12 files changed, 248 insertions, 191 deletions

diff --git a/TODOS.md b/TODOS.md
index 8955db3..dc622ec 100644
--- a/TODOS.md
+++ b/TODOS.md
@@ -6,4 +6,7 @@
 ## Navigation
 - Go-to-subclasses
 - Test coverage codelens
-- Go-to-implementation for overridden methods
\ No newline at end of file
+- Go-to-implementation for overridden methods
+
+## Bugs 
+- Imports MyEnum.* unnecessarily
\ No newline at end of file
diff --git a/lib/extension.ts b/lib/extension.ts
index 3b1a867..68b3f11 100644
--- a/lib/extension.ts
+++ b/lib/extension.ts
@@ -219,7 +219,7 @@ function platformSpecificLauncher(): string[] {
 		case 'win32':
             return ['dist', 'windows', 'bin', 'launcher'];
 
-		case 'darwin':
+        case 'darwin':
             return ['dist', 'mac', 'bin', 'launcher'];
 	}
 
@@ -245,7 +245,14 @@ function visualVmConfig(context: ExtensionContext): ServerOptions {
         '-Xverify:none', // helps VisualVM avoid 'error 62'
         '-Xdebug',
         // '-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005',
-        'org.javacs.Main'
+        'org.javacs.Main',
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.api=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.code=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.comp=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.main=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.tree=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.model=javacs",
+        "--add-exports", "jdk.compiler/com.sun.tools.javac.util=javacs",
     ];
     
     console.log(javaExecutablePath + ' ' + args.join(' '));
diff --git a/scripts/link_mac.sh b/scripts/link_mac.sh
index ce29108..72223f2 100755
--- a/scripts/link_mac.sh
+++ b/scripts/link_mac.sh
@@ -21,4 +21,10 @@ $JAVA_HOME/bin/jlink \
   --add-modules gson,javacs \
   --launcher launcher=javacs/org.javacs.Main \
   --output dist/mac \
-  --compress 2 
\ No newline at end of file
+  --compress 2 
+
+# Restore launcher
+echo '#!/bin/sh
+JLINK_VM_OPTIONS="--add-exports jdk.compiler/com.sun.tools.javac.api=javacs --add-exports jdk.compiler/com.sun.tools.javac.code=javacs --add-exports jdk.compiler/com.sun.tools.javac.comp=javacs --add-exports jdk.compiler/com.sun.tools.javac.main=javacs --add-exports jdk.compiler/com.sun.tools.javac.tree=javacs --add-exports jdk.compiler/com.sun.tools.javac.model=javacs --add-exports jdk.compiler/com.sun.tools.javac.util=javacs"
+DIR=`dirname $0`
+$DIR/java $JLINK_VM_OPTIONS -m javacs/org.javacs.Main $@' > dist/mac/bin/launcher
\ No newline at end of file
diff --git a/scripts/link_windows.sh b/scripts/link_windows.sh
index 3177db5..1f855c9 100755
--- a/scripts/link_windows.sh
+++ b/scripts/link_windows.sh
@@ -35,4 +35,15 @@ $REAL_JAVA_HOME/bin/jlink \
   --add-modules gson,javacs \
   --launcher launcher=javacs/org.javacs.Main \
   --output dist/windows \
-  --compress 2 
\ No newline at end of file
+  --compress 2 
+
+# Restore launcher
+echo '#!/bin/sh
+JLINK_VM_OPTIONS="--add-exports jdk.compiler/com.sun.tools.javac.api=javacs --add-exports jdk.compiler/com.sun.tools.javac.code=javacs --add-exports jdk.compiler/com.sun.tools.javac.comp=javacs --add-exports jdk.compiler/com.sun.tools.javac.main=javacs --add-exports jdk.compiler/com.sun.tools.javac.tree=javacs --add-exports jdk.compiler/com.sun.tools.javac.model=javacs --add-exports jdk.compiler/com.sun.tools.javac.util=javacs"
+DIR=`dirname $0`
+$DIR/java $JLINK_VM_OPTIONS -m javacs/org.javacs.Main $@' > dist/windows/bin/launcher
+
+echo '@echo off
+set JLINK_VM_OPTIONS="--add-exports jdk.compiler/com.sun.tools.javac.api=javacs --add-exports jdk.compiler/com.sun.tools.javac.code=javacs --add-exports jdk.compiler/com.sun.tools.javac.comp=javacs --add-exports jdk.compiler/com.sun.tools.javac.main=javacs --add-exports jdk.compiler/com.sun.tools.javac.tree=javacs --add-exports jdk.compiler/com.sun.tools.javac.model=javacs --add-exports jdk.compiler/com.sun.tools.javac.util=javacs"
+set DIR=%~dp0
+"%DIR%\java" %JLINK_VM_OPTIONS% -m javacs/org.javacs.Main %*' > dist/windows/bin/launcher.bat
\ No newline at end of file
diff --git a/src/main/java/org/javacs/CompileBatch.java b/src/main/java/org/javacs/CompileBatch.java
index de6988c..ddfb505 100644
--- a/src/main/java/org/javacs/CompileBatch.java
+++ b/src/main/java/org/javacs/CompileBatch.java
@@ -12,10 +12,10 @@ import javax.lang.model.util.*;
 import javax.tools.*;
 import org.javacs.lsp.Range;
 
