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WIP: Add examples for Start-DebugAttachSession #5246

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WIP: Add examples for Start-DebugAttachSession #5246

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22 changes: 22 additions & 0 deletions examples/ChildDebugSessionAttach.ps1
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Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
# Example on how Start-DebugAttachSession can be used to attach to another
# process. This launches a child process that runs ChildDebugSessionTarget.ps1
# but it can be adapted to attach to any other PowerShell process that is
# either already running or started like this example. To test this example,
# add a breakpoint to ChildDebugSessionTarget.ps1, select the
# 'PowerShell Launch Current File' configuration and press F5.

$pipeName = "TestPipe-$(New-Guid)"
$scriptPath = Join-Path -Path $PSScriptRoot -ChildPath 'ChildDebugSessionTarget.ps1'

$procParams = @{
FilePath = 'pwsh'
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Copilot AI Jul 25, 2025

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Hardcoding 'pwsh' assumes PowerShell Core is available. Consider using $PSVersionTable.PSEdition to detect the current PowerShell edition and use 'powershell' for Windows PowerShell or 'pwsh' for PowerShell Core, or provide a parameter to specify the executable.

Suggested change
$procParams = @{
FilePath = 'pwsh'
$psExecutable = if ($PSVersionTable.PSEdition -eq 'Core') { 'pwsh' } else { 'powershell' }
$procParams = @{
FilePath = $psExecutable

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ArgumentList = ('-CustomPipeName {0} -File "{1}" -WaitForAttach' -f $pipeName, $scriptPath)
PassThru = $true
}
$proc = Start-Process @procParams

Start-DebugAttachSession -CustomPipeName $pipeName -RunspaceId 1

# We need to ensure this debug session stays alive until the process exits. If
# we exit early then the child debug session will also exit.
$proc | Wait-Process
31 changes: 31 additions & 0 deletions examples/ChildDebugSessionTarget.ps1
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[CmdletBinding()]
param (
[Parameter()]
[switch]
$WaitForAttach
)

if ($WaitForAttach) {
# For an attach request we need to wait for the debug pipe runspace to be
# opened before continuing. There is no builtin way to do this so we
# poll the runspace list until a new one is created.
$runspaces = Get-Runspace
while ($true) {
if (Get-Runspace | Where-Object { $_.Id -notin $runspaces.Id }) {
break
}
Start-Sleep -Seconds 1
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Copilot AI Jul 25, 2025

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The polling loop calls Get-Runspace repeatedly without any delay optimization. Consider adding a small delay before each check or implementing exponential backoff to reduce unnecessary CPU usage during the wait period.

Suggested change
while ($true) {
if (Get-Runspace | Where-Object { $_.Id -notin $runspaces.Id }) {
break
}
Start-Sleep -Seconds 1
$currentDelay = 1 # Initial delay duration in seconds
$maxDelay = 16 # Maximum delay duration in seconds
while ($true) {
if (Get-Runspace | Where-Object { $_.Id -notin $runspaces.Id }) {
break
}
Start-Sleep -Seconds $currentDelay
$currentDelay = [math]::Min($currentDelay * 2, $maxDelay) # Exponential backoff

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Copilot AI Jul 25, 2025

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The infinite loop lacks a timeout mechanism. Consider adding a maximum wait time to prevent the script from hanging indefinitely if the debugger never attaches.

Suggested change
$runspaces = Get-Runspace
while ($true) {
if (Get-Runspace | Where-Object { $_.Id -notin $runspaces.Id }) {
break
}
Start-Sleep -Seconds 1
$runspaces = Get-Runspace
$maxWaitTime = 60 # Maximum wait time in seconds
$elapsedTime = 0 # Initialize elapsed time
while ($true) {
if (Get-Runspace | Where-Object { $_.Id -notin $runspaces.Id }) {
break
}
Start-Sleep -Seconds 1
$elapsedTime += 1
if ($elapsedTime -ge $maxWaitTime) {
Write-Host "Timeout reached while waiting for debugger to attach."
break
}

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}

# Windows PowerShell 5.1 will not sync breakpoints until the debugger has
# stopped at least once. We use Wait-Debugger to make this happen.
if ($PSVersionTable.PSVersion -lt '6.0') {
Wait-Debugger
}
else {
Start-Sleep -Seconds 1 # Give the debugger time to sync breakpoints
}
}

$processInfo = "This process is running with PID $PID and has runspace ID $([Runspace]::DefaultRunspace.Id)"
Write-Host $processInfo # Place breakpoint here