Opt Into Perf Logging (#6274)

eng/cibuild_bootstrapped_msbuild.ps1

@@ -53,6 +53,7 @@ $RepoRoot = [System.IO.Path]::GetFullPath($RepoRoot).TrimEnd($([System.IO.Path]:
 $ArtifactsDir = Join-Path $RepoRoot "artifacts"
 $Stage1Dir = Join-Path $RepoRoot "stage1"
 $Stage1BinDir = Join-Path $Stage1Dir "bin"
+$PerfLogDir = Join-Path $ArtifactsDir "log\$Configuration\PerformanceLogs"
 
 if ($msbuildEngine -eq '')
 {
@@ -123,6 +124,9 @@ try {
   # Ensure that debug bits fail fast, rather than hanging waiting for a debugger attach.
   $env:MSBUILDDONOTLAUNCHDEBUGGER="true"
 
+  # Opt into performance logging. https://github.com/dotnet/msbuild/issues/5900
+  $env:DOTNET_PERFLOG_DIR=$PerfLogDir
+
   # When using bootstrapped MSBuild:
   # - Turn off node reuse (so that bootstrapped MSBuild processes don't stay running and lock files)
   # - Do run tests

eng/cibuild_bootstrapped_msbuild.sh

@@ -39,6 +39,7 @@ done
 RepoRoot="$ScriptRoot/.."
 ArtifactsDir="$RepoRoot/artifacts"
 Stage1Dir="$RepoRoot/stage1"
+PerfLogDir="$ArtifactsDir/log/$configuration/PerformanceLogs"
 
 . "$ScriptRoot/common/tools.sh"
 InitializeDotNetCli true
@@ -86,6 +87,9 @@ mv $ArtifactsDir $Stage1Dir
 # Ensure that debug bits fail fast, rather than hanging waiting for a debugger attach.
 export MSBUILDDONOTLAUNCHDEBUGGER=true
 
+# Opt into performance logging.
+export DOTNET_PERFLOG_DIR=$PerfLogDir
+
 # Prior to 3.0, the Csc task uses this environment variable to decide whether to run
 # a CLI host or directly execute the compiler.
 export DOTNET_HOST_PATH="$_InitializeDotNetCli/dotnet"

src/MSBuild.UnitTests/PerfLog_Tests.cs

@@ -74,7 +74,7 @@ public void TestPerfLogEnabledProducedLogFile()
         }
 
         [Fact]
-        public void TestPerfLogDirectoryDoesNotExist()
+        public void TestPerfLogDirectoryGetsCreated()
         {
             using (TestEnvironment testEnv = TestEnvironment.Create(_output))
             {
@@ -101,7 +101,7 @@ public void TestPerfLogDirectoryDoesNotExist()
                 RunnerUtilities.ExecMSBuild(msbuildParameters, out bool successfulExit);
                 successfulExit.ShouldBeTrue();
 
-                Directory.Exists(perfLogPath).ShouldBeFalse();
+                Directory.Exists(perfLogPath).ShouldBeTrue();
             }
         }
     }

src/MSBuild/PerformanceLogEventListener.cs

@@ -7,6 +7,7 @@
 using System.IO;
 using System.Text;
 using Microsoft.Build.Eventing;
+using Microsoft.Build.Shared;
 
 namespace Microsoft.Build.CommandLine
 {
@@ -51,7 +52,8 @@ internal static PerformanceLogEventListener Create()
 
                 // Check to see if we should enable the event listener.
                 string logDirectory = Environment.GetEnvironmentVariable(PerfLogDirEnvVar);
-                if (Directory.Exists(logDirectory))
+
+                if (!string.IsNullOrEmpty(logDirectory) && Directory.CreateDirectory(logDirectory).Exists)
                 {
                     eventListener = new PerformanceLogEventListener();
                     eventListener.Initialize(logDirectory);

src/Shared/UnitTests/TestAssemblyInfo.cs

@@ -40,6 +40,10 @@ public MSBuildTestAssemblyFixture()
         //  (VerifySubToolsetVersionSetByConstructorOverridable), as the environment variable would take precedence.
         _testEnvironment.SetEnvironmentVariable("VisualStudioVersion", string.Empty);
 
+        // Prevent test assemblies from logging any performance info.
+        // https://github.com/dotnet/msbuild/pull/6274
+        _testEnvironment.SetEnvironmentVariable("DOTNET_PERFLOG_DIR", string.Empty);
+
         SetDotnetHostPath(_testEnvironment);
 
         //  Use a project-specific temporary path