[browser][MT] fix library tests, remove MonoWasmBuildVariant=perftrace

eng/pipelines/extra-platforms/runtime-extra-platforms-wasm.yml

@@ -112,7 +112,7 @@ jobs:
         - browser_wasm
         #- browser_wasm_win
       nameSuffix: _Threading_Smoke
-      extraBuildArgs: /p:MonoWasmBuildVariant=multithread /p:_WasmPThreadPoolSize=8 /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
+      extraBuildArgs: /p:MonoWasmBuildVariant=multithread /p:WasmEnableThreads=true /p:_WasmPThreadPoolSize=8 /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
       shouldRunSmokeOnly: true
       isExtraPlatformsBuild: ${{ parameters.isExtraPlatformsBuild }}
       isWasmOnlyBuild: ${{ parameters.isWasmOnlyBuild }}
@@ -128,7 +128,7 @@ jobs:
         - browser_wasm
         #- browser_wasm_win
       nameSuffix: _Threading
-      extraBuildArgs: /p:MonoWasmBuildVariant=multithread /p:_WasmPThreadPoolSize=8 /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
+      extraBuildArgs: /p:MonoWasmBuildVariant=multithread /p:WasmEnableThreads=true /p:_WasmPThreadPoolSize=8 /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
       isExtraPlatformsBuild: ${{ parameters.isExtraPlatformsBuild }}
       isWasmOnlyBuild: ${{ parameters.isWasmOnlyBuild }}
       # Always run for runtime-wasm because tests are not run in runtime
@@ -137,29 +137,9 @@ jobs:
       # NOTE - Since threading is experimental, we don't want to block mainline work
       shouldContinueOnError: true
       scenarios:
-        - normal
         - WasmTestOnBrowser
-        - WasmTestOnNodeJS
-
-  # Library tests with internal threads only
-  - template: /eng/pipelines/common/templates/wasm-library-tests.yml
-    parameters:
-      platforms:
-        - browser_wasm
-        #- browser_wasm_win
-      nameSuffix: _Threading_PerfTracing
-      extraBuildArgs: /p:MonoWasmBuildVariant=perftrace /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
-      isExtraPlatformsBuild: ${{ parameters.isExtraPlatformsBuild }}
-      isWasmOnlyBuild: ${{ parameters.isWasmOnlyBuild }}
-      # Always run for runtime-wasm because tests are not run in runtime
-      alwaysRun: ${{ parameters.isWasmOnlyBuild }}
+        #- WasmTestOnNodeJS - this is not supported yet, https://github.com/dotnet/runtime/issues/85592
 
-      # NOTE - Since threading is experimental, we don't want to block mainline work
-      shouldContinueOnError: true
-      scenarios:
-        - normal
-        - WasmTestOnBrowser
-        - WasmTestOnNodeJS
 
   # EAT Library tests - only run on linux
   - template: /eng/pipelines/common/templates/wasm-library-aot-tests.yml

eng/pipelines/mono/templates/workloads-build.yml

@@ -55,12 +55,10 @@ jobs:
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.android-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.browser-wasm*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.multithread.browser-wasm*.nupkg
-          IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.perftrace.browser-wasm*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.ios-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.iossimulator-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.maccatalyst-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.multithread.browser-wasm*.nupkg
-          IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.perftrace.browser-wasm*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.tvos-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.tvossimulator-*.nupkg
           IntermediateArtifacts/MonoRuntimePacks/Shipping/Microsoft.NETCore.App.Runtime.Mono.wasi-wasm*.nupkg

eng/pipelines/runtime-official.yml

@@ -180,22 +180,6 @@ extends:
             extraStepsParameters:
               name: MonoRuntimePacks
 
