.Parameters.Keys) {
if (-not $PSBoundParameters.ContainsKey($paramName)) {
$defaultValue = Get-Variable -Scope Local -ValueOnly $paramName
if (-not ($null -eq $defaultValue -or ($defaultValue -is [switch] -and -not $defaultValue))) {
$PSBoundParameters[$paramName] = $defaultValue
}
}
}
# Start a background job that reinvokes this script with the original
# arguments / default values.
Start-Job {
$argsHash = $using:PSBoundParameters
& $using:PSCommandPath -NoSpawn #argsHash
} |
Receive-Job -Wait -AutoRemoveJob
}
Note:
For demonstration purposes, the initial call waits for the re-invocation via a background job to finish, using Receive-Job -Wait -AutoRemoveJob
In your real code, you can simply discard Start-Job's output (a job-information object) with $null = Start-Job { ... }, and then rely on the job getting cleaned up when the caller's session as a whole exits.
The extra code needed to propagate parameter default values is somewhat cumbersome, but necessary, given that the automatic $PSBoundParameters variable does not reflect default values.
GitHub issue #3285 discusses this limitation, and suggests a potential future solution.
I need to initialize a job using the shell. The job will be a delay plus a call to a vbScript. The following code works fine. For my example, the vbScript is just a single line with a MsgBox "Hello world!"
$functions = {
Function execute_vbs {
param ([string]$path_VBScript, [int]$secs)
Start-Sleep -Seconds $secs
cscript /nologo $path_VBScript
}
}
$seconds = 2
Start-Job -InitializationScript $functions -ScriptBlock {execute_vbs -path_VBScript 'C:\Users\[USERNAME]\Desktop\hello_world.vbs' -secs $seconds} -Name MyJob
The problem comes the moment I want to parameterize the vbScript path. (the idea is to do several different calls to some different vbScripts).
When I do this, the command seems to ignore the parameter input. I did other tests with int parameter and they work fine, the problem looks to be only with the string parameters. The following code does not work:
$functions = {
Function execute_vbs {
param ([string]$path_VBScript, [int]$secs)
Start-Sleep -Seconds $secs
cscript /nologo $path_VBScript
}
}
$input = 'C:\Users\[USERNAME]\Desktop\hello_world.vbs'
$seconds = 2
Start-Job -InitializationScript $functions -ScriptBlock {execute_vbs -path_VBScript $input -secs $seconds} -Name MyJob
I've also tried using the [-ArgumentList] command, but it has the same problem.
Any idea?
The problem is that the $input and $seconds variables inside your script block are in a different scope and are effectively different variables to the ones in the main script.
I've modified your script slightly to remove the call to VBScript to make it easier to reproduce here - my example code is:
$functions = {
Function execute_vbs {
param ([string]$path_VBScript, [int]$secs)
Start-Sleep -Seconds $secs
write-output "filename = '$path_VBScript'"
write-output "secs = '$secs'"
}
}
Here's two ways to fix it:
The Using: scope modifier
See https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_scopes?view=powershell-7#the-using-scope-modifier for the full details, but basically:
For any script or command that executes out of session, you need the Using scope modifier to embed variable values from the calling session scope, so that out of session code can access them.
$filename = 'C:\Users\[USERNAME]\Desktop\hello_world.vbs'
$seconds = 2
$job = Start-Job -InitializationScript $functions -ScriptBlock {
execute_vbs -path_VBScript $using:filename -secs $using:seconds
} -Name MyJob
wait-job $job
receive-job $job
# output:
# filename = 'C:\Users\[USERNAME]\Desktop\hello_world.vbs'
# secs = '2'
Note the $using before the variable names inside the script block - this allows you to "inject" the variables from your main script into the scriptblock.
ScriptBlock Parameters
You can define parameters on the script block similar to how you do it with a function, and then provide the values in the -ArgumentList parameter when you invoke Start-Job.
$filename = 'C:\Users\[USERNAME]\Desktop\hello_world.vbs'
$seconds = 2
$job = Start-Job -InitializationScript $functions -ScriptBlock {
param( [string] $f, [int] $s )
execute_vbs -path_VBScript $f -secs $s
} -ArgumentList #($filename, $seconds) -Name MyJob
wait-job $job
receive-job $job
# output:
# filename = 'C:\Users\[USERNAME]\Desktop\hello_world.vbs'
# secs = '2'
``
This lambda function executes as expected:
$WriteServerName = {
param($server)
Write-Host $server
}
$server = "servername"
$WriteServerName.invoke($server)
servername
However, using the same syntax, the following script prompts for credentials and then exits to the command line (running like this: .\ScriptName.ps1 -ConfigFile Chef.config), implying that the lambda functions aren't executing properly (for testing, each should just output the server name).