-public class CompileBatch {
+public class CompileBatch implements AutoCloseable {
     private final JavaCompilerService parent;
     private final ReportProgress progress;
-    private final JavacTask task;
+    private final TaskPool.Borrow borrow;
     private final Trees trees;
     private final Elements elements;
     private final Types types;
@@ -24,14 +24,14 @@ public class CompileBatch {
     CompileBatch(JavaCompilerService parent, Collection<? extends JavaFileObject> files, ReportProgress progress) {
         this.parent = parent;
         this.progress = progress;
-        this.task = batchTask(parent, files);
-        this.trees = Trees.instance(task);
-        this.elements = task.getElements();
-        this.types = task.getTypes();
+        this.borrow = batchTask(parent, files);
+        this.trees = Trees.instance(borrow.task);
+        this.elements = borrow.task.getElements();
+        this.types = borrow.task.getTypes();
         this.roots = new ArrayList<CompilationUnitTree>();
         // Print timing information for optimization
         var profiler = new Profiler();
-        task.addTaskListener(profiler);
+        borrow.task.addTaskListener(profiler);
         // Show progress message through the UI
         class CountFiles implements TaskListener {
             Set<URI> parse = new HashSet<>(), enter = new HashSet<>(), analyze = new HashSet<>();
@@ -59,35 +59,39 @@ public class CompileBatch {
                 }
             }
         }
-        task.addTaskListener(new CountFiles());
+        borrow.task.addTaskListener(new CountFiles());
         // Compile all roots
         try {
-            for (var t : task.parse()) roots.add(t);
-            // The results of task.analyze() are unreliable when errors are present
+            for (var t : borrow.task.parse()) roots.add(t);
+            // The results of borrow.task.analyze() are unreliable when errors are present
             // You can get at `Element` values using `Trees`
-            task.analyze();
+            borrow.task.analyze();
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
         profiler.print();
     }
 
-    static JavacTask batchTask(JavaCompilerService parent, Collection<? extends JavaFileObject> sources) {
+    @Override
+    public void close() {
+        borrow.close();
+    }
+
+    static TaskPool.Borrow batchTask(JavaCompilerService parent, Collection<? extends JavaFileObject> sources) {
         parent.diags.clear();
-        return (JavacTask)
-                parent.compiler.getTask(
-                        null,
-                        parent.fileManager,
-                        parent.diags::add,
-                        JavaCompilerService.options(parent.classPath),
-                        Collections.emptyList(),
-                        sources);
+        return parent.compiler.getTask(
+                null,
+                parent.fileManager,
+                parent.diags::add,
+                JavaCompilerService.options(parent.classPath),
+                Collections.emptyList(),
+                sources);
     }
 