-      - template: /eng/pipelines/common/platform-matrix.yml
-        parameters:
-          jobTemplate: /eng/pipelines/common/global-build-job.yml
-          buildConfig: release
-          runtimeFlavor: mono
-          platforms:
-          - browser_wasm
-          jobParameters:
-            buildArgs: -s mono+libs+host+packs -c $(_BuildConfig) /p:MonoWasmBuildVariant=perftrace /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
-            nameSuffix: AllSubsets_Mono_perftrace
-            isOfficialBuild: ${{ variables.isOfficialBuild }}
-            runtimeVariant: perftrace
-            extraStepsTemplate: /eng/pipelines/common/upload-intermediate-artifacts-step.yml
-            extraStepsParameters:
-              name: MonoRuntimePacks
-
       - template: /eng/pipelines/common/platform-matrix.yml
         parameters:
           jobTemplate: /eng/pipelines/common/global-build-job.yml

eng/pipelines/runtime.yml

@@ -505,14 +505,6 @@ extends:
           scenarios:
             - WasmTestOnBrowser
 
-      - template: /eng/pipelines/common/templates/wasm-build-only.yml
-        parameters:
-          platforms:
-            - browser_wasm
-          nameSuffix: _Threading_PerfTracing
-          extraBuildArgs: /p:MonoWasmBuildVariant=perftrace /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
-          alwaysRun: ${{ variables.isRollingBuild }}
-
       # WASI/WASM
 
       - template: /eng/pipelines/common/templates/wasm-library-tests.yml

eng/testing/tests.browser.targets

@@ -96,6 +96,10 @@
     <_AppArgs Condition="'$(WasmTestAppArgs)' != ''">$(_AppArgs) $(WasmTestAppArgs)</_AppArgs>
 
     <WasmXHarnessMonoArgs Condition="'$(XunitShowProgress)' == 'true'">$(WasmXHarnessMonoArgs) --setenv=XHARNESS_LOG_TEST_START=1</WasmXHarnessMonoArgs>
+    <!-- snapshots are not yet supported with threads -->
+    <WasmXHarnessMonoArgs Condition="'$(MonoWasmBuildVariant)' == 'multithread'">$(WasmXHarnessMonoArgs) --no-memory-snapshot</WasmXHarnessMonoArgs>
+    <!-- help unit test with PlatformDetection.IsThreadingSupported via IsBrowserThreadingSupported env variable -->
+    <WasmXHarnessMonoArgs Condition="'$(MonoWasmBuildVariant)' == 'multithread'">$(WasmXHarnessMonoArgs) --setenv=IsBrowserThreadingSupported=true</WasmXHarnessMonoArgs>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(RunScriptCommand)' == ''">
@@ -104,7 +108,7 @@
 
     <_XHarnessArgs Condition="'$(IsFunctionalTest)' == 'true'"     >$(_XHarnessArgs) --expected-exit-code=$(ExpectedExitCode)</_XHarnessArgs>
     <_XHarnessArgs Condition="'$(WasmXHarnessArgs)' != ''"         >$(_XHarnessArgs) $(WasmXHarnessArgs)</_XHarnessArgs>
-    <_XHarnessArgs Condition="('$(WasmEnableThreads)' == 'true' or '$(WasmEnablePerfTracing)' == 'true') and '$(_XHarnessArs.Contains(&quot;--web-server-use-cop&quot;)' != 'true'">$(_XHarnessArgs) --web-server-use-cop</_XHarnessArgs>
+    <_XHarnessArgs Condition="'$(MonoWasmBuildVariant)' == 'multithread' and '$(_XHarnessArs.Contains(&quot;--web-server-use-cop&quot;)' != 'true'">$(_XHarnessArgs) --web-server-use-cop</_XHarnessArgs>
     <_XHarnessArgs                                                 >$(_XHarnessArgs) -s dotnet.native.js.symbols</_XHarnessArgs>
     <_XHarnessArgs Condition="'$(_UseWasmSymbolicator)' == 'true'" >$(_XHarnessArgs) --symbol-patterns wasm-symbol-patterns.txt</_XHarnessArgs>
     <_XHarnessArgs Condition="'$(_UseWasmSymbolicator)' == 'true'" >$(_XHarnessArgs) --symbolicator WasmSymbolicator.dll,Microsoft.WebAssembly.Internal.SymbolicatorWrapperForXHarness</_XHarnessArgs>
@@ -288,7 +292,6 @@
   <Target Name="_GetRuntimePackNuGetsToBuild" Condition="'$(WasmSkipMissingRuntimePackBuild)' != 'true'" Returns="@(_NuGetsToBuild)">
     <PropertyGroup>
       <_DefaultBuildVariant Condition="'$(MonoWasmBuildVariant)' == 'multithread'">.multithread.</_DefaultBuildVariant>
-      <_DefaultBuildVariant Condition="'$(MonoWasmBuildVariant)' == 'perftrace'">.perftrace.</_DefaultBuildVariant>
       <_DefaultBuildVariant Condition="'$(_DefaultBuildVariant)' == ''">.</_DefaultBuildVariant>
 
