ci: measure Windows Bazel test bottlenecks

.github/scripts/measure-windows-bazel.ps1

@@ -0,0 +1,200 @@
+<#
+Collect lightweight host telemetry around Windows Bazel CI runs.
+
+The monitor mode intentionally uses built-in Windows performance counters so
+the workflow does not need to install a profiler on the runner. The summarize
+mode keeps the useful aggregate in the job log while the raw CSV remains
+available as an artifact for deeper analysis.
+#>
+
+[CmdletBinding()]
+param(
+  [Parameter(Mandatory = $true)]
+  [ValidateSet('monitor', 'summarize')]
+  [string]$Mode,
+
+  [Parameter(Mandatory = $true)]
+  [string]$OutputPath,
+
+  [string]$StopFile,
+
+  [ValidateRange(1, 60)]
+  [int]$IntervalSeconds = 15
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+
+function Get-SingleCounterValue {
+  param(
+    [Parameter(Mandatory = $true)]
+    [object]$CounterSample,
+
+    [Parameter(Mandatory = $true)]
+    [string]$PathPattern
+  )
+
+  $sample = $CounterSample.CounterSamples |
+    Where-Object { $_.Path -like $PathPattern } |
+    Select-Object -First 1
+  if ($null -eq $sample) {
+    return 0
+  }
+  return [double]$sample.CookedValue
+}
+
+function Get-SummedCounterValue {
+  param(
+    [Parameter(Mandatory = $true)]
+    [object]$CounterSample,
+
+    [Parameter(Mandatory = $true)]
+    [string]$PathPattern
+  )
+
+  $samples = $CounterSample.CounterSamples |
+    Where-Object { $_.Path -like $PathPattern }
+  if ($null -eq $samples) {
+    return 0
+  }
+  return [double](($samples | Measure-Object -Property CookedValue -Sum).Sum)
+}
+
+function Get-Percentile {
+  param(
+    [Parameter(Mandatory = $true)]
+    [double[]]$Values,
+
+    [Parameter(Mandatory = $true)]
+    [ValidateRange(0, 100)]
+    [int]$Percentile
+  )
+
+  if ($Values.Count -eq 0) {
+    return 0
+  }
+  $sorted = $Values | Sort-Object
+  $index = [math]::Ceiling(($Percentile / 100) * $sorted.Count) - 1
+  return [double]$sorted[[math]::Max(0, $index)]
+}
+
+function Get-NumericColumn {
+  param(
+    [Parameter(Mandatory = $true)]
+    [object[]]$Rows,
+
+    [Parameter(Mandatory = $true)]
+    [string]$Name
+  )
+
+  return [double[]]@($Rows | ForEach-Object { [double]$_.$Name })
+}
+
+function Format-BytesPerSecond {
+  param([double]$Value)
+
+  return '{0:N1} MiB/s' -f ($Value / 1MB)
+}
+
+function Write-Summary {
+  if (-not (Test-Path -LiteralPath $OutputPath)) {
+    Write-Output "No Windows Bazel telemetry file found at $OutputPath."
+    return
+  }
+
+  $rows = @(Import-Csv -LiteralPath $OutputPath)
+  if ($rows.Count -eq 0) {
+    Write-Output "Windows Bazel telemetry file at $OutputPath had no samples."
