fix: mitigate high CPU and thread explosion in large multi-module workspaces

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/index/SpringMetamodelIndex.java

@@ -29,47 +29,67 @@
 public class SpringMetamodelIndex {
 
 	private final ConcurrentMap<String, ProjectElement> projectRootElements;
+	private final ConcurrentMap<String, DocumentElement> docUriToDocument;
 
 	public SpringMetamodelIndex() {
 		projectRootElements = new ConcurrentHashMap<>();
+		docUriToDocument = new ConcurrentHashMap<>();
 	}
 
 	public void updateElements(String projectName, String docURI, SpringIndexElement[] elements) {
 		ProjectElement project = this.projectRootElements.computeIfAbsent(projectName, name -> new ProjectElement(name));
 		project.removeDocument(docURI);
-		
+
 		if (elements != null && elements.length > 0) {
 			DocumentElement document = new DocumentElement(docURI);
 			for (SpringIndexElement bean : elements) {
 				document.addChild(bean);
 			}
-			
+
 			project.addChild(document);
-		}	
-
+			docUriToDocument.put(docURI, document);
+		} else {
+			docUriToDocument.remove(docURI);
+		}
+
 	}
 
 	public void removeElements(String projectName, String docURI) {
 		ProjectElement project = projectRootElements.get(projectName);
 		if (project != null) {
 			project.removeDocument(docURI);
 		}
+		docUriToDocument.remove(docURI);
 	}
 
 	public void removeProject(String projectName) {
-		projectRootElements.remove(projectName);
+		this.projectRootElements.computeIfPresent(projectName, (name, project) -> {
+			for (SpringIndexElement child : project.getChildren()) {
+				if (child instanceof DocumentElement) {
+					docUriToDocument.remove(((DocumentElement) child).getDocURI());
+				}
+			}
+			return null;
+		});
 	}
 
 	public Collection<ProjectElement> getProjects() {
 		return Collections.unmodifiableCollection(this.projectRootElements.values());
 	}
 
 	public DocumentElement getDocument(String docURI) {
+		DocumentElement cached = docUriToDocument.get(docURI);
+		if (cached != null) {
+			return cached;
+		}
+		// Fallback to full traversal if not in cache (e.g. for pre-existing elements)
 		List<SpringIndexElement> rootNodes = new ArrayList<SpringIndexElement>(this.projectRootElements.values());
 		List<DocumentElement> documents = getNodesOfType(DocumentElement.class, rootNodes, document -> document.getDocURI().equals(docURI));
 
 		if (documents.size() == 1) {
-			return documents.get(0);
+			DocumentElement doc = documents.get(0);
+			docUriToDocument.putIfAbsent(docURI, doc);
+			return doc;
 		}
 		else {
 			return null;

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/java/commands/SpringIndexCommands.java

@@ -59,7 +59,7 @@ public SpringIndexCommands(SimpleLanguageServer server, SpringMetamodelIndex spr
 		this.modulithService = modulithService;
 		this.stereotypeCatalogRegistry = stereotypeCatalogRegistry;
 		this.sourceLinks = sourceLinks;
-		this.messageWorkerThreadPool = Executors.newCachedThreadPool();
+		this.messageWorkerThreadPool = Executors.newFixedThreadPool(4);
 
 		server.onCommand(SPRING_STRUCTURE_CMD, params -> {
 			return CompletableFuture.supplyAsync(() -> {

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/java/reconcilers/CompositeASTVisitor.java

@@ -71,14 +71,18 @@ public boolean visit(MethodDeclaration node) {
 	@Override
 	public void endVisit(MethodDeclaration node) {
 		for (ASTVisitor astVisitor : visitors) {
-			astVisitor.endVisit(node);
+			if (astVisitor != null) {
+				astVisitor.endVisit(node);
+			}
 		}
 	}
 
 	@Override
 	public void endVisit(CompilationUnit node) {
 		for (ASTVisitor astVisitor : visitors) {
-			astVisitor.endVisit(node);
+			if (astVisitor != null) {
+				astVisitor.endVisit(node);
+			}
 		}
 	}
 
@@ -141,7 +145,9 @@ private boolean delegateVisit(ASTNode node, Function<ASTVisitor, Boolean> visitF
 		}
 		boolean result = false;
 		for (ASTVisitor visitor : visitors) {
-			result |= visitFn.apply(visitor);
+			if (visitor != null) {
+				result |= visitFn.apply(visitor);
+			}
 		}
 		return result;
 	}

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/java/utils/CompilationUnitCache.java

@@ -83,7 +83,7 @@ public final class CompilationUnitCache implements DocumentContentProvider {
 	private final ReentrantReadWriteLock environmentCacheLock = new ReentrantReadWriteLock(true);
 	private CompletableFuture<Void> debounceClassFileChanges = CompletableFuture.completedFuture(null);
 
-	private final Executor createCuExecutorThreadPool = Executors.newCachedThreadPool();
+	private final Executor createCuExecutorThreadPool = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());
 
 	public CompilationUnitCache(JavaProjectFinder projectFinder, SimpleLanguageServer server, ProjectObserver projectObserver) {
 		this.projectFinder = projectFinder;

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/modulith/ModulithService.java

@@ -111,7 +111,7 @@ public ModulithService(
 		this.springIndexer = springIndexer;
 		this.springIndex = springIndex;
 		this.reconciler = reconciler;
-		this.executor = Executors.newCachedThreadPool();
+		this.executor = Executors.newFixedThreadPool(4);
 		this.autoTrackingProjects = false;
 
 		this.projectListener = new ProjectObserver.Listener() {