       <_DefaultRuntimePackNuGetPath>$(LibrariesShippingPackagesDir)Microsoft.NETCore.App.Runtime.Mono$(_DefaultBuildVariant)$(RuntimeIdentifier).$(PackageVersionForWorkloadManifests).nupkg</_DefaultRuntimePackNuGetPath>
@@ -305,7 +308,6 @@
 
     <ItemGroup>
       <_BuildVariants Include="multithread" Condition="'$(_DefaultBuildVariant)' != '.multithread.'" />
-      <_BuildVariants Include="perftrace"   Condition="'$(_DefaultBuildVariant)' != '.perftrace.'" />
 
       <_NuGetsToBuild Include="$(LibrariesShippingPackagesDir)Microsoft.NETCore.App.Runtime.Mono.%(_BuildVariants.Identity).$(RuntimeIdentifier).$(PackageVersionForWorkloadManifests).nupkg"
                       Project="$(InstallerProjectRoot)pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.sfxproj"

src/libraries/Common/tests/TestUtilities/System/PlatformDetection.cs

@@ -116,7 +116,7 @@ public static bool IsPrivilegedProcess
         public static bool FileCreateCaseSensitive => IsCaseSensitiveOS;
 #endif
 
-        public static bool IsThreadingSupported => !IsBrowser && !IsWasi;
+        public static bool IsThreadingSupported => !IsWasi && IsEnvironmentVariableTrue("IsBrowserThreadingSupported");
         public static bool IsBinaryFormatterSupported => IsNotMobile && !IsNativeAot;
 
         public static bool IsStartingProcessesSupported => !IsiOS && !IstvOS;

src/libraries/System.Diagnostics.Tracing/src/System.Diagnostics.Tracing.csproj

@@ -4,8 +4,7 @@
     <IsPartialFacadeAssembly>true</IsPartialFacadeAssembly>
   </PropertyGroup>
 
-  <PropertyGroup Condition="'$(MonoWasmBuildVariant)' == 'multithread' or
-                            '$(MonoWasmBuildVariant)' == 'perftrace'">
+  <PropertyGroup Condition="'$(MonoWasmBuildVariant)' == 'multithread'">
     <!-- when wasm threading is enabled the implementation in CoreLib won't have the UnsupportedOSAttribute for browser,
          but this contract still does since we only expose the wasm threading through System.Diagnostics.Tracing.WebAssembly.PerfTracing
          so we need to baseline the ApiCompat errors related to that -->

src/libraries/System.Private.CoreLib/ref/System.Private.CoreLib.csproj

@@ -10,7 +10,7 @@
     <NoWarn>$(NoWarn);0809;0618;CS8614;CS3015</NoWarn>
     <StrongNameKeyId>SilverlightPlatform</StrongNameKeyId>
     <DisableImplicitFrameworkReferences>true</DisableImplicitFrameworkReferences>
-    <FeatureWasmPerfTracing Condition="'$(MonoWasmBuildVariant)' == 'multithread' or '$(MonoWasmBuildVariant)' == 'perftrace'">true</FeatureWasmPerfTracing>
+    <FeatureWasmPerfTracing Condition="'$(MonoWasmBuildVariant)' == 'multithread'">true</FeatureWasmPerfTracing>
     <FeatureWasmThreads Condition="'$(MonoWasmBuildVariant)' == 'multithread'">true</FeatureWasmThreads>
     <DefineConstants Condition="'$(FeatureWasmPerfTracing)' == 'true'">$(DefineConstants);FEATURE_WASM_PERFTRACING</DefineConstants>
     <DefineConstants Condition="'$(FeatureWasmThreads)' == 'true'">$(DefineConstants);FEATURE_WASM_THREADS</DefineConstants>

