Reducing memory leaks in runtime-integration-tests (#10793)

Inspired by the revert done in https://github.com/enso-org/enso/pull/10778, started looking into apparent memory leaks in `runtime-integration-tests`, written in Java.

Initial state:
![Screenshot from 2024-08-09 14-36-29](https://github.com/user-attachments/assets/39abd48f-503b-49d8-af97-da051352c70d)

After:
![Screenshot from 2024-08-12 16-33-40](https://github.com/user-attachments/assets/2bf4cc2d-7e0e-4d22-8810-c2e7e5c3b065)

# Important Notes
Some remaining issues:
- [ ] [TCK tests](https://github.com/enso-org/enso/tree/develop/engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/tck) appear to have some memory leaks but we are essentially enabling them via simple inheritance
- [ ] [RuntimeManagementTest](https://github.com/enso-org/enso/blob/develop/engine/runtime-integration-tests/src/test/scala/org/enso/interpreter/test/semantic/RuntimeManagementTest.scala) appears to be broken as it doesn't seem to shutdown properly created threads:
![Screenshot from 2024-08-12 16-29-09](https://github.com/user-attachments/assets/d90aca62-0562-4287-88b7-6d4719e5cf50)

Leaving this for now, as it will probably need to be taken care by initial authors of those tests, if possible. Plus this PR leaves tests in a much better state than before.

engine/runtime-compiler/src/main/scala/org/enso/compiler/PackageRepository.scala

@@ -105,6 +105,7 @@ trait PackageRepository {
     context: CompilerContext
   ): Option[IRModule]
 
+  def shutdown(): Unit
 }
 
 object PackageRepository {

engine/runtime-integration-tests/src/test/java/org/enso/compiler/ExecStrictCompilerTest.java

@@ -17,8 +17,8 @@ import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.PolyglotException;
 import org.graalvm.polyglot.Source;
 import org.graalvm.polyglot.io.IOAccess;
+import org.junit.After;
 import org.junit.AfterClass;
-import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -45,7 +45,7 @@ public class ExecStrictCompilerTest {
     assertNotNull("Enso language is supported", ctx.getEngine().getLanguages().get("enso"));
   }
 
-  @Before
+  @After
   public void cleanMessages() {
     MESSAGES.reset();
   }
@@ -53,6 +53,7 @@ public class ExecStrictCompilerTest {
   @AfterClass
   public static void closeEnsoContext() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/compiler/ExportedSymbolsTest.java

@@ -47,13 +47,14 @@ public class ExportedSymbolsTest {
         type A_Type
         """);
     ProjectUtils.createProject("Proj", Set.of(mainSrcMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(1));
+      assertThat(mainExportedSymbols.size(), is(1));
-    assertThat(mainExportedSymbols.containsKey("A_Type"), is(true));
+      assertThat(mainExportedSymbols.containsKey("A_Type"), is(true));
-    assertThat(
+      assertThat(
-        mainExportedSymbols.get("A_Type").get(0), instanceOf(BindingsMap.ResolvedType.class));
+          mainExportedSymbols.get("A_Type").get(0), instanceOf(BindingsMap.ResolvedType.class));
+    }
   }
 
   @Test
@@ -70,11 +71,12 @@ public class ExportedSymbolsTest {
         type B_Type
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainSrcMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(2));
+      assertThat(mainExportedSymbols.size(), is(2));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Type", "B_Type"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Type", "B_Type"));
+    }
   }
 
   @Test
@@ -91,11 +93,12 @@ public class ExportedSymbolsTest {
         type B_Type
         """);
     ProjectUtils.createProject("Proj", Set.of(mainMod, bMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(2));
+      assertThat(mainExportedSymbols.size(), is(2));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Type", "B_Type"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Type", "B_Type"));
+    }
   }
 
   @Test
@@ -111,11 +114,12 @@ public class ExportedSymbolsTest {
         export project.A_Module.A_Type as Foo
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainSrcMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(1));
+      assertThat(mainExportedSymbols.size(), is(1));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("Foo"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("Foo"));
+    }
   }
 
   @Test
@@ -133,13 +137,16 @@ public class ExportedSymbolsTest {
         import project.Synthetic_Module
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var syntheticModExpSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Synthetic_Module");
+      var syntheticModExpSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Synthetic_Module");
-    assertThat(
+      assertThat(
-        "Just a A_Module submodule should be exported", syntheticModExpSymbols.size(), is(1));
+          "Just a A_Module submodule should be exported", syntheticModExpSymbols.size(), is(1));
-    assertThat(
+      assertThat(
-        "Just a A_Module submodule should be exported", syntheticModExpSymbols, hasKey("A_Module"));
+          "Just a A_Module submodule should be exported",
+          syntheticModExpSymbols,
+          hasKey("A_Module"));
+    }
   }
 
   @Test
@@ -156,14 +163,16 @@ public class ExportedSymbolsTest {
         export project.A_Module.A_Module
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(1));
+      assertThat(mainExportedSymbols.size(), is(1));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Module"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Module"));
-    assertThat(mainExportedSymbols.get("A_Module").size(), is(1));
+      assertThat(mainExportedSymbols.get("A_Module").size(), is(1));
-    assertThat(
+      assertThat(
-        mainExportedSymbols.get("A_Module").get(0), is(instanceOf(BindingsMap.ResolvedType.class)));
+          mainExportedSymbols.get("A_Module").get(0),
+          is(instanceOf(BindingsMap.ResolvedType.class)));
+    }
   }
 
