注意
这里的Powershell指pwsh7，部分新特性无法在5中使用，需要手动调整。
Powershell，有很多人都不喜欢、不理解，但是我挺喜欢的。不过Powershell最大的痛点其实是慢。当你使用各种命令行工具的默认补全命令时，你的启动时间可能会来到十几秒。所以有很多人都觉得这个速度太慢了。这里将要给出一种解决方案，能够成功的把启动时间压缩到500ms以内，并且不阻塞输入。
不要再使用oh-my-posh了，这东西和oh-my-zsh一样都是性能杀手，非常卡顿。欢迎来用Starship，Rust神力还是很神力的。
虽然我觉得大部分人应该没有这种问题，但是鉴于部分应用会自动安装那还是提一下，请务必检查Import-Module的调用，看看有没有不必要的模块被加载了。比如说Azure相关的模块，如果你不需要用到Azure相关的功能，那么就不要加载它们。
大部分cli工具给出的补全命令都是及时输出eval的，比如：
(& uv generate-shell-completion powershell) | Out-String | Invoke-Expression
# 这个 uv 真的是太坏了
这会引入两个性能敏感点：Application调用和管道。
PowerShell scripts that leverage .NET directly and avoid the pipeline tend to be faster than idiomatic PowerShell. Idiomatic PowerShell uses cmdlets and PowerShell functions, often leveraging the pipeline, and resorting to .NET only when necessary.
——PowerShell scripting performance considerations
Powershell不是老旧的基于文本流的shell，powershell的基本设计是基于对象的，所以调用外部进程会引入编解码开销。并且，在运行外部进程的时候会阻塞用户输入。
同时管道越多，性能越差，这是所有shell都有的问题，管道会引入额外的开销。
因此，核心优化点就在于如何避免管道，如何避免调用外部进程。
一些用过zsh-defer的人会对OnIdle比较熟悉，OnIdle在Powershell的触发时机是300ms没有用户输入，所以这可以被用来做后台初始化。一个典型的one-shot例子如下：
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
# Do something
} -MaxTriggerCount 1 -SupportEvent | Out-Null
在接下来的优化过程中，会大量使用OnIdle来做一些非必要的初始化，来达到加速启动的目的。
如何做到不call外部Application就能获得其补全脚本呢？当然是缓存。所以引入了缓存与后台更新机制：
# update scripts
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
$baseDir = Split-Path -Parent $PROFILE
Start-ThreadJob -Name 'completion-cache-update' -ArgumentList $baseDir -ScriptBlock {
param($baseDir)
$ErrorActionPreference = 'Stop'
$locksDir = Join-Path $baseDir 'Locks'
$completionsDir = Join-Path $baseDir 'Completions'
New-Item -ItemType Directory -Force -Path $locksDir, $completionsDir | Out-Null
42 collapsed lines
function Update-CompletionScriptFile {
param(
[Parameter(Mandatory)][string]$CheckCommand,
[Parameter(Mandatory)][string[]]$CheckArgs,
[Parameter(Mandatory)][string]$GenerateCommand,
[Parameter(Mandatory)][string[]]$GenerateArgs,
[Parameter(Mandatory)][string]$OutputFileName
)
$target = Join-Path $completionsDir $OutputFileName
$lockFile = Join-Path $locksDir ($OutputFileName + '.version')
$current = (& $CheckCommand @CheckArgs 2>&1 | Out-String).Trim()
if (-not $current) { throw "Empty version output for $OutputFileName" }
$needsUpdate = $true
if ((Test-Path $lockFile -PathType Leaf) -and (Test-Path $target -PathType Leaf)) {
$prev = (Get-Content $lockFile -Raw).Trim()
if ($prev -eq $current) {
$needsUpdate = $false
}
}
if (-not $needsUpdate) { return }
$body = (& $GenerateCommand @GenerateArgs 2>&1 | Out-String)
if (-not $body.Trim()) { throw "Empty body for $OutputFileName" }
$header = @(
"# generated: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')"
""
) -join [Environment]::NewLine
$tmpTarget = "$target.tmp"
$tmpLock = "$lockFile.tmp"
Set-Content -Path $tmpTarget -Value ($header + $body) -Encoding utf8
Set-Content -Path $tmpLock -Value $current -Encoding utf8
Move-Item -Path $tmpTarget -Destination $target -Force
Move-Item -Path $tmpLock -Destination $lockFile -Force
}
Update-CompletionScriptFile 'starship' @('--version') 'starship' @('init', 'powershell', '--print-full-init') 'starship.ps1'
