PowerShell foreach 文件夹中的文件使用大量内存

Question

我对 PowerShell 和编程还很陌生，所以我确信这段代码可以进一步优化。

然而，我对这段代码最大的问题是它将来自 foreach 循环的数据放入内存中。防止这种情况的最佳方法是什么？

我开始使用在此处找到的脚本重写此脚本：PowerShell: delete files older than x days

编辑：哦，顺便说一下，每个 TargetFolder 中大约有 60 000~ 个文件。

## Set Window Title
$title = $Host.UI.RawUI.WindowTitle
$titdef = $title
$Host.UI.RawUI.WindowTitle = "Checking files. Do NOT close " + "($title)"

## Debug (0=Nothing, 1=Extended log, 2=Extended log+Screen)
$Debug = "2"

## Log file
$log = "C:\status\status.txt"
Add-Content $log "nul"

## Clear log before adding new data 
Remove-Item $log

## Folders to check
$TargetFolder1 = “\\server\c$\BiztalkProjects\UDC\output\ume”
$TargetFolder2 = “\\server\c$\BiztalkProjects\UDC\output\upp”

## Required stuff
$Now = Get-Date
$Days = “2”
$TwoDays = $Now.AddDays(-$Days)
$Folder1 = get-childitem $TargetFolder1 -include *
$Folder2 = get-childitem $TargetFolder2 -include *

## Window Message
"Checking for files newer than $Days days in:"
"$TargetFolder1"
"$TargetFolder2"
""
"This may take 5-15 minutes . . . (Will commit about 250MB~ RAM during the period)"

## Reset variable $OK to "0"
$OK = 0

if ($Debug -eq "2") {"Check1"}
foreach ($File in $Folder1) {
    $FileLastWrite = $File.LastWriteTime
    if ($File.LastWriteTime -le $TwoDays) {
        $OK = $OK + "0"
        if ($Debug -eq "2") {
            "OK + 0 (=$OK) $File ($FileLastWrite)"
            }
    } else {
        $OK = $OK + "1"
        if ($Debug -eq "2") {
            "OK + 1 (=$OK) $File ($FileLastWrite)" 
            }
    }
}
if ($Debug -eq "2") {"Check2"}
foreach ($File in $Folder2) {
    $FileLastWrite = $File.LastWriteTime
    if ($File.LastWriteTime -le $TwoDays) {
        $OK = $OK + "0"
        if ($Debug -eq "2") {
            "OK + 0 (=$OK) $File ($FileLastWrite)"
            }
    } else {
        $OK = $OK + "1"
        if ($Debug -eq "2") {
            "OK + 1 (=$OK) $File ($FileLastWrite)" 
            }
    }
}
if ($OK -gt "0") {
    if ($Debug -eq "2") {
        ""
        "Found $OK file(s) newer than $Days days"
        }
    Add-Content $log "OK"
    if ($Debug -ge "1") {
        Add-Content $log "Found $OK file(s) newer than $Days days"
        }
    }
    else {
        if ($Debug -eq "2") {
        ""
        "Found $OK file(s) newer than $Days days"
        }
    Add-Content $log "Error"
    if ($Debug -ge "1") {
        Add-Content $log "Found $OK file(s) newer than $Days days"
        }
    }
$Host.UI.RawUI.WindowTitle = $titdef

此版本有效。感谢所有帮助过的人！

## Set Window Title
$title = $Host.UI.RawUI.WindowTitle
$titdef = $title
$Host.UI.RawUI.WindowTitle = "Checking files. Do NOT close " + "($title)"

## Debug (0=Nothing, 1=Extended log, 2=Extended log+Screen)
$Debug = "2"

## Log file
$log = "C:\status\status.txt"
Add-Content $log "nul"

## Clear log before adding new data 
Remove-Item $log

## Folders to check
$TargetFolder1 = “\\server\c$\BiztalkProjects\UDC\output\ume”
$TargetFolder2 = “\\server\c$\BiztalkProjects\UDC\output\upp”

## Required stuff
$Now = Get-Date
$Days = “2”
$TwoDays = $Now.AddDays(-$Days)

## Window Message
"Checking for files newer than $Days days in:"
"$TargetFolder1"
"$TargetFolder2"
""
"This may take 5-15 minutes . . ."

## Reset variable $OK to "0"
$OK = 0

get-childitem $TargetFolder1,$TargetFolder2 -filter *.xml |where-object {
    $FileLastWrite = $_.LastWriteTime
    if ($FileLastWrite -le $TwoDays) {
        $OK = $OK + "0"
    } else {
        $OK = $OK + "1"
    }
}
if ($OK -gt "0") {
    if ($Debug -eq "2") {
        ""
        "Found $OK file(s) newer than $Days days"
        }
    Add-Content $log "OK"
    if ($Debug -ge "1") {
        Add-Content $log "Found $OK file(s) newer than $Days days"
        }
    }
    else {
        if ($Debug -eq "2") {
        ""
        "Found $OK file(s) newer than $Days days"
        }
    Add-Content $log "Error"
    if ($Debug -ge "1") {
        Add-Content $log "Found $OK file(s) newer than $Days days"
        }
    }
$Host.UI.RawUI.WindowTitle = $titdef

Answer 1

试试：

$Folder1 = 获取子项 $TargetFolder1 -filter *.xml

比使用include（在大量文件上）性能要好得多。甚至更好：

get-childitem $TargetFolder1 -filter *.xml | % {}

---

编辑

我明白了，你的问题是由于include！如果您需要使用通配符和正则表达式来获取子项，请改用filter。由于不使用正则表达式匹配，因此性能更高。

试试：

$Folder1 = 获取子项 $TargetFolder1 -filter *

即使不是很清楚你在那里过滤了什么（或者你想要包含）......一切？可能你根本不需要通配符。

---

以我的拙见，防止内存中的foreach循环的最佳方法是管道。但是，由于脚本的性质（循环内有许多嵌套控件），这并不容易。

尝试：

$文件夹1 | % { # ... }

即使我怀疑它会提高性能。

---

或：

获取子项 $TargetFolder1 -include * | % { # ... }

Answer 2

类似

 $TS=(Get-Date).AddDays(-2)
 $COUNT = (get-childitem -recurse path1,path2 |where-object {$_.LastWriteTime -gt $TS}|measure-object).Count
 if ($COUNT > 0) { Echo "There are $COUNT files" }

可能会更好（我还没有测试过它的性能）