Add option to disable server gc

package.json

@@ -1462,17 +1462,22 @@
             "default": null,
             "description": "%configuration.dotnet.server.crashDumpPath%"
           },
+          "dotnet.server.suppressLspErrorToasts": {
+            "type": "boolean",
+            "default": false,
+            "description": "%configuration.dotnet.server.suppressLspErrorToasts%"
+          },
+          "dotnet.server.useServerGC": {
+            "type": "boolean",
+            "default": true,
+            "description": "%configuration.dotnet.server.useServerGC%"
+          },
           "dotnet.enableXamlTools": {
             "scope": "machine-overridable",
             "type": "boolean",
             "default": true,
             "description": "%configuration.dotnet.enableXamlTools%"
           },
-          "dotnet.server.suppressLspErrorToasts": {
-            "type": "boolean",
-            "default": false,
-            "description": "%configuration.dotnet.server.suppressLspErrorToasts%"
-          },
           "dotnet.projects.binaryLogPath": {
             "scope": "machine-overridable",
             "type": "string",

package.nls.json

@@ -34,8 +34,10 @@
   "configuration.dotnet.server.trace": "Sets the logging level for the language server",
   "configuration.dotnet.server.extensionPaths": "Override for path to language server --extension arguments",
   "configuration.dotnet.server.crashDumpPath": "Sets a folder path where crash dumps are written to if the language server crashes.  Must be writeable by the user.",
-  "configuration.dotnet.enableXamlTools": "Enables XAML tools when using C# Dev Kit",
   "configuration.dotnet.server.suppressLspErrorToasts": "Suppresses error toasts from showing up if the server encounters a recoverable error.",
+  "configuration.dotnet.server.useServerGC": "Configure the language server to use .NET server garbage collection.  Server garbage collection generally provides better performance at the expensive of higher memory consumption.",
+  "configuration.dotnet.enableXamlTools": "Enables XAML tools when using C# Dev Kit",
+  "configuration.dotnet.enableXamlToolsPreview": "[Experimental] Enables XAML tools when using C# Dev Kit",
   "configuration.dotnet.projects.enableAutomaticRestore": "Enables automatic NuGet restore if the extension detects assets are missing.",
   "configuration.dotnet.projects.binaryLogPath": "Sets a path where MSBuild binary logs are written to when loading projects, to help diagnose loading errors.",
   "configuration.dotnet.preferCSharpExtension": "Forces projects to load with the C# extension only.  This can be useful when using legacy project types that are not supported by C# Dev Kit. (Requires window reload)",

src/lsptoolshost/roslynLanguageServer.ts

@@ -607,7 +607,9 @@ export class RoslynLanguageServer {
             args.push('--extension', extensionPath);
         }
 
-        if (logLevel && [Trace.Messages, Trace.Verbose].includes(this.GetTraceLevel(logLevel))) {
+        const isTraceLogLevel = logLevel && [Trace.Messages, Trace.Verbose].includes(this.GetTraceLevel(logLevel));
+
+        if (isTraceLogLevel) {
             _channel.appendLine(`Starting server at ${serverPath}`);
         }
 
@@ -616,6 +618,15 @@ export class RoslynLanguageServer {
 
         args.push('--extensionLogDirectory', context.logUri.fsPath);
 
+        const env = dotnetInfo.env;
+        if (!languageServerOptions.useServerGC) {
+            // The server by default uses serverGC, if the user opts out we need to set the environment variable to disable it.
+            env.DOTNET_gcServer = '0';
+            if (isTraceLogLevel) {
+                _channel.appendLine('ServerGC disabled');
+            }
+        }
+
         let childProcess: cp.ChildProcessWithoutNullStreams;
         const cpOptions: cp.SpawnOptionsWithoutStdio = {
             detached: true,

src/shared/options.ts

@@ -80,6 +80,7 @@ export interface LanguageServerOptions {
     readonly componentPaths: { [key: string]: string } | null;
     readonly enableXamlTools: boolean;
     readonly suppressLspErrorToasts: boolean;
+    readonly useServerGC: boolean;
 }
 
 export interface RazorOptions {
@@ -410,6 +411,9 @@ class LanguageServerOptionsImpl implements LanguageServerOptions {
     public get suppressLspErrorToasts() {
         return readOption<boolean>('dotnet.server.suppressLspErrorToasts', false);
     }
+    public get useServerGC() {
+        return readOption<boolean>('dotnet.server.useServerGC', true);
+    }
 }
 
 class RazorOptionsImpl implements RazorOptions {
@@ -508,4 +512,5 @@ export const LanguageServerOptionsThatTriggerReload: ReadonlyArray<keyof Languag
     'preferCSharpExtension',
     'componentPaths',
     'enableXamlTools',
+    'useServerGC',
 ];