Update-CompletionScriptFile 'zoxide' @('--version') 'zoxide' @('init', 'powershell') 'zoxide.ps1'
Update-CompletionScriptFile 'pixi' @('--version') 'pixi' @('completion', '--shell', 'powershell') 'pixi.ps1'
Update-CompletionScriptFile 'rustup' @('--version') 'rustup' @('completions', 'powershell') 'rustup.ps1'
Update-CompletionScriptFile 'uv' @('--version') 'uv' @('generate-shell-completion', 'powershell') 'uv.ps1'
Update-CompletionScriptFile 'uvx' @('--version') 'uvx' @('--generate-shell-completion', 'powershell') 'uvx.ps1'
Update-CompletionScriptFile 'sk' @('-V') 'sk' @('--shell', 'power-shell') 'skim.ps1'
} | Out-Null
} -MaxTriggerCount 1 -SupportEvent | Out-Null
这段使用OnIdle one-shot一次触发+ThreadJob后台运行，在后台主动更新缓存的脚本，避免了在启动时调用外部Application来获取补全脚本，同时不阻塞用户输入。
然后补上加载补全脚本的代码，加载的时候直接执行缓存的脚本：
$baseDir = Split-Path -Parent $PROFILE
$locksDir = Join-Path $baseDir 'Locks'
$completionsDir = Join-Path $baseDir 'Completions'
New-Item -ItemType Directory -Force -Path $locksDir, $completionsDir | Out-Null
14 collapsed lines
function Import-CompletionScript {
param(
[Parameter(Mandatory)]
[string]$OutputFileName
)
$target = [System.IO.Path]::Combine($completionsDir, $OutputFileName)
if (-not [System.IO.File]::Exists($target)) {
return $false
}
. $target
return $true
}
Import-CompletionScript 'starship.ps1' | Out-Null
Import-CompletionScript 'zoxide.ps1' | Out-Null
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
Import-CompletionScript 'pixi.ps1' | Out-Null
Import-CompletionScript 'uv.ps1' | Out-Null
Import-CompletionScript 'uvx.ps1' | Out-Null
Import-CompletionScript 'skim.ps1' | Out-Null
Import-CompletionScript 'rustup.ps1' | Out-Null
Import-CompletionScript "$env:HOMEDRIVE$env:HOMEPATH\xmake\scripts\profile-win.ps1" | Out-Null
} -MaxTriggerCount 1 -SupportEvent | Out-Null
这里有两块，starship与zoxide这两个是会更改终端体验的，所以不能够放在OnIdle中加载，不然效果会非常奇怪。其他仅提供补全的都可以延迟加载，当然如果小而美的话也可以不延迟。
$baseDir = Split-Path -Parent $PROFILE
$locksDir = Join-Path $baseDir 'Locks'
$completionsDir = Join-Path $baseDir 'Completions'
New-Item -ItemType Directory -Force -Path $locksDir, $completionsDir | Out-Null
113 collapsed lines
function Import-CompletionScript {
param(
[Parameter(Mandatory)]
[string]$OutputFileName
)
$target = [System.IO.Path]::Combine($completionsDir, $OutputFileName)
if (-not [System.IO.File]::Exists($target)) {
return $false
}
. $target
return $true
}
Import-CompletionScript 'starship.ps1' | Out-Null
Import-CompletionScript 'zoxide.ps1' | Out-Null
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
Import-CompletionScript 'pixi.ps1' | Out-Null
Import-CompletionScript 'uv.ps1' | Out-Null
Import-CompletionScript 'uvx.ps1' | Out-Null
Import-CompletionScript 'skim.ps1' | Out-Null
Import-CompletionScript 'rustup.ps1' | Out-Null
Import-CompletionScript "$env:HOMEDRIVE$env:HOMEPATH\xmake\scripts\profile-win.ps1" | Out-Null
} -MaxTriggerCount 1 -SupportEvent | Out-Null
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
# 新时代的补全方法
# 不生成大量 shell scripts，而是动态向应用程序询问
# 但是目前还没有普及，只能说未来可期
Register-ArgumentCompleter -Native -CommandName winget -ScriptBlock {
param($wordToComplete, $commandAst, $cursorPosition)