src/libraries/System.Threading.Thread/ref/System.Threading.Thread.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>$(NetCoreAppCurrent)</TargetFramework>
+    <FeatureWasmThreads Condition="'$(TargetPlatformIdentifier)' == 'browser' and '$(MonoWasmBuildVariant)' == 'multithread'">true</FeatureWasmThreads>
     <DefineConstants Condition="'$(FeatureWasmThreads)' == 'true'">$(DefineConstants);FEATURE_WASM_THREADS</DefineConstants>
   </PropertyGroup>
 

src/libraries/tests.proj

@@ -52,10 +52,6 @@
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(MonoWasmBuildVariant)' != 'multithread'" >
     <ProjectExclusions Include="$(MonoProjectRoot)sample\wasm\browser-threads\Wasm.Browser.Threads.Sample.csproj" />
     <ProjectExclusions Include="$(MonoProjectRoot)sample\wasm\browser-threads-minimal\Wasm.Browser.Threads.Minimal.Sample.csproj" />
-  </ItemGroup>
-
-  <!-- Samples that require a perf-tracing wasm runtime -->
-  <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(MonoWasmBuildVariant)' != 'perftrace'" >
     <ProjectExclusions Include="$(MonoProjectRoot)sample\wasm\browser-eventpipe\Wasm.Browser.EventPipe.Sample.csproj" />
   </ItemGroup>
 
@@ -375,13 +371,6 @@
     <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.WebSockets.Client\tests\System.Net.WebSockets.Client.Tests.csproj" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(MonoWasmBuildVariant)' == 'perftrace' and '$(RunDisabledWasmTests)' != 'true'">
-    <!-- Issue: https://github.com/dotnet/runtime/issues/74411 -->
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.Http\tests\FunctionalTests\System.Net.Http.Functional.Tests.csproj" />
-    <!-- Issue: https://github.com/dotnet/runtime/issues/74413 -->
-    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Net.WebSockets.Client\tests\System.Net.WebSockets.Client.Tests.csproj" />
-  </ItemGroup>
-
   <!-- Aggressive Trimming related failures -->
   <ItemGroup Condition="('$(TargetOS)' != 'browser' and '$(RunAOTCompilation)' == 'true' and '$(MonoForceInterpreter)' != 'true') or ('$(TargetOS)' == 'browser' and '$(BuildAOTTestsOnHelix)' == 'true' and '$(RunDisabledWasmTests)' != 'true')">
   </ItemGroup>

src/mono/System.Private.CoreLib/System.Private.CoreLib.csproj

@@ -121,7 +121,7 @@
 
     <FeatureMono>true</FeatureMono>
     <FeatureWasmThreads Condition="('$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true') and '$(MonoWasmBuildVariant)' == 'multithread'">true</FeatureWasmThreads>
-    <FeatureWasmPerfTracing Condition="('$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true') and ('$(MonoWasmBuildVariant)' == 'multithread' or '$(MonoWasmBuildVariant)' == 'perftrace')">true</FeatureWasmPerfTracing>
+    <FeatureWasmPerfTracing Condition="('$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true') and ('$(MonoWasmBuildVariant)' == 'multithread')">true</FeatureWasmPerfTracing>
     <FeatureManagedEtwChannels>true</FeatureManagedEtwChannels>
     <FeatureManagedEtw>true</FeatureManagedEtw>
     <FeaturePortableTimer Condition="'$(TargetsBrowser)' != 'true' and '$(TargetsWasi)' != 'true'">true</FeaturePortableTimer>

src/mono/cmake/config.h.in

@@ -299,9 +299,6 @@
 /* Disable Threads */
 #cmakedefine DISABLE_THREADS 1
 
-/* Disable user thread creation on WebAssembly */
-#cmakedefine DISABLE_WASM_USER_THREADS 1
-
 /* Disable MONO_LOG_DEST */
 #cmakedefine DISABLE_LOG_DEST
 