+    return
+  }
+
+  $cpu = Get-NumericColumn -Rows $rows -Name cpu_percent
+  $processorQueue = Get-NumericColumn -Rows $rows -Name processor_queue_length
+  $diskRead = Get-NumericColumn -Rows $rows -Name disk_read_bytes_per_sec
+  $diskWrite = Get-NumericColumn -Rows $rows -Name disk_write_bytes_per_sec
+  $diskLatency = Get-NumericColumn -Rows $rows -Name disk_seconds_per_transfer
+  $diskQueue = Get-NumericColumn -Rows $rows -Name disk_queue_length
+  $networkReceived = Get-NumericColumn -Rows $rows -Name network_received_bytes_per_sec
+  $networkSent = Get-NumericColumn -Rows $rows -Name network_sent_bytes_per_sec
+  $memory = Get-NumericColumn -Rows $rows -Name available_memory_mib
+
+  $sampledSeconds = $rows.Count * $IntervalSeconds
+  $networkBytes = (($networkReceived | Measure-Object -Average).Average + ($networkSent | Measure-Object -Average).Average) * $sampledSeconds
+  $diskBytes = (($diskRead | Measure-Object -Average).Average + ($diskWrite | Measure-Object -Average).Average) * $sampledSeconds
+
+  Write-Output 'Windows Bazel host telemetry summary:'
+  Write-Output ('  samples: {0} (~{1:N0}s)' -f $rows.Count, $sampledSeconds)
+  Write-Output ('  cpu: avg {0:N1}%, p95 {1:N1}%, max {2:N1}%; processor queue max {3:N1}' -f
+    ($cpu | Measure-Object -Average).Average,
+    (Get-Percentile -Values $cpu -Percentile 95),
+    ($cpu | Measure-Object -Maximum).Maximum,
+    ($processorQueue | Measure-Object -Maximum).Maximum)
+  Write-Output ('  disk: read avg {0}, write avg {1}, p95 latency {2:N1}ms, queue max {3:N1}, sampled total {4:N2} GiB' -f
+    (Format-BytesPerSecond (($diskRead | Measure-Object -Average).Average)),
+    (Format-BytesPerSecond (($diskWrite | Measure-Object -Average).Average)),
+    ((Get-Percentile -Values $diskLatency -Percentile 95) * 1000),
+    ($diskQueue | Measure-Object -Maximum).Maximum,
+    ($diskBytes / 1GB))
+  Write-Output ('  network: receive avg {0}, send avg {1}, sampled total {2:N2} GiB' -f
+    (Format-BytesPerSecond (($networkReceived | Measure-Object -Average).Average)),
+    (Format-BytesPerSecond (($networkSent | Measure-Object -Average).Average)),
+    ($networkBytes / 1GB))
+  Write-Output ('  memory: minimum {0:N0} MiB available' -f ($memory | Measure-Object -Minimum).Minimum)
+}
+
+if ($Mode -eq 'summarize') {
+  Write-Summary
+  exit 0
+}
+
+if ([string]::IsNullOrWhiteSpace($StopFile)) {
+  throw 'monitor mode requires -StopFile.'
+}
+
+$outputDirectory = Split-Path -Parent $OutputPath
+if (-not [string]::IsNullOrWhiteSpace($outputDirectory)) {
+  New-Item -ItemType Directory -Path $outputDirectory -Force | Out-Null
+}
+
+$counterPaths = @(
+  '\Processor(_Total)\% Processor Time',
+  '\System\Processor Queue Length',
+  '\PhysicalDisk(_Total)\Disk Read Bytes/sec',
+  '\PhysicalDisk(_Total)\Disk Write Bytes/sec',
+  '\PhysicalDisk(_Total)\Avg. Disk sec/Transfer',
+  '\PhysicalDisk(_Total)\Avg. Disk Queue Length',
+  '\Network Interface(*)\Bytes Received/sec',
+  '\Network Interface(*)\Bytes Sent/sec',
+  '\Memory\Available MBytes'
+)
+
+while (-not (Test-Path -LiteralPath $StopFile)) {
+  try {
+    $sample = Get-Counter -Counter $counterPaths -ErrorAction Stop
+    $row = [pscustomobject]@{
+      timestamp = (Get-Date).ToUniversalTime().ToString('o')
+      cpu_percent = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\processor(_total)\% processor time'
+      processor_queue_length = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\system\processor queue length'
+      disk_read_bytes_per_sec = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\physicaldisk(_total)\disk read bytes/sec'
+      disk_write_bytes_per_sec = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\physicaldisk(_total)\disk write bytes/sec'
+      disk_seconds_per_transfer = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\physicaldisk(_total)\avg. disk sec/transfer'
+      disk_queue_length = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\physicaldisk(_total)\avg. disk queue length'
+      network_received_bytes_per_sec = Get-SummedCounterValue -CounterSample $sample -PathPattern '*\network interface(*)\bytes received/sec'
+      network_sent_bytes_per_sec = Get-SummedCounterValue -CounterSample $sample -PathPattern '*\network interface(*)\bytes sent/sec'
+      available_memory_mib = Get-SingleCounterValue -CounterSample $sample -PathPattern '*\memory\available mbytes'
+    }
+    $row | Export-Csv -LiteralPath $OutputPath -Append -NoTypeInformation
+  }
+  catch {
+    Write-Warning "Windows Bazel telemetry sample failed: $($_.Exception.Message)"
+  }
+
+  # Check the stop file once a second so the monitor does not add up to one
+  # full sampling interval to the measured workflow step during cleanup.
+  for ($second = 0; $second -lt $IntervalSeconds; $second += 1) {
+    if (Test-Path -LiteralPath $StopFile) {
+      break
+    }
+    Start-Sleep -Seconds 1
+  }
+}