Why does the former lambda function return the server name, but the ones in the script don't?
Param(
$ConfigFile
)
Function Main {
#Pre-reqs: get credential, load config from file, and define lambda functions.
$jobs = #()
$Credential = Get-Credential
$Username = $Credential.username
$ConvertedPassword = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($Credential.password)
$Password = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($ConvertedPassword)
$Config = Get-Content $ConfigFile -Raw | Out-String | Invoke-Expression
#Define lambda functions
$BootStrap = {
param($Server)
write-host $server
}
$RunChefClient = {
param($Server)
write-host $server
}
$SetEnvironment = {
param($Server)
write-host $server
}
#Create bootstrap job for each server and pass lambda functions to Scriptblock for execution.
if(($Username -ne $null) -and ($Password -ne $null))
{
ForEach($HashTable in $Config)
{
$Server = $HashTable.Server
$Roles = $HashTable.Roles
$Tags = $HashTable.Tags
$Environment = $HashTable.Environment
$ScriptBlock = {
param ($Server,$BootStrap,$RunChefClient,$SetEnvironment)
$BootStrap.invoke($Server)
$RunChefClient.invoke($Server)
$SetEnvironment.invoke($Server)
}
$Jobs += Start-Job -ScriptBlock $ScriptBlock -ArgumentList #($Server,$BootStrap,$RunChefClient,$SetEnvironment)
}
}
else {Write-Host "Username or password is missing, exiting..." -ForegroundColor Red; exit}
}
Main
Without testing, I am going to go ahead and say it's because you are putting your scriptblock executions in PowerShell Jobs and then not doing anything with them. When you start a job, it starts a new PowerShell instance and executes the code you give it along with the parameters you give it. Once it completes, the completed PSRemotingJob object sits there and does nothing until you actually do something with it.
In your code, all the jobs you start are assigned to the $Jobs variable. You can also get all your running jobs with Get-Job:
Get-Job -State Running
If you want to get any of the data returned from your jobs, you'll have to use Receive-Job
# Either
$Jobs | Receive-Job
# Or
Get-Job -State Running | Receive-Job
I have a problem in running the below Powershell script in console.
function startMonitor {
$null = Register-ObjectEvent -InputObject ([Microsoft.Win32.SystemEvents]) -EventName "SessionSwitch" -Action {
switch($event.SourceEventArgs.Reason) {
'SessionLock'
{
---------do something----
}
'SessionUnlock'
{
--------do something----
}
}
}
}
startMonitor
When I run this in powershell ISE it works fine and output is as expected. When the session is locked or unlocked, output is generated perfectly.
But I want to run this as a script that starts up during logon.
I put this script in the startup folder as
powershell.exe -noexit -windowstyle hidden "E:\sources\lock.ps1"
The script runs fine. But, it does not generate the output (the other functions in this code generates output properly, except this function). When I try the command (without the switch -windowstyle):
Get-EventSubscriber
Shows that event is registered.
How do I run this script using the powershell.exe -noexit?
I am unable to use task scheduler for this purpose because of limitations in my environment.
In order to run in background you have to keep it within a loop and check for events, test with this little example...
[System.Reflection.Assembly]::LoadWithPartialName("System.Diagnostics")
# ------ init ------
function Start-mySession {
$null = Register-ObjectEvent -InputObject ([Microsoft.Win32.SystemEvents]) -EventName "SessionSwitch" -Action {
add-Type -AssemblyName System.Speech
$synthesizer = New-Object -TypeName System.Speech.Synthesis.SpeechSynthesizer
switch($event.SourceEventArgs.Reason) {
'SessionLock' { $synthesizer.Speak("Lock!") }
'SessionUnlock' { $synthesizer.Speak("Unlock!") }
}
}
}
# ------ stop ------
function End-mySession {
$events = Get-EventSubscriber | Where-Object { $_.SourceObject -eq [Microsoft.Win32.SystemEvents] }
$jobs = $events | Select-Object -ExpandProperty Action
$events | Unregister-Event
$jobs | Remove-Job
}
# ===== keep process in alive for 10 hours =====
[TimeSpan]$GLOBAL:timeout = new-timespan -Hours 10
$GLOBAL:sw = [diagnostics.stopwatch]::StartNew()
while ($GLOBAL:sw.elapsed -lt $GLOBAL:timeout){
[Array]$GLOBAL:XX_DEBUG_INFO += "DEBUG: initialize debug!"
# Loop
Start-mySession
start-sleep -seconds 10
#.. do something, or check results
End-mySession
}
# teardown after timeout
Write-Output "INFO: $( get-date -format "yyyy-MM-dd:HH:mm:ss" ) : $env:USERNAME : Timeout (logout/timout)"
End-mySession
I saw this question and this question but couldn't find solution to my problem.