     public Optional<Element> element(URI uri, int line, int character) {
         for (var root : roots) {
             if (root.getSourceFile().toUri().equals(uri)) {
-                var path = CompileFocus.findPath(task, root, line, character);
+                var path = CompileFocus.findPath(borrow.task, root, line, character);
                 var el = trees.getElement(path);
                 return Optional.ofNullable(el);
             }
@@ -171,7 +175,7 @@ public class CompileBatch {
         // Otherwise, scan roots for references
         List<TreePath> list = new ArrayList<TreePath>();
         var map = Map.of(to, list);
-        var finder = new FindReferences(task);
+        var finder = new FindReferences(borrow.task);
         for (var r : roots) {
             finder.scan(r, map);
         }
@@ -207,7 +211,7 @@ public class CompileBatch {
     public Index index(URI from, List<Element> declarations) {
         for (var r : roots) {
             if (r.getSourceFile().toUri().equals(from)) {
-                return new Index(task, r, parent.diags, declarations);
+                return new Index(borrow.task, r, parent.diags, declarations);
             }
         }
         throw new RuntimeException(from + " is not in compiled batch");
@@ -216,7 +220,7 @@ public class CompileBatch {
     public Optional<Range> range(TreePath path) {
         var uri = path.getCompilationUnit().getSourceFile().toUri();
         var contents = FileStore.contents(uri);
-        return ParseFile.range(task, contents, path);
+        return ParseFile.range(borrow.task, contents, path);
     }
 
     private static final Logger LOG = Logger.getLogger("main");
diff --git a/src/main/java/org/javacs/CompileFile.java b/src/main/java/org/javacs/CompileFile.java
index 46029ae..bbe7b47 100644
--- a/src/main/java/org/javacs/CompileFile.java
+++ b/src/main/java/org/javacs/CompileFile.java
@@ -10,11 +10,11 @@ import java.util.logging.Logger;
 import javax.lang.model.element.*;
 import org.javacs.lsp.*;
 
-public class CompileFile {
+public class CompileFile implements AutoCloseable {
     private final JavaCompilerService parent;
     public final URI file;
     public final String contents;
-    private final JavacTask task;
+    private final TaskPool.Borrow borrow;
     private final Trees trees;
     public final CompilationUnitTree root;
 
@@ -22,21 +22,26 @@ public class CompileFile {
         this.parent = parent;
         this.file = file;
         this.contents = FileStore.contents(file);
-        this.task = CompileFocus.singleFileTask(parent, file, contents);
-        this.trees = Trees.instance(task);
+        this.borrow = CompileFocus.singleFileTask(parent, file, contents);
+        this.trees = Trees.instance(borrow.task);
         var profiler = new Profiler();
-        task.addTaskListener(profiler);
+        borrow.task.addTaskListener(profiler);
         try {
-            this.root = task.parse().iterator().next();
-            // The results of task.analyze() are unreliable when errors are present
+            this.root = borrow.task.parse().iterator().next();
+            // The results of borrow.task.analyze() are unreliable when errors are present
             // You can get at `Element` values using `Trees`
-            task.analyze();
+            borrow.task.analyze();
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
         profiler.print();
     }
 
+    @Override
+    public void close() {
+        borrow.close();
+    }
+
     public SourcePositions sourcePositions() {
         return trees.getSourcePositions();
     }
@@ -57,14 +62,14 @@ public class CompileFile {
     }
 
     public Index index(List<Element> declarations) {
-        return new Index(task, root, parent.diags, declarations);
+        return new Index(borrow.task, root, parent.diags, declarations);
     }
 
     public Optional<Element> element(int line, int character) {
         // LOG.info(String.format("Looking for element at %s(%d,%d)...", file.getPath(), line, character));
 
         // First, look for a tree path
-        var path = CompileFocus.findPath(task, root, line, character);
+        var path = CompileFocus.findPath(borrow.task, root, line, character);
         if (path == null) {
             // LOG.info("...found nothing");
             return Optional.empty();
@@ -132,12 +137,12 @@ public class CompileFile {
     }
 
     public Optional<Range> range(TreePath path) {
-        return ParseFile.range(task, contents, path);
+        return ParseFile.range(borrow.task, contents, path);
     }
 
     private List<Element> overrides(ExecutableElement method) {
-        var elements = task.getElements();
-        var types = task.getTypes();
+        var elements = borrow.task.getElements();
+        var types = borrow.task.getTypes();
         var results = new ArrayList<Element>();
         var enclosingClass = (TypeElement) method.getEnclosingElement();
         var enclosingType = enclosingClass.asType();
@@ -219,7 +224,7 @@ public class CompileFile {
         classes.addAll(parent.classPathClasses);
         var fixes = Parser.resolveSymbols(unresolved, sourcePathImports, classes);
         // Figure out which existing imports are actually used
-        var trees = Trees.instance(task);
+        var trees = Trees.instance(borrow.task);
         var references = new HashSet<String>();
         class FindUsedImports extends TreePathScanner<Void, Void> {
             @Override
diff --git a/src/main/java/org/javacs/CompileFocus.java b/src/main/java/org/javacs/CompileFocus.java
index 38a71d4..c1df941 100644
--- a/src/main/java/org/javacs/CompileFocus.java
+++ b/src/main/java/org/javacs/CompileFocus.java
@@ -18,14 +18,14 @@ import javax.lang.model.util.Types;
 import javax.tools.JavaFileObject;
 import javax.tools.StandardLocation;
 