src/mono/cmake/options.cmake

@@ -56,7 +56,6 @@ option (ENABLE_OVERRIDABLE_ALLOCATORS "Enable overridable allocator support")
 option (ENABLE_SIGALTSTACK "Enable support for using sigaltstack for SIGSEGV and stack overflow handling, this doesn't work on some platforms")
 option (USE_MALLOC_FOR_MEMPOOLS "Use malloc for each single mempool allocation, so tools like Valgrind can run better")
 option (STATIC_COMPONENTS "Compile mono runtime components as static (not dynamic) libraries")
-option (DISABLE_WASM_USER_THREADS "Disable creation of user managed threads on WebAssembly, only allow runtime internal managed and native threads")
 option (ENABLE_WEBCIL "Enable the WebCIL loader")
 
 set (MONO_GC "sgen" CACHE STRING "Garbage collector implementation (sgen or boehm). Default: sgen")

src/mono/mono.proj

@@ -9,7 +9,6 @@
       - MonoVerboseBuild - enable verbose build
       - MonoThreadSuspend - coop,hybrid,preemptive - default thread suspend mode
       - MonoWasmThreads - build runtime with threading support for wasm
-      - MonoWasmThreadsNoUser - build runtime with threading support for wasm, but with only internal utility threads (MonoWasmThreads must be defined too)
   -->
 
   <PropertyGroup>
@@ -54,8 +53,7 @@
     <RepositoryEngineeringCommonDir>$([MSBuild]::NormalizeDirectory('$(RepositoryEngineeringDir)', 'common'))</RepositoryEngineeringCommonDir>
     <CrossToolchainFile>$([MSBuild]::NormalizePath('$(RepositoryEngineeringCommonDir)', 'cross', 'toolchain.cmake'))</CrossToolchainFile>
     <MonoWasmThreads Condition="'$(MonoWasmBuildVariant)' == 'singlethread'">false</MonoWasmThreads>
-    <MonoWasmThreads Condition="'$(MonoWasmBuildVariant)' == 'multithread' or '$(MonoWasmBuildVariant)' == 'perftrace'">true</MonoWasmThreads>
-    <MonoWasmThreadsNoUser Condition="'$(MonoWasmBuildVariant)' == 'perftrace'">true</MonoWasmThreadsNoUser>
+    <MonoWasmThreads Condition="'$(MonoWasmBuildVariant)' == 'multithread'">true</MonoWasmThreads>
     <MonoEnableAssertMessages Condition="'$(MonoEnableAssertMessages)' == '' and '$(TargetsWasi)' == 'true'">true</MonoEnableAssertMessages>
   </PropertyGroup>
 
@@ -417,7 +415,6 @@
       <_MonoMinimal Condition="'$(Configuration)' == 'Release'">,debugger_agent,log_dest</_MonoMinimal>
       <_MonoMinimal Condition="'$(Configuration)' == 'Release' and '$(MonoEnableAssertMessages)' != 'true'">$(_MonoMinimal),assert_messages</_MonoMinimal>
       <_MonoMinimal Condition="'$(MonoWasmThreads)' != 'true'">$(_MonoMinimal),threads</_MonoMinimal>
-      <_MonoMinimal Condition="'$(MonoWasmThreadsNoUser)' == 'true'">$(_MonoMinimal),wasm_user_threads</_MonoMinimal>
     </PropertyGroup>
     <ItemGroup Condition="'$(TargetsBrowser)' == 'true' or '$(TargetsWasi)' == 'true'">
       <_MonoCMakeArgs Include="-DENABLE_MINIMAL=jit,sgen_major_marksweep_conc,sgen_split_nursery,sgen_gc_bridge,sgen_toggleref,sgen_debug_helpers,sgen_binary_protocol,logging,interpreter,qcalls$(_MonoMinimal)"/>

src/mono/mono/mini/mini-wasm.c

@@ -586,7 +586,11 @@ mono_thread_state_init_from_handle (MonoThreadUnwindState *tctx, MonoThreadInfo
 EMSCRIPTEN_KEEPALIVE void
 mono_wasm_execute_timer (void)
 {
-	g_assert (timer_handler);
+	// callback could be null if timer was never used by the application, but only by prevent_timer_throttling_tick()
+	if (timer_handler==NULL) {
+		return;
+	}
+
 	background_job_cb cb = timer_handler;
 	cb ();
 }

src/mono/nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/WorkloadManifest.json.in