So here is the situation:
I have two functions DoWork and DisplayMessage in a script (.ps1) file. Here is the code:
### START OF SCRIPT ###
function DoWork
{
$event = Register-EngineEvent -SourceIdentifier NewMessage -Action {
DisplayMessage($event.MessageData)
}
$scriptBlock = {
Register-EngineEvent -SourceIdentifier NewMessage -Forward
$message = "Starting work"
$null = New-Event -SourceIdentifier NewMessage -MessageData $message
### DO SOME WORK HERE ###
$message = "Ending work"
$null = New-Event -SourceIdentifier NewMessage -MessageData $message
Unregister-Event -SourceIdentifier NewMessage
}
DisplayMessage("Processing Starts")
$array = #(1,2,3)
foreach ($a in $array)
{
Start-Job -Name "DoActualWork" $ScriptBlock -ArgumentList $array | Out-Null
}
#$jobs = Get-Job -Name "DoActualWork"
While (Get-Job -Name "DoActualWork" | where { $_.State -eq "Running" } )
{
Start-Sleep 1
}
DisplayMessage("Processing Ends")
Get-Job -Name "DoActualWork" | Receive-Job
}
function DisplayMessage([string]$message)
{
Write-Host $message -ForegroundColor Red
}
DoWork
### END OF SCRIPT ###
I am creating 3 background jobs (using $array with 3 elements) and using event to pass messages from background jobs to the host. I would expect the powershell host to display "Processing Starts" and "Processing Ends" 1 time and "Starting work" and "Ending work" 3 times each. But instead I am not getting "Starting work"/"Ending work" displayed in console.
Event is also treated as a job in powershell, so when I do Get-Job, I can see following error associated with the event job:
{The term 'DisplayMessage' is not recognized as the name of a cmdlet,
function, script file, or operable program. Check the spelling of the
name, or if a path was included, verify that the path is correct and
try again.}
My question: How can we reuse (or reference) a function (DisplayMessage in my case) defined in the same script from where I am calling Start-Job? Is it possible?
I know we can use -InitializationScript to pass functions/modules to Start-Job, but I do not want to write DisplayMessage function twice, one in script and another in InitializationScript.
An easy way to include local functions in a background job:
$init=[scriptblock]::create(#"
function DoWork {$function:DoWork}
"#)
Start-Job -Name "DoActualWork" $ScriptBlock -ArgumentList $array -InitializationScript $init | Out-Null
Background jobs are run in a seperate process, so the jobs you create with Start-Job can not interact with functions unless you include them in the $scriptblock.
Even if you included the function in the $scripblock, Write-Host would not output it's content to the console until you used Get-Job | Receive-Job to recieve the jobs result.
EDIT The problem is that your DisplayMessage function is in a local script-scope while your eventhandler runs in a different parent scope(like global which is the session scope), so it can't find your function. If you create the function in the global scope and call it from the global scope, it will work.
I've modified your script to do this now. I've also modified to scriptblock and unregistered the events when the script is done so you won't get 10x messages when you run the script multiple times :-)
Untitled1.ps1
function DoWork
{
$event = Register-EngineEvent -SourceIdentifier NewMessage -Action {
global:DisplayMessage $event.MessageData
}
$scriptBlock = {
Register-EngineEvent -SourceIdentifier NewMessage -Forward
$message = "Starting work $args"
$null = New-Event -SourceIdentifier NewMessage -MessageData $message
### DO SOME WORK HERE ###
$message = "Ending work $args"
$null = New-Event -SourceIdentifier NewMessage -MessageData $message
Unregister-Event -SourceIdentifier NewMessage
}
DisplayMessage("Processing Starts")
$array = #(1,2,3)
foreach ($a in $array)
{
Start-Job -Name "DoActualWork" $ScriptBlock -ArgumentList $a | Out-Null
}
#$jobs = Get-Job -Name "DoActualWork"
While (Get-Job -Name "DoActualWork" | where { $_.State -eq "Running" } )
{
Start-Sleep 1
}
DisplayMessage("Processing Ends")
#Get-Job -Name "DoActualWork" | Receive-Job
}
function global:DisplayMessage([string]$message)
{
Write-Host $message -ForegroundColor Red
}
DoWork
Get-EventSubscriber | Unregister-Event
Test
PS > .\Untitled1.ps1
Processing Starts
Starting work 1
Starting work 2
Ending work 1
Ending work 2
Starting work 3
Ending work 3
Processing Ends
I got it to work as follows;
function CreateTable {
$table = "" | select ServerName, ExitCode, ProcessID, StartMode, State, Status, Comment
$table
}
$init=[scriptblock]::create(#"
function CreateTable {$function:createtable}
"#)