-public class CompileFocus {
+public class CompileFocus implements AutoCloseable {
     public static final int MAX_COMPLETION_ITEMS = 50;
 
     private final JavaCompilerService parent;
     private final URI file;
     private final String contents;
     private final int line, character;
-    private final JavacTask task;
+    private final TaskPool.Borrow borrow;
     private final Trees trees;
     private final Types types;
     private final CompilationUnitTree root;
@@ -37,35 +37,40 @@ public class CompileFocus {
         this.contents = Pruner.prune(file, line, character);
         this.line = line;
         this.character = character;
-        this.task = singleFileTask(parent, file, this.contents);
-        this.trees = Trees.instance(task);
-        this.types = task.getTypes();
+        this.borrow = singleFileTask(parent, file, this.contents);
+        this.trees = Trees.instance(borrow.task);
+        this.types = borrow.task.getTypes();
 
         var profiler = new Profiler();
-        task.addTaskListener(profiler);
+        borrow.task.addTaskListener(profiler);
         try {
-            this.root = task.parse().iterator().next();
+            this.root = borrow.task.parse().iterator().next();
             // The results of task.analyze() are unreliable when errors are present
             // You can get at `Element` values using `Trees`
-            task.analyze();
+            borrow.task.analyze();
         } catch (IOException e) {
             throw new RuntimeException(e);
         }
         profiler.print();
-        this.path = findPath(task, root, line, character);
+        this.path = findPath(borrow.task, root, line, character);
     }
 
+    @Override
+    public void close() {
+        borrow.close();
+    }
+
+    // TODO this is highlighting incorrectly
     /** Create a task that compiles a single file */
-    static JavacTask singleFileTask(JavaCompilerService parent, URI file, String contents) {
+    static TaskPool.Borrow singleFileTask(JavaCompilerService parent, URI file, String contents) {
         parent.diags.clear();
-        return (JavacTask)
-                parent.compiler.getTask(
-                        null,
-                        parent.fileManager,
-                        parent.diags::add,
-                        JavaCompilerService.options(parent.classPath),
-                        Collections.emptyList(),
-                        List.of(new SourceFileObject(file, contents)));
+        return parent.compiler.getTask(
+                null,
+                parent.fileManager,
+                parent.diags::add,
+                JavaCompilerService.options(parent.classPath),
+                Collections.emptyList(),
+                List.of(new SourceFileObject(file, contents)));
     }
 
     /** Find the smallest element that includes the cursor */
@@ -203,8 +208,12 @@ public class CompileFocus {
 
         // Get members of switched type
         var type = trees.getTypeMirror(path);
+        if (type == null) {
+            LOG.info("...no type at " + leaf.getExpression());
+            return Collections.emptyList();
+        }
         LOG.info(String.format("...switched expression has type `%s`", type));
-        var types = task.getTypes();
+        var types = borrow.task.getTypes();
         var definition = types.asElement(type);
         if (definition == null) {
             LOG.info("...type has no definition, completing identifiers instead");
@@ -221,7 +230,7 @@ public class CompileFocus {
 
     /** Find all members of expression ending at line:character */
     public List<Completion> completeMembers(boolean isReference) {
-        var types = task.getTypes();
+        var types = borrow.task.getTypes();
         var scope = trees.getScope(path);
         var element = trees.getElement(path);
 