[Console]::InputEncoding = [System.Text.UTF8Encoding]::new()
[Console]::OutputEncoding = [System.Text.UTF8Encoding]::new()
$OutputEncoding = [System.Text.UTF8Encoding]::new()
$word = $wordToComplete.Replace('"', '""')
$ast = $commandAst.ToString().Replace('"', '""')
winget complete --word="$word" --commandline "$ast" --position $cursorPosition |
ForEach-Object {
[System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterValue', $_)
}
}
} -MaxTriggerCount 1 -SupportEvent | Out-Null
# update scripts
Register-EngineEvent -SourceIdentifier PowerShell.OnIdle -Action {
$baseDir = Split-Path -Parent $PROFILE
Start-ThreadJob -Name 'completion-cache-update' -ArgumentList $baseDir -ScriptBlock {
param($baseDir)
$ErrorActionPreference = 'Stop'
$locksDir = Join-Path $baseDir 'Locks'
$completionsDir = Join-Path $baseDir 'Completions'
New-Item -ItemType Directory -Force -Path $locksDir, $completionsDir | Out-Null
function Update-CompletionScriptFile {
param(
[Parameter(Mandatory)][string]$CheckCommand,
[Parameter(Mandatory)][string[]]$CheckArgs,
[Parameter(Mandatory)][string]$GenerateCommand,
[Parameter(Mandatory)][string[]]$GenerateArgs,
[Parameter(Mandatory)][string]$OutputFileName
)
$target = Join-Path $completionsDir $OutputFileName
$lockFile = Join-Path $locksDir ($OutputFileName + '.version')
$current = (& $CheckCommand @CheckArgs 2>&1 | Out-String).Trim()
if (-not $current) { throw "Empty version output for $OutputFileName" }
$needsUpdate = $true
if ((Test-Path $lockFile -PathType Leaf) -and (Test-Path $target -PathType Leaf)) {
$prev = (Get-Content $lockFile -Raw).Trim()
if ($prev -eq $current) {
$needsUpdate = $false
}
}
if (-not $needsUpdate) { return }
$body = (& $GenerateCommand @GenerateArgs 2>&1 | Out-String)
if (-not $body.Trim()) { throw "Empty body for $OutputFileName" }
$header = @(
"# generated: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')"
""
) -join [Environment]::NewLine
$tmpTarget = "$target.tmp"
$tmpLock = "$lockFile.tmp"
Set-Content -Path $tmpTarget -Value ($header + $body) -Encoding utf8
Set-Content -Path $tmpLock -Value $current -Encoding utf8
Move-Item -Path $tmpTarget -Destination $target -Force
Move-Item -Path $tmpLock -Destination $lockFile -Force
}
Update-CompletionScriptFile 'starship' @('--version') 'starship' @('init', 'powershell', '--print-full-init') 'starship.ps1'
Update-CompletionScriptFile 'zoxide' @('--version') 'zoxide' @('init', 'powershell') 'zoxide.ps1'
Update-CompletionScriptFile 'pixi' @('--version') 'pixi' @('completion', '--shell', 'powershell') 'pixi.ps1'
Update-CompletionScriptFile 'rustup' @('--version') 'rustup' @('completions', 'powershell') 'rustup.ps1'
Update-CompletionScriptFile 'uv' @('--version') 'uv' @('generate-shell-completion', 'powershell') 'uv.ps1'
Update-CompletionScriptFile 'uvx' @('--version') 'uvx' @('--generate-shell-completion', 'powershell') 'uvx.ps1'
Update-CompletionScriptFile 'sk' @('-V') 'sk' @('--shell', 'power-shell') 'skim.ps1'
} | Out-Null
} -MaxTriggerCount 1 -SupportEvent | Out-Null
使用这种方式后，我再也没有见到过催命500ms+加载提示了。Make Powershell great again！
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