Make sure builtins are properly set after modules reload

src/Analysis/Ast/Impl/Modules/PythonModule.cs

@@ -215,10 +215,10 @@ protected virtual string LoadContent() {
             return null; // Keep content as null so module can be loaded later.
         }
 
-        private void InitializeContent(string content) {
+        private void InitializeContent(string content, int version = 0) {
             bool startParse;
             lock (AnalysisLock) {
-                LoadContent(content);
+                LoadContent(content, version);
 
                 startParse = ContentState < State.Parsing && _parsingTask == null;
                 if (startParse) {
@@ -231,11 +231,11 @@ private void InitializeContent(string content) {
             }
         }
 
-        private void LoadContent(string content) {
+        private void LoadContent(string content, int version) {
             if (ContentState < State.Loading) {
                 try {
                     content = content ?? LoadContent();
-                    _buffer.Reset(0, content);
+                    _buffer.Reset(version, content);
                     ContentState = State.Loaded;
                 } catch (IOException) { } catch (UnauthorizedAccessException) { }
             }
@@ -330,7 +330,8 @@ public void Update(IEnumerable<DocumentChange> changes) {
         public void Reset(string content) {
             lock (AnalysisLock) {
                 if (content != Content) {
-                    InitializeContent(content);
+                    ContentState = State.None;
+                    InitializeContent(content, _buffer.Version + 1);
                 }
             }
         }

src/Analysis/Ast/Impl/Modules/Resolution/MainModuleResolution.cs

@@ -180,7 +180,11 @@ internal async Task LoadBuiltinTypesAsync(CancellationToken cancellationToken =
             await BuiltinsModule.LoadAndAnalyzeAsync(cancellationToken);
 
             Check.InvalidOperation(!(BuiltinsModule.Analysis is EmptyAnalysis), "After await");
+            // Add built-in module names
+            SetBuiltinModuleNames();
+        }
 
+        private void SetBuiltinModuleNames() {
             // Add built-in module names
             var builtinModuleNamesMember = BuiltinsModule.GetAnyMember("__builtin_module_names__");
             if (builtinModuleNamesMember.TryGetConstant<string>(out var s)) {
@@ -203,6 +207,7 @@ public async Task ReloadAsync(CancellationToken cancellationToken = default) {
             Modules[BuiltinModuleName] = builtins;
 
             PathResolver = new PathResolver(_interpreter.LanguageVersion);
+            SetBuiltinModuleNames();
 
             var addedRoots = new HashSet<string>();
             addedRoots.UnionWith(PathResolver.SetRoot(_root));

src/LanguageServer/Impl/Implementation/Server.cs

@@ -40,12 +40,16 @@ public sealed partial class Server : IDisposable {
         private readonly DisposableBag _disposableBag = DisposableBag.Create<Server>();
         private readonly CancellationTokenSource _shutdownCts = new CancellationTokenSource();
         private readonly IServiceManager _services;
+        private readonly object _reloadLock = new object();
 
         private IPythonInterpreter _interpreter;
         private IRunningDocumentTable _rdt;
         private ClientCapabilities _clientCaps;
         private ILogger _log;
         private IIndexManager _indexManager;
+        private string _rootDir;
+        private DateTime _lastPackageReload = DateTime.Now;
+
 
         public Server(IServiceManager services) {
             _services = services;
@@ -65,25 +69,26 @@ public Server(IServiceManager services) {
         public void Dispose() => _disposableBag.TryDispose();
 
         #region Client message handling
+
         private InitializeResult GetInitializeResult() => new InitializeResult {
             capabilities = new ServerCapabilities {
                 textDocumentSync = new TextDocumentSyncOptions {
                     openClose = true,
                     change = TextDocumentSyncKind.Incremental
                 },
                 completionProvider = new CompletionOptions {
-                    triggerCharacters = new[] { "." }
+                    triggerCharacters = new[] {"."}
                 },
                 hoverProvider = true,
-                signatureHelpProvider = new SignatureHelpOptions { triggerCharacters = new[] { "(", ",", ")" } },
+                signatureHelpProvider = new SignatureHelpOptions {triggerCharacters = new[] {"(", ",", ")"}},
                 definitionProvider = true,
                 referencesProvider = true,
                 workspaceSymbolProvider = true,
                 documentSymbolProvider = true,
                 renameProvider = true,
                 documentOnTypeFormattingProvider = new DocumentOnTypeFormattingOptions {
                     firstTriggerCharacter = "\n",
-                    moreTriggerCharacter = new[] { ";", ":" }
+                    moreTriggerCharacter = new[] {";", ":"}
                 },
             }
         };
@@ -121,10 +126,10 @@ public async Task<InitializeResult> InitializeAsync(InitializeParams @params, Ca
             _services.AddService(_interpreter);
 