@@ -426,7 +435,7 @@ public class CompileFocus {
     }
 
     private void collectSuperMethods(TypeMirror thisType, List<ExecutableElement> result) {
-        var types = task.getTypes();
+        var types = borrow.task.getTypes();
 
         for (var superType : types.directSupertypes(thisType)) {
             if (superType instanceof DeclaredType) {
@@ -472,7 +481,7 @@ public class CompileFocus {
         collectSupers(t, types);
         // Object type is not included by default
         // We need to add it to get members like .equals(other) and .hashCode()
-        types.add(task.getElements().getTypeElement("java.lang.Object").asType());
+        types.add(borrow.task.getElements().getTypeElement("java.lang.Object").asType());
         return types;
     }
 
@@ -514,7 +523,7 @@ public class CompileFocus {
 
     /** Find all identifiers in scope at line:character */
     List<Element> scopeMembers(String partialName) {
-        var types = task.getTypes();
+        var types = borrow.task.getTypes();
         var start = trees.getScope(path);
 
         class Walk {
diff --git a/src/main/java/org/javacs/JavaCompilerService.java b/src/main/java/org/javacs/JavaCompilerService.java
index 8dfeaf8..afa0906 100644
--- a/src/main/java/org/javacs/JavaCompilerService.java
+++ b/src/main/java/org/javacs/JavaCompilerService.java
@@ -16,7 +16,7 @@ import javax.tools.*;
 public class JavaCompilerService {
     // Not modifiable! If you want to edit these, you need to create a new instance
     final Set<Path> classPath, docPath;
-    final JavaCompiler compiler = ServiceLoader.load(JavaCompiler.class).iterator().next();
+    final TaskPool compiler = new TaskPool(10);
     final Docs docs;
     final Set<String> jdkClasses = Classes.jdkTopLevelClasses(), classPathClasses;
     // Diagnostics from the last compilation task
@@ -40,7 +40,6 @@ public class JavaCompilerService {
         this.docs = new Docs(docPath);
         this.classPathClasses = Classes.classPathTopLevelClasses(classPath);
         this.fileManager = new SourceFileManager();
-        ;
     }
 
     /** Combine source path or class path entries using the system separator, for example ':' in unix */
@@ -121,46 +120,46 @@ public class JavaCompilerService {
 
         // Create task
         var options = options(classPath);
-        var task =
-                (JavacTask) compiler.getTask(null, fileManager, diags::add, options, Collections.emptyList(), sources);
-        var trees = Trees.instance(task);
-
-        // Print timing information for optimization
-        var profiler = new Profiler();
-        task.addTaskListener(profiler);
-
-        // Run compilation
-        diags.clear();
-        Iterable<? extends CompilationUnitTree> roots;
-        try {
-            roots = task.parse();
-            task.analyze();
-        } catch (IOException e) {
-            throw new RuntimeException(e);
-        }
-        profiler.print();
-        LOG.info(String.format("...found %d errors", diags.size()));
-
-        // Check for unused privates
-        for (var r : roots) {
-            var warnUnused = new WarnUnused(task);
-            warnUnused.scan(r, null);
-            for (var unusedEl : warnUnused.notUsed()) {
-                var path = trees.getPath(unusedEl);
-                var message = String.format("`%s` is not used", unusedEl.getSimpleName());
-                Diagnostic.Kind kind;
-                if (unusedEl instanceof ExecutableElement || unusedEl instanceof TypeElement) {
-                    kind = Diagnostic.Kind.OTHER;
-                } else {
-                    kind = Diagnostic.Kind.WARNING;
+        try (var borrow = compiler.getTask(null, fileManager, diags::add, options, Collections.emptyList(), sources)) {
+            var trees = Trees.instance(borrow.task);
+
+            // Print timing information for optimization
+            var profiler = new Profiler();
+            borrow.task.addTaskListener(profiler);
+
+            // Run compilation
+            diags.clear();
+            Iterable<? extends CompilationUnitTree> roots;
+            try {
+                roots = borrow.task.parse();
+                borrow.task.analyze();
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+            profiler.print();
+            LOG.info(String.format("...found %d errors", diags.size()));
+
+            // Check for unused privates
+            for (var r : roots) {
+                var warnUnused = new WarnUnused(borrow.task);
+                warnUnused.scan(r, null);
+                for (var unusedEl : warnUnused.notUsed()) {
+                    var path = trees.getPath(unusedEl);
+                    var message = String.format("`%s` is not used", unusedEl.getSimpleName());
+                    Diagnostic.Kind kind;
+                    if (unusedEl instanceof ExecutableElement || unusedEl instanceof TypeElement) {
+                        kind = Diagnostic.Kind.OTHER;
+                    } else {
+                        kind = Diagnostic.Kind.WARNING;
+                    }
+                    diags.add(new Warning(borrow.task, path, kind, "unused", message));
                 }
-                diags.add(new Warning(task, path, kind, "unused", message));
             }
-        }
-        // TODO hint fields that could be final
-        // TODO hint unused exception
+            // TODO hint fields that could be final
+            // TODO hint unused exception
 
