PowerShell 中使用json对象的性能比较

*****Warning. This is from a preview release******

PowerShell v2 brought the ability to create a custom object via the following method:

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$CustomObject1 = New-Object psobject -Property @{a=1; b=2; c=3; d=4}

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$CustomObject1 | Format-List

PowerShell v3 brings the possibility to create a custom object via

[pscustomobject]

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$CustomObject2 = [pscustomobject]@{a=1; b=2; c=3; d=4}

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$CustomObject2 | Format-List

Note: both methods create a PSCustomObject with NoteProperties, not a hashtable object

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$CustomObject1 | Get-Member

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$CustomObject2 | Get-Member

So, why would you want to do it this way? Well firstly it preserves the insertion order,which helps with my OCD issues again. However, the main reason I have seen so far is that it is also a lot quicker. Fellow PowerShell MVP Tome Tanasovski carried out some basic performance testing which I thought I would highlight here.

There are four different ways you can create a custom object and a typical use case would be using PowerShell for reporting purposes, e.g. iterating through a list of VMs and pulling out various properties of them to create a report. With a very basic example, let’s have a look at the speed differences:

1) Select-Object

Not everybody knows that it’s possible to create a custom object with Select-Object. This was a handy trick since v1 days and was pretty quick too.

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$TestSelect = {

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(0..5000) | ForEach-Object {$CustomObject = "" | Select-Object Name,ID

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$CustomObject.Name = "Test Name"

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$CustomObject.ID = $_

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$CustomObject

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}

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}

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Measure-Command $TestSelect | Format-Table TotalSeconds -Autosize

2) Add-Member

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$TestAddMember = {

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(0..5000) | ForEach-Object {$CustomObject = New-Objectpsobject

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$CustomObject | Add-Member -Name "Name" -Value "Test Name"

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$CustomObject | Add-Member -Name "ID" -Value $_

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$CustomObject

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}

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}

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Measure-Command $TestAddMember | Format-Table TotalSeconds -Autosize

3) Property Parameter

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$TestProperty = {

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(0..5000) | ForEach-Object {New-Object psobject -Property@{Name = "Test Name"; ID = $_}}

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}

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Measure-Command $TestProperty | Format-Table TotalSeconds -Autosize

4) [pscustomobject]

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$TestProperty = {

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(0..5000) | ForEach-Object {[pscustomobject]@{Name = "Test Name"; ID = $_}}

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}

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Measure-Command $TestPSCustomObject | Format-TableTotalSeconds -Autosize

So a summary of the these basic testing results looks pretty good for [pscustomobject]!

Select-Object = 7.74s

Add-Member = 28.87s

Property = 7.29

[pscustomobject] = 0.94s

I hope to try out [pscustomobject] on some of my reporting scripts and see what difference it makes to real world testing.

PowerShell 中使用json对象的性能比较

PowerShell v3 – Creating Objects With [pscustomobject] – it’s fast!