适用于 PowerShell 5.1 及以上版本，ForEach-Object -Parallel 需要 PowerShell 7
PowerShell 默认是单线程顺序执行的——一个命令完成后再执行下一个。当需要处理数百台服务器、上千个文件或大量 API 请求时，串行执行的等待时间会线性增长。并行处理是解决这类性能瓶颈的关键手段，PowerShell 提供了多种并行方案，从简单到复杂依次为：Start-Job、ForEach-Object -Parallel、Runspace 池。
本文将对比这三种方案，并深入讲解 Runspace 池的高性能用法。
三种并行方案对比 在选择并行方案前，需要了解各方案的特点和适用场景：
方案
最低版本
启动开销
内存占用
适用场景
Start-Job5.1
高（新进程）
高
简单后台任务
ForEach-Object -Parallel7.0
中（新 runspace）
中
快速并行遍历
Runspace 池
5.1
低（线程复用）
低
高性能批量操作
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 $jobs = @ ()$servers = @ ('SRV01' , 'SRV02' , 'SRV03' , 'SRV04' , 'SRV05' )foreach ($server in $servers ) { $jobs += Start-Job -ScriptBlock { param ($srv ) Test-Connection -ComputerName $srv -Count 1 -Quiet Get-Service -ComputerName $srv -Name WinRM | Select-Object Status, Name } -ArgumentList $server } $results = $jobs | Wait-Job | Receive-Job $jobs | Remove-Job $results | Format-Table -AutoSize
执行结果示例：
1 2 3 4 5 6 7 Status Name True WinRMTrue WinRMFalse WinRMTrue WinRMTrue WinRM
ForEach-Object -Parallel（PowerShell 7+） PowerShell 7 引入了 ForEach-Object -Parallel，这是最便捷的并行方案。它在底层使用新的 runspace 来并行执行脚本块，支持控制并发数和超时：
1 2 3 4 5 6 7 8 9 10 11 $servers = 1 ..50 | ForEach-Object { "192.168.1.$_ " }$servers | ForEach-Object -Parallel { $result = Test-Connection -ComputerName $_ -Count 1 -Quiet [PSCustomObject ]@ { Server = $_ Online = $result Time = Get-Date -Format 'HH:mm:ss.fff' } } -ThrottleLimit 10 | Sort-Object Server | Format-Table -AutoSize
执行结果示例：
1 2 3 4 5 6 Server Online Time ------ ------ ---- 192.168.1.1 True 08 :15 :32 .123 192.168.1.2 True 08 :15 :32 .156 192.168.1.3 False 08 :15 :32 .189 ...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 $credential = Get-Credential $logPath = "C:\Logs" 1 ..20 | ForEach-Object -Parallel { $server = "SRV$_ " $session = New-PSSession -ComputerName $server -Credential $using:credential Invoke-Command -Session $session -ScriptBlock { Get-EventLog -LogName System -Newest 10 | Select-Object TimeGenerated, EntryType, Message } | Export-Csv "$using:logPath \$server -events.csv" -NoTypeInformation Remove-PSSession $session Write-Host "完成：$server " } -ThrottleLimit 5 -AsJob | Wait-Job
执行结果示例：
1 2 3 4 完成：SRV1 完成：SRV2 完成：SRV3 ...
注意 ：$using: 语法用于将外部变量传递到并行脚本块中。但 $using: 只能传递可序列化的对象，不能传递活动会话或运行时对象。
Runspace 池高性能并行 Runspace 是 PowerShell 执行环境的最小单元。通过手动创建和管理 runspace，可以实现最低的启动开销和最高的吞吐量。这是处理大规模并行任务的最优方案：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 $maxThreads = 8 $runspacePool = [runspacefactory ]::CreateRunspacePool(1 , $maxThreads )$runspacePool .Open()$servers = @ ('SRV01' , 'SRV02' , 'SRV03' , 'SRV04' , 'SRV05' , 'SRV06' , 'SRV07' , 'SRV08' , 'SRV09' , 'SRV10' ) $scriptBlock = { param ($ServerName ) $startTime = Get-Date Start-Sleep -Milliseconds (Get-Random -Min 100 -Max 500 ) $cpu = Get-Random -Min 10 -Max 95 $mem = Get-Random -Min 30 -Max 85 [PSCustomObject ]@ { Server = $ServerName CPU = $cpu Memory = $mem Status = if ($cpu -gt 80 ) { 'Warning' } else { 'OK' } Duration = ((Get-Date ) - $startTime ).TotalMilliseconds } } $runspaces = @ ()foreach ($server in $servers ) { $powershell = [powershell ]::Create().AddScript($scriptBlock ).AddArgument($server ) $powershell .RunspacePool = $runspacePool $runspaces += [PSCustomObject ]@ { Pipe = $powershell Handle = $powershell .BeginInvoke() Server = $server } } $results = @ ()foreach ($rs in $runspaces ) { $result = $rs .Pipe.EndInvoke($rs .Handle) if ($result ) { $results += $result } $rs .Pipe.Dispose() } $runspacePool .Close()$runspacePool .Dispose()$results | Sort-Object Server | Format-Table -AutoSize
执行结果示例：
1 2 3 4 5 6 7 8 Server CPU Memory Status Duration ------ --- ------ ------ -------- SRV01 45 62 OK 312.45 SRV02 72 58 OK 287.33 SRV03 89 81 Warning 456.12 SRV04 34 45 OK 198.67 SRV05 56 71 OK 234.89 ...
