powershell - 为什么我的运行空间不比顺序方法快？

Question

在本周初创建WPF GUI时，我偶然发现了运行空间。因此，现在我知道它的存在，我希望了解基础知识。我找到以下示例https://gist.github.com/proxb/803fee30f0df244fd850并对其进行了少许(几乎没有)修改。

$w = [system.diagnostics.stopwatch]::startNew()
$Computers = “e”,”f”,”g”,”d”,”c”
$RunspaceCollection = @()
$RunspacePool = [RunspaceFactory]::CreateRunspacePool(1,5)
$RunspacePool.Open()

$ScriptBlock = {
    Param($Computer)
    gci $computer":" -Recurse  | out-file c:\temp\t\$computer.txt

} #/ScriptBlock

Foreach ($Computer in $Computers) {
    $Powershell = [PowerShell]::Create().AddScript($ScriptBlock).AddArgument($Computer)
    $Powershell.RunspacePool = $RunspacePool

    [Collections.Arraylist]$RunspaceCollection += New-Object -TypeName PSObject -Property @{
        Runspace = $PowerShell.BeginInvoke()
        PowerShell = $PowerShell  
    } #/New-Object
$RunspaceCollection
} #/ForEach

$w.elapsed
Write-Host "end"

因此，这遍历了我所有的磁盘，并对它们进行了get-childitem(递归)并将输出保存到txt文件中。
但是相比之下，我几乎没有速度提高:

$w = [system.diagnostics.stopwatch]::startNew()
$Computers = “e”,”f”,”g”,”d”,”c”
Foreach ($Computer in $Computers) {
gci $computer":" -Recurse  | out-file c:\temp\t\$computer.txt
}
$w.elapsed
Write-Host "end"

有人可以解释为什么这样做不快吗？
我可以看到，我在启动脚本后就立即创建了所有txt文件，因此运行空间可以正常工作。

我本以为它会给我比以前更多的时间收获。自动取款机最多只能获得1-3秒的时间，甚至比“旧方法”慢一倍。

Answer 1

因此，看起来用户4c74356b41是正确的。
我早些时候进行了相同的思考过程，并为其添加了3的for循环，但似乎这还不够。如果我添加100的for循环，性能上的差异将变得更加清晰。

$w = [system.diagnostics.stopwatch]::startNew()
    $Computers = “e”,”f”,”d”,”c”
    $RunspaceCollection = @()
    $RunspacePool = [RunspaceFactory]::CreateRunspacePool(1,5)
    $RunspacePool.Open()

    $ScriptBlock = {
        Param($Computer)
    $f = get-date -format "ddmmyyyyfff"
        gci $computer":" -Recurse  | out-file c:\temp\t\$computer$f.txt
    } #/ScriptBlock
for($i = 0; $i -le 100; $i++){
$i
    Foreach ($Computer in $Computers) {
        $Powershell = [PowerShell]::Create().AddScript($ScriptBlock).AddArgument($Computer)
        $Powershell.RunspacePool = $RunspacePool

        [Collections.Arraylist]$RunspaceCollection += New-Object -TypeName PSObject -Property @{
            Runspace = $PowerShell.BeginInvoke()
            PowerShell = $PowerShell  
        } #/New-Object
    } #/ForEach
}

    While($RunspaceCollection) {    
    # Just a simple ForEach loop for each Runspace to get resolved
    Foreach ($Runspace in $RunspaceCollection.ToArray()) {

        # Here's where we actually check if the Runspace has completed
        If ($Runspace.Runspace.IsCompleted) {       
            # Here's where we cleanup our Runspace
            $Runspace.PowerShell.Dispose()
            $RunspaceCollection.Remove($Runspace)       
        } #/If
    } #/ForEach

} #/While

   $w.elapsed
Write-Host "end"

这将需要:

分钟:4
秒:23
毫秒:273

在哪里

$w = [system.diagnostics.stopwatch]::startNew()
$Computers = “e”,”f”,”d”,”c”
for($i = 0; $i -le 100; $i++){
$i
Foreach ($Computer in $Computers) {
    $f = get-date -format "ddmmyyyyfff"
    gci $computer":" -Recurse  | out-file c:\temp\t\$computer$f.txt
    $w.elapsed
}
}
$w.elapsed
Write-Host "end 100 times"

将采取

分钟:9
秒:38
毫秒:932