Adds more garbage collection settings (ionide#1896)

* Adds more garbage collection settings

* Adds back use of deprecated conserveMemory setting

Author: TheAngryByrd

release/package.json

@@ -532,7 +532,8 @@
         "FSharp.fsac.conserveMemory": {
           "default": false,
           "description": "Configures FsAutoComplete with settings intended to reduce memory consumption. Requires restart.",
-          "type": "boolean"
+          "type": "boolean",
+          "deprecationMessage": "This setting is deprecated. Use FSharp.fsac.gc.conserveMemory instead."
         },
         "FSharp.fsac.dotnetArgs": {
           "default": [],
@@ -542,6 +543,25 @@
           },
           "type": "array"
         },
+        "FSharp.fsac.gc.conserveMemory" : {
+          "markdownDescription": "Configures the garbage collector to [conserve memory](https://learn.microsoft.com/en-us/dotnet/core/runtime-config/garbage-collector#conserve-memory) at the expense of more frequent garbage collections and possibly longer pause times. Acceptable values are 0-9. Any non-zero value will allow the [Large Object Heap](https://learn.microsoft.com/en-us/dotnet/standard/garbage-collection/large-object-heap) to be compacted automatically if it has too much fragmentation. Requires restart.",
+          "type": "integer",
+          "minimum": 0,
+          "maximum": 9
+        },
+        "FSharp.fsac.gc.heapCount" : {
+          "default": 2,
+          "markdownDescription": "Limits the number of [heaps](https://learn.microsoft.com/en-us/dotnet/standard/garbage-collection/fundamentals#the-managed-heap) created by the garbage collector. Applies to server garbage collection only. See [Middle Ground between Server and Workstation GC](https://devblogs.microsoft.com/dotnet/middle-ground-between-server-and-workstation-gc/) for more details. This can allow FSAC to still benefit from Server garbage collection while still limiting the number of heaps. Requires restart.",
+          "type": "integer",
+          "required": [
+            "FSharp.fsac.gc.server"
+          ]
+        },
+        "FSharp.fsac.gc.server": {
+          "default": true,
+          "markdownDescription": "Configures whether the application uses workstation garbage collection or server garbage collection. See [Workstation vs Server Garbage Collection](https://devblogs.microsoft.com/premier-developer/understanding-different-gc-modes-with-concurrency-visualizer/#workstation-gc-vs-server-gc) for more details. Workstation will use less memory but Server will have more throughput. Requires restart.",
+          "type": "boolean"
+        },
         "FSharp.fsac.netCoreDllPath": {
           "default": "",
           "description": "The path to the \u0027fsautocomplete.dll\u0027, a directory containing TFM-specific versions of fsautocomplete.dll, or a directory containing fsautocomplete.dll. Useful for debugging a self-built FSAC. If a DLL is specified, uses it directly. If a directory is specified and it contains TFM-specific folders (net6.0, net7.0, etc) then that directory will be probed for the best TFM to use for the current runtime. This is useful when working with a local copy of FSAC, you can point directly to the bin/Debug or bin/Release folder and it\u0027ll Just Work. Finally, if a directory is specified and there are no TFM paths, then fsautocomplete.dll from that directory is used. Requires restart.",
@@ -1720,4 +1740,4 @@
     "url": "https://github.com/ionide/ionide-vscode-fsharp.git"
   },
   "version": "7.8.2"
-}
+}

src/Core/LanguageService.fs

@@ -632,7 +632,36 @@ Consider:
             let enableProjectGraph =
                 "FSharp.enableMSBuildProjectGraph" |> Configuration.get false
 
-            let conserveMemory = "FSharp.fsac.conserveMemory" |> Configuration.get false
+            let tryBool x =
+                // Boolean.TryParse generates: TypeError: e.match is not a function if we don't call toString first
+                match Boolean.TryParse(x.ToString()) with
+                | (true, v) -> Some v
+                | _ -> None
+
+            let tryInt x =
+                match Int32.TryParse(x.ToString()) with
+                | (true, v) -> Some v
+                | _ -> None
+
+            let oldgcConserveMemory =
+                "FSharp.fsac.conserveMemory"
+                |> Configuration.tryGet
+                |> Option.map string
+                |> Option.bind tryBool
+
+            let gcConserveMemory =
+                "FSharp.fsac.gc.conserveMemory" |> Configuration.tryGet |> Option.bind tryInt
+
+            let gcConserveMemory =
+                // prefer new setting, fallback to old, default is 0
+                match gcConserveMemory, oldgcConserveMemory with
+                | Some x, _ -> x
+                | None, Some true -> 9
+                | None, _ -> 0
+
+            let gcHeapCount = "FSharp.fsac.gc.heapCount" |> Configuration.get 2
+
+            let gcServer = "FSharp.fsac.gc.server" |> Configuration.get true
 
             let parallelReferenceResolution =
                 "FSharp.fsac.parallelReferenceResolution" |> Configuration.get false
@@ -788,8 +817,9 @@ Consider:
 
                     let fsacEnvVars =
                         [ yield! fsacEnvVars
-                          if conserveMemory then
-                              yield "DOTNET_GCConserveMemory", box "9"
+                          yield "DOTNET_GCHeapCount", box (gcHeapCount.ToString("X")) // Requires hexadecimal value
+                          yield "DOTNET_GCConserveMemory", box gcConserveMemory
+                          yield "DOTNET_GCServer", box gcServer
                           if parallelReferenceResolution then
                               yield "FCS_ParallelReferenceResolution", box "true" ]