@@ -19,7 +19,6 @@
       "packs": [
         "Microsoft.NET.Runtime.WebAssembly.Templates",
         "Microsoft.NETCore.App.Runtime.Mono.multithread.browser-wasm",
-        "Microsoft.NETCore.App.Runtime.Mono.perftrace.browser-wasm"
       ],
       "extends": [ "wasm-tools" ],
       "platforms": [ "win-x64", "win-arm64", "linux-x64", "osx-x64", "osx-arm64" ]
@@ -376,10 +375,6 @@
       "kind": "framework",
       "version": "${PackageVersion}"
     },
-    "Microsoft.NETCore.App.Runtime.Mono.perftrace.browser-wasm" : {
-      "kind": "framework",
-      "version": "${PackageVersion}"
-    },
     "Microsoft.NETCore.App.Runtime.Mono.wasi-wasm" : {
       "kind": "framework",
       "version": "${PackageVersion}"

src/mono/nuget/Microsoft.NET.Workload.Mono.Toolchain.Current.Manifest/WorkloadManifest.targets.in

@@ -149,7 +149,6 @@
       <LatestRuntimeFrameworkVersion Condition="'%(KnownRuntimePack.TargetFramework)' == '${NetCoreAppCurrent}' and '%(KnownRuntimePack.RuntimePackLabels)' == 'Mono'">$(_MonoWorkloadRuntimePackPackageVersion)</LatestRuntimeFrameworkVersion>
       <!-- Overrides for wasm threading support -->
       <RuntimePackNamePatterns Condition="'$(RuntimeIdentifier)' == 'browser-wasm' and '$(WasmEnableThreads)' == 'true'">Microsoft.NETCore.App.Runtime.Mono.multithread.**RID**</RuntimePackNamePatterns>
-      <RuntimePackNamePatterns Condition="'$(RuntimeIdentifier)' == 'browser-wasm' and '$(WasmEnablePerfTracing)' == 'true'">Microsoft.NETCore.App.Runtime.Mono.perftrace.**RID**</RuntimePackNamePatterns>
     </KnownRuntimePack>
     <KnownWebAssemblySdkPack Update="@(KnownWebAssemblySdkPack)">
       <WebAssemblySdkPackVersion Condition="'%(KnownWebAssemblySdkPack.TargetFramework)' == '${NetCoreAppCurrent}'">$(_KnownWebAssemblySdkPackVersion)</WebAssemblySdkPackVersion>

src/mono/sample/wasm/DefaultBrowserSample.targets

@@ -6,6 +6,7 @@
     <!-- note that enabling debugger disables interp optimizations -->
     <WasmDebugLevel Condition="'$(Configuration)' == 'Debug'">-1</WasmDebugLevel>
     <GenerateRunScriptForSample Condition="'$(ArchiveTests)' == 'true'">true</GenerateRunScriptForSample>
+    <WasmXHarnessArgs Condition="'$(WasmEnableThreads)' == 'true'">$(WasmXHarnessArgs) --web-server-use-cop</WasmXHarnessArgs>
     <RunScriptCommand>$(ExecXHarnessCmd) wasm test-browser  --app=. --browser=Chrome $(XHarnessBrowserPathArg) $(WasmXHarnessArgs) --html-file=index.html --output-directory=$(XHarnessOutput) -- $(MSBuildProjectName).dll</RunScriptCommand>
   </PropertyGroup>
 

src/mono/sample/wasm/Directory.Build.props

@@ -15,7 +15,6 @@
   <PropertyGroup>
     <OutputPath>bin</OutputPath>
     <WasmAppDir>$(MSBuildProjectDirectory)\bin\$(Configuration)\AppBundle\</WasmAppDir>
-    <WasmXHarnessArgs Condition="'$(WasmEnableThreads)' == 'true' or '$(WasmEnablePerfTracing)' == 'true' or '$(MonoWasmBuildVariant)' == 'multithread' or '$(MonoWasmBuildVariant)' == 'perftrace'">$(WasmXHarnessArgs) --web-server-use-cop</WasmXHarnessArgs>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
     <WasmNativeStrip>false</WasmNativeStrip>