PowerShell“foreach-object -Parallel”从循环中获取变量值

Question

如何获取“Foreach-Object”函数/循环之外的“Foreach-Object -Parallel”循环中设置的变量值？在我的示例中，变量

limitReached

最终在

write-host

处没有值。我需要在脚本中使用

While

循环，下面是我正在做的事情的简化版本。

$retries = 2
$secondsDelay = 2
$a = "house"



1..2 | ForEach-Object -Parallel {

    $retryCount = 0
    $ready = $false

    while ($ready -ne $true)
    {      
        if ($a -eq "hello")
        {
            Write-Output ("a is equal ""hello"".")
            $ready = $true                    
        }
        else
        {
            Write-Output ("a is not equal ""hello"".")

            if ($retryCount -ge $using:retries)
            {
                Write-Output ("a is STILL not equal ""hello"".")
                $global:limitReached = $true
                Write-Host "Checking - limitReached value is [$limitReached]"
                return
            }
            else
            {
                Write-Output ("let's give more runs.")`n
                Start-Sleep $using:secondsDelay
                $retryCount++
            }                    
        }
    }        
}

Write-Host "I need this value - limitReached here is [$global:limitReached]"

我期望的结果：

I need this value - limitReached here is [TRUE]

我得到的结果：

Answer 1

您定义全局变量的方式不正确。 您应该在

$a = "house"

下方将其声明为

$limitReached = $false

从代码中删除

$global:

并仅保留变量名称，这样就可以开始了。

这是更新后的代码，提供输出

I need this value - limitReached here is [True]

以及循环输出。

$retries = 2
$secondsDelay = 2
$a = "house"
$limitReached = $false

1..2 | ForEach-Object {
    $retryCount = 0
    $ready = $false

    while ($ready -ne $true)
    {      
        if ($a -eq "hello")
        {
            Write-Output ("a is equal ""hello"".")
            $ready = $true                    
        }
        else
        {
            Write-Output ("a is not equal ""hello"".")

            if ($retryCount -ge $retries)
            {
                Write-Output ("a is STILL not equal ""hello"".")
                $limitReached = $true
                Write-Host "Checking - limitReached value is [$limitReached]"
                return
            }
            else
            {
                Write-Output ("let's give more runs.")`n
                Start-Sleep $secondsDelay
                $retryCount++
            }                    
        }
    }        
}

Write-Host "I need this value - limitReached here is [$limitReached]"

Answer 2

（如果您确实想运行

-Parallel

中的进程）
由于两个项目（

1

和

2

）并行运行（并且

2

nd线程可能首先完成），您希望返回哪个

$limitReached

？ 无论如何，您可以使用

[hashtable]::Synchronized(@{})

类，但最简单的可能就是使用 PowerShell 来检索结果：

$Result = 1..2 |ForEach-Object -Parallel {
    for ($i = 1; $i -le 4 - $_; $i++) {
        Write-Host "Time: $(Get-Date -Format 'HH:mm:ss'), Id: $_, Count: $i"
        Sleep -Seconds $i
    }
    @{
        ID = $_
        Count = $i
        limitReached = $_ -eq 1
    }
}

Time: 14:57:17, Id: 1, Count: 1
Time: 14:57:17, Id: 2, Count: 1
Time: 14:57:18, Id: 2, Count: 2
Time: 14:57:18, Id: 1, Count: 2
Time: 14:57:20, Id: 1, Count: 3

$Result |ConvertTo-Json

[
  {
    "Count": 3,
    "ID": 2,
    "limitReached": false
  },
  {
    "Count": 4,
    "ID": 1,
    "limitReached": true
  }
]

Answer 3

要与 -Parallel 一起使用，我认为您需要 $using: 修饰符以及变量引用

另请参阅 此文档示例结合了 -Parallel 和 $using

例如：

$limitReached = $False
$limitReachedRef = [ref] $limitReached
1..2 | ForEach-Object -Parallel {
    $limitReachedRefCopy = $using:limitReachedRef
    $limitReachedRefCopy.Value = $True
}
$limitReached

输出：

True