带 进度反馈的 Runspace 长时间运行的并行任务需要进度反馈。通过将 runspace 状态存入字典，可以实时查询进度：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 $maxThreads = 4 $runspacePool = [runspacefactory ]::CreateRunspacePool(1 , $maxThreads )$runspacePool .Open()$tasks = 1 ..20 | ForEach-Object { "Task-$_ " }$scriptBlock = { param ($TaskName ) $totalSteps = 5 for ($step = 1 ; $step -le $totalSteps ; $step ++) { Start-Sleep -Milliseconds (Get-Random -Min 200 -Max 600 ) } [PSCustomObject ]@ { Task = $TaskName Status = 'Completed' Steps = $totalSteps } } $runspaces = [System.Collections.Concurrent.ConcurrentDictionary [string ,object ]]::new()foreach ($task in $tasks ) { $ps = [powershell ]::Create().AddScript($scriptBlock ).AddArgument($task ) $ps .RunspacePool = $runspacePool $handle = $ps .BeginInvoke() $runspaces [$task ] = [PSCustomObject ]@ { Pipe = $ps Handle = $handle } } $completed = 0 $total = $tasks .Countwhile ($completed -lt $total ) { Start-Sleep -Milliseconds 500 foreach ($key in @ ($runspaces .Keys)) { $rs = $runspaces [$key ] if ($rs .Handle.IsCompleted -and -not $rs .Done) { $rs .Done = $true $completed ++ $pct = [math ]::Round($completed / $total * 100 ) Write-Progress -Activity "并行任务执行" ` -Status "$completed / $total 已完成 ($pct %)" ` -PercentComplete $pct } } } $results = @ ()foreach ($key in @ ($runspaces .Keys)) { $rs = $runspaces [$key ] $result = $rs .Pipe.EndInvoke($rs .Handle) if ($result ) { $results += $result } $rs .Pipe.Dispose() } $runspacePool .Close()$runspacePool .Dispose()$results | Format-Table -AutoSize
执行结果示例：
1 2 3 4 5 6 7 Task Status StepsTask -1 Completed 5 Task -2 Completed 5 Task -3 Completed 5 ... Task -20 Completed 5
并行文件处理实战 以下是一个使用 Runspace 池并行处理文件的实用示例——批量计算文件哈希：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 function Get-FileHashParallel param ( [string ]$Path = "C:\Projects" , [int ]$ThrottleLimit = 8 , [string ]$Algorithm = 'SHA256' ) $files = Get-ChildItem -Path $Path -File -Recurse | Where-Object { $_ .Length -gt 1 MB } Write-Host "共 $ ($files .Count) 个文件需要计算哈希" -ForegroundColor Cyan $pool = [runspacefactory ]::CreateRunspacePool(1 , $ThrottleLimit ) $pool .Open() $script = { param ($FilePath , $Algo ) $hash = Get-FileHash -Path $FilePath -Algorithm $Algo [PSCustomObject ]@ { File = $FilePath Hash = $hash .Hash SizeMB = [math ]::Round((Get-Item $FilePath ).Length / 1 MB, 2 ) } } $runspaces = @ () $sw = [System.Diagnostics.Stopwatch ]::StartNew() foreach ($file in $files ) { $ps = [powershell ]::Create().AddScript($script ) $ps .AddArgument($file .FullName).AddArgument($Algorithm ) | Out-Null $ps .RunspacePool = $pool $runspaces += @ { Pipe = $ps ; Handle = $ps .BeginInvoke() } } $results = @ () foreach ($rs in $runspaces ) { $result = $rs .Pipe.EndInvoke($rs .Handle) if ($result ) { $results += $result } $rs .Pipe.Dispose() } $pool .Close() $pool .Dispose() $sw .Stop() Write-Host "`n耗时：$ ($sw .Elapsed.TotalSeconds) 秒" -ForegroundColor Green $results | Format-Table -AutoSize } Get-FileHashParallel -Path "C:\Projects" -ThrottleLimit 8
执行结果示例：
1 2 3 4 5 6 7 8 9 共 42 个文件需要计算哈希 耗时：3.82 秒 File Hash SizeMB ---- ---- ------ C:\Projects\app-v1.0.zip A1B2C3D4E5F6... 125.3 C:\Projects\database-backup.bak F6E5D4C3B2A1... 342.7 C:\Projects\config.json 1234567890AB... 1.2
注意事项
线程安全 ：Runspace 中的代码不应直接修改外部变量或共享状态，应通过返回值传递结果并发数控制 ：ThrottleLimit 或 Runspace 池大小不宜过大，通常设为 CPU 核心数的 2-4 倍错误处理 ：Runspace 中的异常不会自动传播到主线程，需要在脚本块内捕获并通过返回值传递错误信息资源释放 ：使用完毕后必须调用 Dispose() 释放 Runspace 和 PowerShell 对象，避免内存泄漏$using: 限制ForEach-Object -Parallel 中的 $using: 只能传递可序列化的值，不能传递 StreamWriter、数据库连接等运行时对象模块导入 ：每个 Runspace 是独立的执行环境，需要单独导入模块。可以在脚本块开头添加 Import-Module 语句