Update VM Scale Set to VS 2019 Preview 3 (#1015)

* Update the Azure VM Scale Set that runs the CI pipeline to VS 2019 Preview 3
* Install the `psutil` python module while provisioning VMs (Fixes #773)

Co-authored-by: Curtis Jacques Bezault <curtbezault@gmail.com>

README.md

@@ -140,7 +140,7 @@ Just try to follow these rules, so we can spend more time fixing bugs and implem
 The STL uses boost-math headers to provide P0226R1 Mathematical Special Functions. We recommend using [vcpkg][] to
 acquire this dependency.
 
-1. Install Visual Studio 2019 16.7 Preview 2 or later.
+1. Install Visual Studio 2019 16.7 Preview 3 or later.
 2. Invoke `git clone https://github.com/microsoft/vcpkg`
 3. Invoke `cd vcpkg`
 4. Invoke `.\bootstrap-vcpkg.bat`
@@ -159,7 +159,7 @@ acquire this dependency.
 These instructions assume you're targeting `x64-windows`; you can change this constant below to target other
 architectures.
 
-1. Install [CMake][] 3.16.5 or later, [Ninja][] 1.10.0 or later, and Visual Studio 2019 16.7 Preview 2 or later.
+1. Install [CMake][] 3.16.5 or later, [Ninja][] 1.10.0 or later, and Visual Studio 2019 16.7 Preview 3 or later.
 2. Invoke `git clone https://github.com/microsoft/vcpkg`
 3. Invoke `cd vcpkg`
 4. Invoke `.\bootstrap-vcpkg.bat`

azure-devops/provision-image.ps1

@@ -353,6 +353,30 @@ Function InstallCuda {
   }
 }
 
+<#
+.SYNOPSIS
+Install or upgrade a pip package.
+
+.DESCRIPTION
+Installs or upgrades a pip package specified in $Package.
+
+.PARAMETER Package
+The name of the package to be installed or upgraded.
+#>
+Function PipInstall {
+  Param(
+    [String]$Package
+  )
+
+  try {
+    Write-Host 'Installing or upgrading $Package...'
+    python.exe -m pip install --upgrade $Package
+    Write-Host 'Done installing or upgrading $Package'
+  }
+  catch {
+    Write-Error "Failed to install or upgrade $Package"
+  }
+}
 
 Write-Host "AdminUser password not supplied; assuming already running as AdminUser"
 
@@ -371,8 +395,13 @@ InstallLLVM $LlvmUrl
 InstallPython $PythonUrl
 InstallVisualStudio -Workloads $Workloads -BootstrapperUrl $VisualStudioBootstrapperUrl
 InstallCuda -Url $CudaUrl -Features $CudaFeatures
+
 Write-Host 'Updating PATH...'
 $environmentKey = Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' -Name Path
+$Env:PATH="$($environmentKey.Path);C:\Program Files\CMake\bin;C:\Program Files\LLVM\bin"
 Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Session Manager\Environment' `
   -Name Path `
-  -Value "$($environmentKey.Path);C:\Program Files\CMake\bin;C:\Program Files\LLVM\bin"
+  -Value "$Env:PATH"
+
+PipInstall pip
+PipInstall psutil

azure-devops/run-build.yml

@@ -12,10 +12,6 @@ jobs:
     litFlags: '-j$(testParallelism);--timeout=240;--shuffle;--xunit-xml-output=$(buildOutputLocation)/test-results.xml'
     vcpkgLocation: '$(Build.SourcesDirectory)/vcpkg'
   steps:
-    - script: |
-        python -m pip install --upgrade pip
-        pip install psutil
-      displayName: pip install psutil
     - script: |
         if exist "$(tmpDir)" (
           rmdir /S /Q $(tmpDir)

azure-pipelines.yml

@@ -4,7 +4,7 @@
 # Build STL targeting x86, x64, arm, arm64
 
 variables:
-  agentPool: 'StlBuild-2020-06-18'
+  agentPool: 'StlBuild-2020-07-08-2'
   tmpDir: 'D:\Temp'
 
 stages: