Cache: immediate eviction in net4 tests (#18889)

Author: majocha

azure-pipelines-PR.yml

@@ -321,6 +321,7 @@ stages:
 
           - script: eng\CIBuildNoPublish.cmd -compressallmetadata -buildnorealsig -testDesktop -configuration Release -testBatch $(System.JobPositionInPhase)
             env:
+              FSharp_CacheEvictionImmediate: true
               DOTNET_DbgEnableMiniDump: 1
               DOTNET_DbgMiniDumpType: 3 # Triage dump, 1 for mini, 2 for Heap, 3 for triage, 4 for full. Don't use 4 unless you know what you're doing.
               DOTNET_DbgMiniDumpName: $(Build.SourcesDirectory)\artifacts\log\Release\$(Build.BuildId)-%e-%p-%t.dmp
@@ -456,11 +457,13 @@ stages:
               fsharpqa_release:
                 _configuration: Release
                 _testKind: testFSharpQA
+                FSharp_CacheEvictionImmediate: true
                 transparentCompiler:
               vs_release:
                 _configuration: Release
                 _testKind: testVs
                 setupVsHive: true
+                FSharp_CacheEvictionImmediate: true
                 transparentCompiler:
               transparent_compiler_release:
                 _configuration: Release
@@ -559,6 +562,7 @@ stages:
 
           - script: eng\CIBuildNoPublish.cmd -compressallmetadata -configuration Release -testDesktop -testBatch $(System.JobPositionInPhase)
             env:
+              FSharp_CacheEvictionImmediate: true
               DOTNET_DbgEnableMiniDump: 1
               DOTNET_DbgMiniDumpType: 3 # Triage dump, 1 for mini, 2 for Heap, 3 for triage, 4 for full. Don't use 4 unless you know what you're doing.
               DOTNET_DbgMiniDumpName: $(Build.SourcesDirectory)\artifacts\log\Release\$(Build.BuildId)-%e-%p-%t.dmp

src/Compiler/Utilities/Caches.fs

@@ -194,12 +194,23 @@ type CacheOptions<'Key> =
     }
 
 module CacheOptions =
+    let forceImmediate =
+        try
+            Environment.GetEnvironmentVariable("FSharp_CacheEvictionImmediate") <> null
+        with _ ->
+            false
+
+    let defaultEvictionMode =
+        if forceImmediate then
+            EvictionMode.Immediate
+        else
+            EvictionMode.MailboxProcessor
 
     let getDefault comparer =
         {
             CacheOptions.TotalCapacity = 1024
             CacheOptions.HeadroomPercentage = 50
-            CacheOptions.EvictionMode = EvictionMode.MailboxProcessor
+            CacheOptions.EvictionMode = defaultEvictionMode
             CacheOptions.Comparer = comparer
         }
 

tests/Directory.Build.props

@@ -16,6 +16,7 @@
     <NoOptimizationData>false</NoOptimizationData>
     <NoInterfaceData>false</NoInterfaceData>
     <CompressMetadata>true</CompressMetadata>
+    <ServerGarbageCollection>true</ServerGarbageCollection>
   </PropertyGroup>
 
 </Project>

tests/FSharp.Test.Utilities/CompilerAssert.fs

@@ -376,23 +376,25 @@ module CompilerAssertHelpers =
         let setup = AppDomainSetup(ApplicationBase = thisAssemblyDirectory)
         let testCaseDomain = AppDomain.CreateDomain($"built app {assembly}", null, setup)
 
-        testCaseDomain.add_AssemblyResolve(fun _ args ->
+        let handler = ResolveEventHandler(fun _ args ->
             dependecies
             |> List.tryFind (fun path -> Path.GetFileNameWithoutExtension path = AssemblyName(args.Name).Name)
             |> Option.filter FileSystem.FileExistsShim
             |> Option.map Assembly.LoadFile
             |> Option.toObj
         )
 
+        testCaseDomain.add_AssemblyResolve handler
+
         let worker =
             (testCaseDomain.CreateInstanceFromAndUnwrap(typeof<Worker>.Assembly.CodeBase, typeof<Worker>.FullName)) :?> Worker
 
         let outcome, output, errors = worker.ExecuteTestCase assembly isFsx
         // Replay streams captured in appdomain.
         printf $"{output}"
         eprintf $"{errors}"
-        
-        AppDomain.Unload testCaseDomain
+
+        testCaseDomain.remove_AssemblyResolve handler
 
         outcome, output, errors
 

tests/FSharp.Test.Utilities/XunitHelpers.fs

@@ -202,6 +202,7 @@ module OneTimeSetup =
         log "Adding AssemblyResolver"
         AssemblyResolver.addResolver ()
     #endif
+        log $"Server GC enabled: {System.Runtime.GCSettings.IsServerGC}"
         log "Installing TestConsole redirection"
         TestConsole.install()