-        return Collections.unmodifiableList(new ArrayList<>(diags));
+            return Collections.unmodifiableList(new ArrayList<>(diags));
+        }
     }
 
     public Set<URI> potentialDefinitions(Element to) {
diff --git a/src/main/java/org/javacs/JavaLanguageServer.java b/src/main/java/org/javacs/JavaLanguageServer.java
index 780d8e5..b1d9894 100644
--- a/src/main/java/org/javacs/JavaLanguageServer.java
+++ b/src/main/java/org/javacs/JavaLanguageServer.java
@@ -351,35 +351,34 @@ class JavaLanguageServer extends LanguageServer {
         }
         // Compile again, focusing on a region that depends on what type of completion we want to do
         var ctx = maybeCtx.get();
-        // TODO CompileFocus should have a "patch" mechanism where we recompile the current file without creating a new
-        // task
-        var focus = compiler.compileFocus(uri, ctx.line, ctx.character);
-        // Do a specific type of completion
         List<Completion> cs;
         boolean isIncomplete;
-        switch (ctx.kind) {
-            case MemberSelect:
-                cs = focus.completeMembers(false);
-                isIncomplete = false;
-                break;
-            case MemberReference:
-                cs = focus.completeMembers(true);
-                isIncomplete = false;
-                break;
-            case Identifier:
-                cs = focus.completeIdentifiers(ctx.inClass, ctx.inMethod, ctx.partialName);
-                isIncomplete = cs.size() >= CompileFocus.MAX_COMPLETION_ITEMS;
-                break;
-            case Annotation:
-                cs = focus.completeAnnotations(ctx.partialName);
-                isIncomplete = cs.size() >= CompileFocus.MAX_COMPLETION_ITEMS;
-                break;
-            case Case:
-                cs = focus.completeCases();
-                isIncomplete = false;
-                break;
-            default:
-                throw new RuntimeException("Unexpected completion context " + ctx.kind);
+        try (var focus = compiler.compileFocus(uri, ctx.line, ctx.character)) {
+            // Do a specific type of completion
+            switch (ctx.kind) {
+                case MemberSelect:
+                    cs = focus.completeMembers(false);
+                    isIncomplete = false;
+                    break;
+                case MemberReference:
+                    cs = focus.completeMembers(true);
+                    isIncomplete = false;
+                    break;
+                case Identifier:
+                    cs = focus.completeIdentifiers(ctx.inClass, ctx.inMethod, ctx.partialName);
+                    isIncomplete = cs.size() >= CompileFocus.MAX_COMPLETION_ITEMS;
+                    break;
+                case Annotation:
+                    cs = focus.completeAnnotations(ctx.partialName);
+                    isIncomplete = cs.size() >= CompileFocus.MAX_COMPLETION_ITEMS;
+                    break;
+                case Case:
+                    cs = focus.completeCases();
+                    isIncomplete = false;
+                    break;
+                default:
+                    throw new RuntimeException("Unexpected completion context " + ctx.kind);
+            }
         }
         // Convert to CompletionItem
         var result = new ArrayList<CompletionItem>();
@@ -624,6 +623,7 @@ class JavaLanguageServer extends LanguageServer {
                 || !activeFileCache.file.equals(uri)
                 || activeFileCacheVersion != FileStore.version(uri)) {
             LOG.info("Recompile active file...");
+            if (activeFileCache != null) activeFileCache.close();
             activeFileCache = compiler.compileFile(uri);
             activeFileCacheVersion = FileStore.version(uri);
         }
@@ -744,11 +744,10 @@ class JavaLanguageServer extends LanguageServer {
         if (!FileStore.isJavaFile(uri)) return Optional.empty();
         var line = position.position.line + 1;
         var column = position.position.character + 1;
-        // TODO CompileFocus should have a "patch" mechanism where we recompile the current file without creating a new
-        // task
-        var focus = compiler.compileFocus(uri, line, column);
-        var help = focus.methodInvocation().map(this::asSignatureHelp);
-        return help;
+        try (var focus = compiler.compileFocus(uri, line, column)) {
+            var help = focus.methodInvocation().map(this::asSignatureHelp);
+            return help;
+        }
     }
 
