我刚刚开始使用 powershell，我想知道为什么我的并行 srcipt 比正常的 foreach 对象脚本更慢？
我的普通 foreachobject 脚本：
function Get-ADUsers { #get all users in nested groups }
function Get-NestedGroupUsers {
param (
[Parameter(Mandatory = $true)][String]$FileName,
[Parameter(Mandatory = $true)][String]$searchFileURL
)
$storageHolder = @()
# $storageHolder | Export-Csv -Path "C:\Users\demandx\Desktop\AD User Lists\$FileName.csv" -NoTypeInformation -Force
$groupList = Get-Content $searchFileURL
$groupList | ForEach-Object {
$allusers = Get-ADUsers -GroupName $_
$storageHolder += $allusers
}
$storageHolder | select ParentGroup, Name, EmployeeNumber, Enabled, LastLogonDate, PasswordLastSet |Export-Csv -Path "C:\Users\demandx\Desktop\$FileName.csv" -NoTypeInformation -Force
}
我的 foreach -parallel 脚本（我将函数存储在 psm1 中，然后在此处导入。）
Function Get-Members {
param (
[Parameter(Mandatory = $true)][String]$FileName,
[Parameter(Mandatory = $true)][String]$searchFileURL
)
$groupList = Get-Content $searchFileURL
$storageHolder = $groupList | ForEach-Object -Parallel {
Import-Module -Name "C:\Users\demandx\Desktop\Get-ADUserMembers.psm1"
Get-ADUserMembers -GroupName $_ | Select-Object ParentGroup, Name, EmployeeNumber, Enabled, LastLogonDate, PasswordLastSet
} -ThrottleLimit 5
$storageHolder | Export-Csv -Path "C:\Users\demandx\Desktop\AD User Lists\$FileName.csv" -NoTypeInformation -Force
}
脚本或我的 get-adusers（获取嵌套组中的所有用户）
function Get-ADUsers {
param (
[Parameter(ValuefromPipeline = $true, mandatory = $true)][String] $GroupName
)
[int]$circular = $null
# result holder
$resultHolder = @()
$table = $null
$nestedmembers = $null
$adgroupname = $null
function Get-ADUsers {
param (
[Parameter(ValuefromPipeline = $true, mandatory = $true)][String] $GroupName
)
[int]$circular = $null
# result holder
$resultHolder = @()
$table = $null
$nestedmembers = $null
$adgroupname = $null
# get members of the group and member of
$ADGroupname = get-adgroup $groupname -properties memberof, members
# list all members as list (no headers) and save to var
$memberof = $adgroupname | select -expand memberof
if ($adgroupname) {
if ($circular) {
$nestedMembers = Get-ADGroupMember -Identity $GroupName -recursive
$circular = $null
}
else {
$nestedMembers = Get-ADGroupMember -Identity $GroupName | sort objectclass -Descending
# if get adgroupmember returns nothing, it uses the members for ordinary getADGroup
if (!($nestedmembers)) {
$unknown = $ADGroupname | select -expand members
if ($unknown) {
$nestedmembers = @()
foreach ($member in $unknown) {
$nestedmembers += get-adobject $member
}
}
}
}
# loops through each member
ForEach($nestedmember in $nestedmembers){
# creates the properties into a custom object.
$Props = @{
Type = $nestedmember.objectclass;
Name = $nestedmember.name;
DisplayName = "";
ParentGroup = $ADgroupname.name;
Enabled = "";
Nesting = $nesting;
DN = $nestedmember.distinguishedname;
Comment = ""
EmployeeNumber = "";
LastLogonDate = "";
PasswordLastSet = "";
}
# if member object is a user
if ($nestedmember.objectclass -eq "user") {
# saves all the properties in the table.
$nestedADMember = get-aduser $nestedmember.Name -properties enabled, displayname, EmployeeNumber, LastLogonDate, PasswordLastSet
$table = new-object psobject -property $props
$table.enabled = $nestedadmember.enabled
$table.name = $nestedadmember.samaccountname
$table.displayname = $nestedadmember.displayname
$table.EmployeeNumber = $nestedadmember.EmployeeNumber
$table.LastLogonDate = $nestedadmember.LastLogonDate
$table.PasswordLastSet = $nestedadmember.PasswordLastSet
#save all in 1 storage
$resultHOlder += $table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment , EmployeeNumber, LastLogonDate, PasswordLastSet