             var fileSystem = _services.GetService<IFileSystem>();
-            _indexManager = new IndexManager(fileSystem, _interpreter.LanguageVersion, rootDir,
-                                            @params.initializationOptions.includeFiles,
-                                            @params.initializationOptions.excludeFiles,
-                                            _services.GetService<IIdleTimeService>());
+            _indexManager = new IndexManager(fileSystem, _interpreter.LanguageVersion, _rootDir,
+                @params.initializationOptions.includeFiles,
+                @params.initializationOptions.excludeFiles,
+                _services.GetService<IIdleTimeService>());
             _services.AddService(_indexManager);
             _disposableBag.Add(_indexManager);
 
@@ -158,22 +163,25 @@ public void DidChangeConfiguration(DidChangeConfigurationParams @params, Cancell
                     if (HandleConfigurationChanges(settings)) {
                         RestartAnalysis();
                     }
+
                     break;
                 }
                 default:
                     _log?.Log(TraceEventType.Error, "change configuration notification sent unsupported settings");
                     break;
             }
         }
+
         #endregion
 
         #region Private Helpers
+
         private void DisplayStartupInfo() {
             _log?.Log(TraceEventType.Information, Resources.LanguageServerVersion.FormatInvariant(Assembly.GetExecutingAssembly().GetName().Version));
             _log?.Log(TraceEventType.Information,
                 string.IsNullOrEmpty(_interpreter.Configuration.InterpreterPath)
-                ? Resources.InitializingForGenericInterpreter
-                : Resources.InitializingForPythonInterpreter.FormatInvariant(_interpreter.Configuration.InterpreterPath));
+                    ? Resources.InitializingForGenericInterpreter
+                    : Resources.InitializingForPythonInterpreter.FormatInvariant(_interpreter.Configuration.InterpreterPath));
         }
 
         private bool HandleConfigurationChanges(ServerSettings newSettings) {
@@ -212,25 +220,31 @@ private IDocumentationSource ChooseDocumentationSource(string[] kinds) {
 
             return new PlainTextDocumentationSource();
         }
+
         #endregion
 
         public void NotifyPackagesChanged(CancellationToken cancellationToken) {
-            var interpreter = _services.GetService<IPythonInterpreter>();
-            _log?.Log(TraceEventType.Information, Resources.ReloadingModules);
-            // No need to reload typeshed resolution since it is a static storage.
-            // User does can add stubs while application is running, but it is
-            // by design at this time that the app should be restarted.
-            interpreter.ModuleResolution.ReloadAsync(cancellationToken).ContinueWith(t => {
-                _log?.Log(TraceEventType.Information, Resources.Done);
-                _log?.Log(TraceEventType.Information, Resources.AnalysisRestarted);
-                RestartAnalysis();
-            }, cancellationToken).DoNotWait();
-
+            lock (_reloadLock) {
+                if ((DateTime.Now - _lastPackageReload).TotalMilliseconds > 10000) {
+                    var interpreter = _services.GetService<IPythonInterpreter>();
+                    _log?.Log(TraceEventType.Information, Resources.ReloadingModules);
+                    // No need to reload typeshed resolution since it is a static storage.
+                    // User does can add stubs while application is running, but it is
+                    // by design at this time that the app should be restarted.
+                    interpreter.ModuleResolution.ReloadAsync(cancellationToken).ContinueWith(t => {
+                        _log?.Log(TraceEventType.Information, Resources.Done);
+                        _log?.Log(TraceEventType.Information, Resources.AnalysisRestarted);
+                        RestartAnalysis();
+                    }, cancellationToken).DoNotWait();
+                }
+            }
         }
 
         private void RestartAnalysis() {
-            foreach (var doc in _rdt) {
-                doc.Reset(null);
+            lock (_reloadLock) {
+                foreach (var doc in _rdt) {
+                    doc.Reset(null);
+                }
             }
         }
     }

src/LanguageServer/Impl/PathsWatcher.cs

@@ -80,7 +80,7 @@ private void OnChanged(object sender, FileSystemEventArgs e) {
             // if there is massive change to the file structure.
             lock (_lock) {
                 _changedSinceLastTick = true;
-                _throttleTimer = _throttleTimer ?? new Timer(TimerProc, null, 500, 500);
+                _throttleTimer = _throttleTimer ?? new Timer(TimerProc, null, 2000, 2000);
             }
         }