Why can't a thread created by PowerShell execute script functions?

Question

I have a script function that calls. net to manipulate word documents. It works. Now I want to create a sub-thread to execute it, and then the main thread decides whether it completes or exceeds the specified time, and ends it after that time. As shown in the code,It does not execute functions in the block of $node code, but instead $task1 executes the cmdlet. Why is that? How can I fulfill my needs?

try{
# $cb is a instance of class，scan is the function I want to invoke.
    $code = { $cb.Scan($PrepareFileName, $NailDirName, $HtmlFileName) }
#    $task1 = { Start-Sleep -Seconds 9; Get-Service }
    $newThread = [PowerShell]::Create().AddScript($code)
    $handleTh = $newThread.BeginInvoke()
    $nTimes = 0;
    do
    {
        $nTimes++;
        if($handleTh.IsCompleted -or $nTimes -gt 10)
        {
          break;  
        }
        Start-Sleep -Milliseconds 500

    } while($true)

    $newThread.EndInvoke($handleTh)
    $newThread.Runspace.Close()
    $newThread.Dispose()

}catch{

}

Isn't that the sentence? $handleTh = $newThread.BeginInvoke() @RossBush — 不知火舞
– 不知火舞, Commented May 8, 2019 at 2:41
New PowerShell's Runspace that you created known nothing about variables in your current Runspace. — user4003407
– user4003407, Commented May 8, 2019 at 3:39
I think you're right. Is there any good way for the new PowerShell to take variables from the parent's runtime? @PetSerAl — 不知火舞
– 不知火舞, Commented May 8, 2019 at 6:29
@不知火舞 Try using PosshRSJob, it lets you handle powershell jobs in different run spaces and can let you access variables from the "parent scope". github.com/proxb/PoshRSJob — David Söderlund
– David Söderlund, Commented May 8, 2019 at 7:23

不知火舞 · Accepted Answer · 2019-05-08 12:00:52Z

1

You need to create a runspaceand it to the PowerShell object. Check this microsoft "tutorial" for using runspaces in a correct manner. The link also explains how to use runspace pools, and script block arguments.

try{
    # $cb is a instance of class，scan is the function I want to invoke.
    $code = { 
        # Update 1, added parameter
        param($cb)
        $cb.Scan($PrepareFileName, $NailDirName, $HtmlFileName) 
    }
    # Create a runspace
    $runspace = [runspacefactory]::CreateRunspace()
    # Update 1, inject parameter
    $newThread = [PowerShell]::Create().AddScript($code).AddParameter(‘cb’,$callback)

    # Add the runspace
    $newThread.Runspace = $runspace
    $runspace.Open()
    $handleTh = $newThread.BeginInvoke()
    $nTimes = 0;
    do
    {
        $nTimes++;
        if($handleTh.IsCompleted -or $nTimes -gt 10)
        {
          break;  
        }
        Start-Sleep -Milliseconds 500

    } while($true)

    $newThread.EndInvoke($handleTh)
    $newThread.Dispose()
}
catch{
}

Hope that helps.

edited May 8, 2019 at 12:00

不知火舞

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answered May 8, 2019 at 6:05

Moerwald

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13 Comments

不知火舞 Over a year ago

Thank you for your answer. I'm doing the same now. But the same result: $handleTh. IsCompleted always equals $true. @Moerwald

不知火舞 Over a year ago

It means that the result of $handleTh.IsCompleted is $true before it has entering the Scan function. @Moerwald

Moerwald Over a year ago

I've done a test. I replace $cb.Scan($PrepareFileName, $NailDirName, $HtmlFileName) with Start-Sleep -Seconds 30. During the sleep time $handleTh.IsCompleted was false. Could it be that $cb is $null or the Scan method return with an error?

Moerwald Over a year ago

Replace $cb.Scan($PrepareFileName, $NailDirName, $HtmlFileName) with Start-Sleep -Seconds 30. Is $handleTh now false ?

不知火舞 Over a year ago

That's my question. There's no problem executing cmdlet, but executing functions won't work. It's perfectly okay to run this function without executing it through [PowerShell]:: Create ().

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