}
# if member object is group
elseif ($nestedmember.objectclass -eq "group") {
$table = new-object psobject -Property $props
# if circular, meaning the groups member of list contains one of its members.
# e.g. if group 2 is a member of group 1 and group 1 is a member of grou 2
if ($memberof -contains $nestedmember.distinguishedname) {
$table.comment = "Circular membership"
$circular = 1
}
# for circular output
#$table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment
#calling function itself
$resultHOlder += Get-ADUsers -GroupName $nestedmember.distinguishedName
}
else {
if ($nestedmember) {
$table = new-object psobject -property $props
$resultHolder += $table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment, EmployeeNumber, LastLogonDate, PasswordLastSet
}
}
}
}
return $resultHOlder
}
function Get-NestedGroupUsers {
param (
[Parameter(Mandatory = $true)][String]$FileName,
[Parameter(Mandatory = $true)][String]$searchFileURL
)
$storageHolder = @()
# $storageHolder | Export-Csv -Path "C:\Users\demandx\Desktop\AD User Lists\$FileName.csv" -NoTypeInformation -Force
$groupList = Get-Content $searchFileURL #| ForEach-Object { $_ }
$groupList | ForEach-Object {
$allusers = Get-ADUsers -GroupName $_
$storageHolder += $allusers
}
$storageHolder | select ParentGroup, Name, EmployeeNumber, Enabled, LastLogonDate, PasswordLastSet |Export-Csv -Path "C:\Users\demandx\Desktop\$FileName.csv" -NoTypeInformation -Force
}
# get members of the group and member of
$ADGroupname = get-adgroup $groupname -properties memberof, members
# list all members as list (no headers) and save to var
$memberof = $adgroupname | select -expand memberof
if ($adgroupname) {
if ($circular) {
$nestedMembers = Get-ADGroupMember -Identity $GroupName -recursive
$circular = $null
}
else {
$nestedMembers = Get-ADGroupMember -Identity $GroupName | sort objectclass -Descending
# if get adgroupmember returns nothing, it uses the members for ordinary getADGroup
if (!($nestedmembers)) {
$unknown = $ADGroupname | select -expand members
if ($unknown) {
$nestedmembers = @()
foreach ($member in $unknown) {
$nestedmembers += get-adobject $member
}
}
}
}
# loops through each member
ForEach($nestedmember in $nestedmembers){
# creates the properties into a custom object.
$Props = @{
Type = $nestedmember.objectclass;
Name = $nestedmember.name;
DisplayName = "";
ParentGroup = $ADgroupname.name;
Enabled = "";
Nesting = $nesting;
DN = $nestedmember.distinguishedname;
Comment = ""
EmployeeNumber = "";
LastLogonDate = "";
PasswordLastSet = "";
}
# if member object is a user
if ($nestedmember.objectclass -eq "user") {
# saves all the properties in the table.
$nestedADMember = get-aduser $nestedmember.Name -properties enabled, displayname, EmployeeNumber, LastLogonDate, PasswordLastSet
$table = new-object psobject -property $props
$table.enabled = $nestedadmember.enabled
$table.name = $nestedadmember.samaccountname
$table.displayname = $nestedadmember.displayname
$table.EmployeeNumber = $nestedadmember.EmployeeNumber
$table.LastLogonDate = $nestedadmember.LastLogonDate
$table.PasswordLastSet = $nestedadmember.PasswordLastSet
#save all in 1 storage
$resultHOlder += $table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment , EmployeeNumber, LastLogonDate, PasswordLastSet