     @Override
@@ -770,26 +769,26 @@ class JavaLanguageServer extends LanguageServer {
         // Compile all files that *might* contain definitions of fromEl
         var toFiles = compiler.potentialDefinitions(toEl.get());
         toFiles.add(fromUri);
-        var batch = compiler.compileBatch(pruneWord(toFiles, toEl.get()));
-
-        // Find fromEl again, so that we have an Element from the current batch
-        var fromElAgain = batch.element(fromUri, fromLine, fromColumn).get();
-
-        // Find all definitions of fromElAgain
-        var toTreePaths = batch.definitions(fromElAgain);
-        if (!toTreePaths.isPresent()) return Optional.empty();
-        var result = new ArrayList<Location>();
-        for (var path : toTreePaths.get()) {
-            var toUri = path.getCompilationUnit().getSourceFile().toUri();
-            var toRange = batch.range(path);
-            if (!toRange.isPresent()) {
-                LOG.warning(String.format("Couldn't locate `%s`", path.getLeaf()));
-                continue;
+        try (var batch = compiler.compileBatch(pruneWord(toFiles, toEl.get()))) {
+            // Find fromEl again, so that we have an Element from the current batch
+            var fromElAgain = batch.element(fromUri, fromLine, fromColumn).get();
+
+            // Find all definitions of fromElAgain
+            var toTreePaths = batch.definitions(fromElAgain);
+            if (!toTreePaths.isPresent()) return Optional.empty();
+            var result = new ArrayList<Location>();
+            for (var path : toTreePaths.get()) {
+                var toUri = path.getCompilationUnit().getSourceFile().toUri();
+                var toRange = batch.range(path);
+                if (!toRange.isPresent()) {
+                    LOG.warning(String.format("Couldn't locate `%s`", path.getLeaf()));
+                    continue;
+                }
+                var from = new Location(toUri, toRange.get());
+                result.add(from);
             }
-            var from = new Location(toUri, toRange.get());
-            result.add(from);
+            return Optional.of(result);
         }
-        return Optional.of(result);
     }
 
     @Override
@@ -811,26 +810,26 @@ class JavaLanguageServer extends LanguageServer {
         // Compile all files that *might* contain references to toEl
         var fromUris = compiler.potentialReferences(toEl.get());
         fromUris.add(toUri);
-        var batch = compiler.compileBatch(pruneWord(fromUris, toEl.get()));
-
-        // Find toEl again, so that we have an Element from the current batch
-        var toElAgain = batch.element(toUri, toLine, toColumn).get();
-
-        // Find all references to toElAgain
-        var fromTreePaths = batch.references(toElAgain);
-        if (!fromTreePaths.isPresent()) return Optional.empty();
-        var result = new ArrayList<Location>();
-        for (var path : fromTreePaths.get()) {
-            var fromUri = path.getCompilationUnit().getSourceFile().toUri();
-            var fromRange = batch.range(path);
-            if (!fromRange.isPresent()) {
-                LOG.warning(String.format("Couldn't locate `%s`", path.getLeaf()));
-                continue;
+        try (var batch = compiler.compileBatch(pruneWord(fromUris, toEl.get()))) {
+            // Find toEl again, so that we have an Element from the current batch
+            var toElAgain = batch.element(toUri, toLine, toColumn).get();
+
+            // Find all references to toElAgain
+            var fromTreePaths = batch.references(toElAgain);
+            if (!fromTreePaths.isPresent()) return Optional.empty();
+            var result = new ArrayList<Location>();
+            for (var path : fromTreePaths.get()) {
+                var fromUri = path.getCompilationUnit().getSourceFile().toUri();
+                var fromRange = batch.range(path);
+                if (!fromRange.isPresent()) {
+                    LOG.warning(String.format("Couldn't locate `%s`", path.getLeaf()));
+                    continue;
+                }
+                var from = new Location(fromUri, fromRange.get());
+                result.add(from);
             }
-            var from = new Location(fromUri, fromRange.get());
-            result.add(from);
+            return Optional.of(result);
         }
-        return Optional.of(result);
     }
 
