From ee28ad3c8fb0167b3d0c182316de20e099c74a03 Mon Sep 17 00:00:00 2001
From: Jimmy Byrd <jimmybyrd@gmail.com>
Date: Sat, 15 Jul 2023 10:48:59 -0400
Subject: [PATCH] Remove Async.SwitchToNewThreadCalls (#1144)

since https://github.com/dotnet/fsharp/issues/14899 got merged in FCS, it seems we don't hit threadpool exhaustion issues anymore
---
 src/FsAutoComplete.Core/CompilerServiceInterface.fs  | 12 ------------
 .../LspServers/AdaptiveFSharpLspServer.fs            |  1 +
 2 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/src/FsAutoComplete.Core/CompilerServiceInterface.fs b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
index 7f4bc9299..1ea00f523 100644
--- a/src/FsAutoComplete.Core/CompilerServiceInterface.fs
+++ b/src/FsAutoComplete.Core/CompilerServiceInterface.fs
@@ -165,8 +165,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
 
       let allFlags = Array.append [| "--targetprofile:mscorlib" |] fsiAdditionalArguments
 
-      do! Async.SwitchToNewThread()
-
       let! (opts, errors) =
         checker.GetProjectOptionsFromScript(
           UMX.untag file,
@@ -192,8 +190,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
       let allFlags =
         Array.append [| "--targetprofile:netstandard" |] fsiAdditionalArguments
 
-      do! Async.SwitchToNewThread()
-
       let! (opts, errors) =
         checker.GetProjectOptionsFromScript(
           UMX.untag file,
@@ -269,7 +265,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
       )
 
       let path = UMX.untag filePath
-      do! Async.SwitchToNewThread()
       return! checker.ParseFile(path, source, options)
     }
 
@@ -299,7 +294,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
       let path = UMX.untag filePath
 
       try
-        do! Async.SwitchToNewThread()
         let! (p, c) = checker.ParseAndCheckFileInProject(path, version, source, options, userOpName = opName)
 
         let parseErrors = p.Diagnostics |> Array.map (fun p -> p.Message)
@@ -394,8 +388,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
         >> Log.addContextDestructured "file" file
       )
 
-      do! Async.SwitchToNewThread()
-
       match FSharpCompilerServiceChecker.GetDependingProjects file options with
       | None -> return [||]
       | Some(opts, []) ->
@@ -407,7 +399,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
           opts :: dependentProjects
           |> List.map (fun (opts) ->
             async {
-              do! Async.SwitchToNewThread()
               let opts = clearProjectReferences opts
               let! res = checker.ParseAndCheckProject opts
               return res.GetUsesOfSymbol symbol
@@ -424,8 +415,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
         >> Log.addContextDestructured "file" file
       )
 
-      do! Async.SwitchToNewThread()
-
       return!
         checker.FindBackgroundReferencesInFile(
           file,
@@ -444,7 +433,6 @@ type FSharpCompilerServiceChecker(hasAnalyzers, typecheckCacheSize) =
         >> Log.addContextDestructured "file" fileName
       )
 
-      do! Async.SwitchToNewThread()
       let! parseResult = checker.ParseFile(UMX.untag fileName, source, options)
       return parseResult.GetNavigationItems().Declarations
     }
diff --git a/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs b/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
index 3321c2438..aa91a1933 100644
--- a/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
+++ b/src/FsAutoComplete/LspServers/AdaptiveFSharpLspServer.fs
@@ -385,6 +385,7 @@ type AdaptiveFSharpLspServer
 
           match parseAndCheck.GetCheckResults.ImplementationFile with
           | Some tast ->
+            // Since analyzers are not async, we need to switch to a new thread to not block threadpool
             do! Async.SwitchToNewThread()
 
             let res =