}
# if member object is group
elseif ($nestedmember.objectclass -eq "group") {
$table = new-object psobject -Property $props
# if circular, meaning the groups member of list contains one of its members.
# e.g. if group 2 is a member of group 1 and group 1 is a member of grou 2
if ($memberof -contains $nestedmember.distinguishedname) {
$table.comment = "Circular membership"
$circular = 1
}
# for circular output
#$table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment
#calling function itself
$resultHOlder += Get-ADUsers -GroupName $nestedmember.distinguishedName
}
else {
if ($nestedmember) {
$table = new-object psobject -property $props
$resultHolder += $table | select type, name, displayname, parentgroup, nesting, enabled, dn, comment, EmployeeNumber, LastLogonDate, PasswordLastSet
}
}
}
}
return $resultHOlder
}
平行结果
-------------------------------------------
Days : 0
Hours : 0
Minutes : 1
Seconds : 2
Milliseconds : 283
Ticks : 622833415
TotalDays : 0.000720872008101852
TotalHours : 0.0173009281944444
TotalMinutes : 1.03805569166667
TotalSeconds : 62.2833415
TotalMilliseconds : 62283.3415
非并行结果
-------------------------------------------
Days : 0
Hours : 0
Minutes : 0
Seconds : 35
Milliseconds : 322
Ticks : 353221537
TotalDays : 0.00040882122337963
TotalHours : 0.00981170936111111
TotalMinutes : 0.588702561666667
TotalSeconds : 35.3221537
TotalMilliseconds : 35322.1537
答案 0 :(得分：3)
TLDR：
有3个原因：
ForEach-Object -Parallel 性能，脚本块的处理时间需要明显大于设置线程和环境的时间。Import-Module 会引入开销。ForEach-Object -Parallel 的运行方式与普通的 ForEach-Object 非常不同。
首先，一个普通的 ForEach-Object 在您当前的 PowerShell 线程中运行，可以访问所有变量、加载的内存和流水线。这对于我们运行的所有作业的 98% 都很好，并且 1 秒的执行时间是可以的。在 2% 的情况下，我们有一个超级 CPU 密集型进程，它最大限度地使用单个 CPU 内核并永远运行，或者我们需要在其他执行可以发生时等待响应（例如 API 请求），然后 {{1 }} 是我们需要看的。
并行执行背后的想法是利用您全新的 AMD 锐龙™ Threadripper™ 3990X 和 64 核/128 线程，并将您的进程拆分为单独的“作业”，这些作业可以在多个 CPU 内核和多个线程上运行同时。这可以将您的速度提高几个数量级，例如可能快 128 倍。
为了实现这一点，-Parallel 为您执行的每个脚本块创建一个新的“作业”，并开始在 CPU 内核之间传播作业以执行。当您长时间运行受 CPU 限制的进程时，这很好，但是当您有非常短小的作业时，您就遇到了并行执行的关键，其中设置比实际执行花费的时间更多。 ForEach-Object -Parallel 必须为您运行的每个“作业”完全设置您的环境，例如它必须为每个要运行的作业启动多个新线程和多个新 PowerShell 实例。
为了说明所需的设置时间，如果我们向当前线程写入一次“Hello World”需要 1 毫秒：
ForEach-Object -Parallel并行运行 1 个“Hello World”需要 26 毫秒：
PS C:\> Measure-Command { Write-Host "Hello World" }
Hello World
Seconds : 0
Milliseconds : 1
TotalMilliseconds : 1.9798
这意味着它花费了大约 25 毫秒来启动一个新线程，并设置环境和 1 毫秒的实际工作。
在当前运行的线程上写入 100 次大约需要 83 毫秒：
PS C:\> Measure-Command { 1 | ForEach-Object -Parallel { Write-Host "Hello World" } }
Hello World
Seconds : 0
Milliseconds : 26
TotalMilliseconds : 26.052
使用 PS C:\> Measure-Command { 1..100 | ForEach-Object { Write-Host "Hello World" } }
Hello World
...
Hello World
Hello World
Seconds : 0
Milliseconds : 83
TotalMilliseconds : 83.1846
在 -Parallel 中运行需要 294 毫秒：
-ThrottleLimit 5这表明并行运行对微小的单个操作是如何不利的。但另一方面，如果你有一个需要 1 秒才能运行的东西，你可以开始看看它是如何工作得更好的：
例如运行 5 个进程，每个进程需要 1 秒。首先在单个线程上：
PS C:\> Measure-Command { 1..100 | ForEach-Object -Parallel { Write-Host "Hello World" } -ThrottleLimit 5 }
Hello World
...
Hello World
Hello World
Seconds : 0
Milliseconds : 294
TotalMilliseconds : 294.3205
正如预期的那样，它只需要 5 秒多一点。现在，并行：
PS C:\> Measure-Command { 1..5 | ForEach-Object { Start-Sleep -Seconds 1 } }
Seconds : 5
Milliseconds : 46
TotalSeconds : 5.046348
TotalMilliseconds : 5046.348
它在一秒钟内完成。如果处理时间花费的时间明显多于设置时间，则 PS C:\> Measure-Command { 1..5 | ForEach-Object -Parallel { Start-Sleep -Seconds 1 } -ThrottleLimit 5 }
Seconds : 1
Milliseconds : 73
TotalSeconds : 1.0732423
TotalMilliseconds : 1073.2423
很有用。
此外，在您的情况下，您不仅有额外的设置时间开销，而且加载模块（需要设置新环境）也会显着增加 -Parallel 版本的时间。
例如，让我们在 ForEach-Object -Parallel 脚本中导入一个模块 AzureAD inside 5 次：
ForEach-Object现在有了PS C:\> Measure-Command { 1..5 | ForEach-Object { Import-Module AzureAD } }
Seconds : 0
Milliseconds : 18
TotalSeconds : 0.0185406
TotalMilliseconds : 18.5406
：
ForEach-Object -Parallel我们可以看到有一个显着的区别，因为它必须加载模块 5 次，而不是在线程内只加载一次，然后注意到它仍然加载，而不是重新加载它。