     private List<JavaFileObject> pruneWord(Collection<URI> files, Element el) {
@@ -1138,18 +1137,18 @@ class JavaLanguageServer extends LanguageServer {
         if (!outOfDate.isEmpty()) {
             // Compile all files that need to be updated in a batch
             outOfDate.add(toUri);
-            var batch = compiler.compileBatch(outOfDate);
-
-            // Find all declarations in toFile
-            var toEls = batch.declarations(toUri);
+            try (var batch = compiler.compileBatch(outOfDate)) {
+                // Find all declarations in toFile
+                var toEls = batch.declarations(toUri);
 
-            // Index outOfDate
-            LOG.info(
-                    String.format(
-                            "...search for references to %d elements in %d files", toEls.size(), outOfDate.size()));
-            for (var fromUri : outOfDate) {
-                var index = batch.index(fromUri, toEls);
-                cacheIndex.put(fromUri, index);
+                // Index outOfDate
+                LOG.info(
+                        String.format(
+                                "...search for references to %d elements in %d files", toEls.size(), outOfDate.size()));
+                for (var fromUri : outOfDate) {
+                    var index = batch.index(fromUri, toEls);
+                    cacheIndex.put(fromUri, index);
+                }
             }
         } else {
             LOG.info("...all indexes are cached and up-to-date");
diff --git a/src/main/java/org/javacs/ParseFile.java b/src/main/java/org/javacs/ParseFile.java
index 33521ed..fe83637 100644
--- a/src/main/java/org/javacs/ParseFile.java
+++ b/src/main/java/org/javacs/ParseFile.java
@@ -5,15 +5,29 @@ import com.sun.source.tree.*;
 import com.sun.source.util.*;
 import java.io.IOException;
 import java.net.URI;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.util.*;
 import java.util.logging.Logger;
 import javax.lang.model.element.*;
+import javax.tools.JavaCompiler;
 import org.javacs.lsp.*;
 
 public class ParseFile {
+    private static final JavaCompiler COMPILER = ServiceLoader.load(JavaCompiler.class).iterator().next();
+
+    /** Create a task that compiles a single file */
+    static JavacTask singleFileTask(JavaCompilerService parent, URI file, String contents) {
+        // TODO could eliminate the connection to parent
+        parent.diags.clear();
+        return (JavacTask)
+                COMPILER.getTask(
+                        null,
+                        parent.fileManager,
+                        parent.diags::add,
+                        JavaCompilerService.options(parent.classPath),
+                        Collections.emptyList(),
+                        List.of(new SourceFileObject(file, contents)));
+    }
+
     private final String contents;
     private final JavacTask task;
     private final Trees trees;
@@ -24,7 +38,7 @@ public class ParseFile {
         Objects.requireNonNull(file);
 
         this.contents = FileStore.contents(file);
-        this.task = CompileFocus.singleFileTask(parent, file, contents);
+        this.task = singleFileTask(parent, file, contents);
         this.trees = Trees.instance(task);
         var profiler = new Profiler();
         task.addTaskListener(profiler);
diff --git a/src/test/java/org/javacs/TaskPool.java b/src/main/java/org/javacs/TaskPool.java
index 8475ae9..8475ae9 100644
--- a/src/test/java/org/javacs/TaskPool.java
+++ b/src/main/java/org/javacs/TaskPool.java
diff --git a/src/test/java/org/javacs/BenchmarkPruner.java b/src/test/java/org/javacs/BenchmarkPruner.java
index a44d687..16c0c4c 100644
--- a/src/test/java/org/javacs/BenchmarkPruner.java
+++ b/src/test/java/org/javacs/BenchmarkPruner.java
@@ -51,12 +51,12 @@ public class BenchmarkPruner {
 
     @Benchmark
     public void pruned(CompilerState state) {
-        state.compiler.compileBatch(List.of(state.pruned));
+        state.compiler.compileBatch(List.of(state.pruned)).close();
     }
 
     @Benchmark
     public void plain(CompilerState state) {
-        state.compiler.compileBatch(List.of(state.file));
+        state.compiler.compileBatch(List.of(state.file)).close();
     }
 
     private static final Logger LOG = Logger.getLogger("main");