Compare Pwsh 7.1 vs 7.0 -Paralell (Reusable Runspaces).ps1

Compare Pwsh 7.1 vs 7.0 -Paralell (Reusable Runspaces).ps1

##Requires -Module BenchPress

Write-Host -fore Yellow 'Example of 7.1''s re-using runspace performance boost'
@'
Future:
    Try -ThrottleLimit

Foreach-Object in 'Pwsh'
- 7.0
    - new parameters '-Paralell', '-AsJob', '-ThrottleLimit'
    - **every** iteration creates a **new** runspace (ie: slower)
- 7.1
    - Runspaces from a runspace pool are reused by default (ie: faster)
    - New parameter: '-UseNewRunspace'
    - To force creating new runspaces like the old behaviour: -UseNewRunspace
    - Pool size default is 5, set using '-ThrottleLimit'

More info:
    (https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/foreach-object?view=powershell-7.2#example-14--using-thread-safe-variable-references)
    (https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_thread_jobs?view=powershell-7.2)
    (https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_jobs?view=powershell-7.2)
'@

$iters = 1000
$iters = 100
Write-Host -for Yellow "Items (Per test) $iters"
Measure-Benchmark -RepeatCount 3 -Detailed -Technique @{
    'New Runspace'                     = {
        # <= 7.0 behaviour
        0..$iters | ForEach-Object -UseNewRunspace -Parallel {
            "Hello $_ "
        }
    }
    'Reuse Runspace'                   = {
        # re-using runspaces in 7.1
        # for the old behaviour, use -UseNewRunspace
        0..$iters | ForEach-Object -Parallel {
            "Hello $_ "
        }
    }
    '-Parallel -AsJob'                 = {
        $Jobs = 0..$iters  | ForEach-Object -AsJob -Parallel {
            "Hello $_"
        }
        $Jobs | Receive-Job -Wait
    }
    '-Parallel -AsJob -UseNewRunspace' = {
        $Jobs = 0..$iters  | ForEach-Object -UseNewRunspace -AsJob -Parallel {
            "Hello $_"
        }
        $Jobs | Receive-Job -Wait
    }
} -GroupName 'Foreach-Object -Parallel' -ov 'BenchResults'
$Summary = $BenchResults | Select-Object -p @(
    'Technique'
    @{name = 'Total Ms'; expression = { $_.Time.TotalMilliseconds } }
    @{name = 'Average Ms'; expression = { $_.Details.AverageTime.TotalMilliseconds } }
) | Sort-Object -Property 'Average Ms'

$Summary | Format-Table

output.txt

Technique                        Time            RelativeSpeed Throughput
---------                        ----            ------------- ----------
-Parallel -AsJob                 00:00:02.107375 1x            1.42/s
Reuse Runspace                   00:00:02.581509 1.22x         1.16/s
New Runspace                     00:00:04.152241 1.97x         0.72/s
-Parallel -AsJob -UseNewRunspace 00:00:04.207801 2x            0.71/s


Technique                         Total Ms Average Ms
---------                         -------- ----------
-Parallel -AsJob                 2107.3756   702.4585
Reuse Runspace                   2581.5093   860.5031
New Runspace                     4152.2411  1384.0803
-Parallel -AsJob -UseNewRunspace 4207.8018  1402.6006