   @Test
@@ -179,15 +188,16 @@ public class ExportedSymbolsTest {
         export project.A_Module
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(1));
+      assertThat(mainExportedSymbols.size(), is(1));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Module"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("A_Module"));
-    assertThat(mainExportedSymbols.get("A_Module").size(), is(1));
+      assertThat(mainExportedSymbols.get("A_Module").size(), is(1));
-    assertThat(
+      assertThat(
-        mainExportedSymbols.get("A_Module").get(0),
+          mainExportedSymbols.get("A_Module").get(0),
-        is(instanceOf(BindingsMap.ResolvedModule.class)));
+          is(instanceOf(BindingsMap.ResolvedModule.class)));
+    }
   }
 
   @Test
@@ -205,15 +215,16 @@ public class ExportedSymbolsTest {
         export project.Synthetic_Module
         """);
     ProjectUtils.createProject("Proj", Set.of(aMod, mainMod), projDir);
-    var ctx = createCtx(projDir);
+    try (var ctx = createCtx(projDir)) {
-    compile(ctx);
+      compile(ctx);
-    var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
+      var mainExportedSymbols = getExportedSymbolsFromModule(ctx, "local.Proj.Main");
-    assertThat(mainExportedSymbols.size(), is(1));
+      assertThat(mainExportedSymbols.size(), is(1));
-    assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("Synthetic_Module"));
+      assertThat(mainExportedSymbols.keySet(), containsInAnyOrder("Synthetic_Module"));
-    assertThat(mainExportedSymbols.get("Synthetic_Module").size(), is(1));
+      assertThat(mainExportedSymbols.get("Synthetic_Module").size(), is(1));
-    assertThat(
+      assertThat(
-        mainExportedSymbols.get("Synthetic_Module").get(0),
+          mainExportedSymbols.get("Synthetic_Module").get(0),
-        is(instanceOf(BindingsMap.ResolvedModule.class)));
+          is(instanceOf(BindingsMap.ResolvedModule.class)));
+    }
   }
 
   private static Context createCtx(Path projDir) {

engine/runtime-integration-tests/src/test/java/org/enso/compiler/ImportsAndFQNConsistencyTest.java

@@ -103,6 +103,7 @@ main = 42
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   private final Symbol symbol;

engine/runtime-integration-tests/src/test/java/org/enso/compiler/SerdeCompilerTest.java

@@ -74,7 +74,7 @@ public class SerdeCompilerTest {
         var persisted = f.get(10, TimeUnit.SECONDS);
         assertEquals("Fib_Test library has been fully persisted", true, persisted);
       }
-      old = module.getIr();
+      old = module.getIr().duplicate(true, true, true, false);
       ctx.leave();
     }
 
@@ -103,7 +103,7 @@ public class SerdeCompilerTest {
       var mainValue = ctx.asValue(main);
       assertEquals(42, mainValue.execute().asInt());
 
-      now = module.getIr();
+      now = module.getIr().duplicate(true, true, true, false);
 
       ctx.leave();
     }

engine/runtime-integration-tests/src/test/java/org/enso/compiler/SerializationManagerTest.java

@@ -28,11 +28,12 @@ public class SerializationManagerTest {
 
   private static final long COMPILE_TIMEOUT_SECONDS = 20;
 
-  private final PackageManager<TruffleFile> packageManager;
+  private PackageManager<TruffleFile> packageManager;
-  private final InterpreterContext interpreterContext;
+  private InterpreterContext interpreterContext;
-  private final EnsoContext ensoContext;
+  private EnsoContext ensoContext;
 
-  public SerializationManagerTest() {
+  @Before
+  public void setup() {
     packageManager = new PackageManager<>(new TruffleFileSystem());
     interpreterContext = new InterpreterContext(x -> x);
     ensoContext =
@@ -41,22 +42,20 @@ public class SerializationManagerTest {
             .getBindings(LanguageInfo.ID)
             .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
             .asHostObject();
-  }
-
-  @Before
-  public void setup() {
     interpreterContext.ctx().initialize(LanguageInfo.ID);
     interpreterContext.ctx().enter();
   }
 
   @After
   public void teardown() {
-    interpreterContext.ctx().close();
+    interpreterContext.close();
+    ensoContext.shutdown();
+    ensoContext = null;
   }
 
   private Path getLibraryPath(LibraryName libraryName) {
     return Paths.get(
-            interpreterContext.languageHome(),
+            interpreterContext.languageHome().toFile().getAbsolutePath(),
             "..",
             "lib",
             libraryName.namespace(),

engine/runtime-integration-tests/src/test/java/org/enso/compiler/SerializerTest.java

@@ -42,29 +42,29 @@ public class SerializerTest {
     var pkgPath = new File(getClass().getClassLoader().getResource(testName).getPath());
     var pkg = PackageManager.Default().fromDirectory(pkgPath).get();
 
-    var ctx = ensoContextForPackage(testName, pkgPath);
+    try (var ctx = ensoContextForPackage(testName, pkgPath)) {
-    var ensoContext =
+      var ensoContext =
-        (EnsoContext)
+          (EnsoContext)
-            ctx.getBindings(LanguageInfo.ID)
+              ctx.getBindings(LanguageInfo.ID)
-                .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
+                  .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
-                .asHostObject();
+                  .asHostObject();
-    var mainModuleOpt = ensoContext.getModuleForFile(pkg.mainFile());
+      var mainModuleOpt = ensoContext.getModuleForFile(pkg.mainFile());
-    assertEquals(mainModuleOpt.isPresent(), true);
+      assertEquals(mainModuleOpt.isPresent(), true);
 
-    var compiler = ensoContext.getCompiler();
+      var compiler = ensoContext.getCompiler();
-    var module = mainModuleOpt.get().asCompilerModule();
+      var module = mainModuleOpt.get().asCompilerModule();
 
-    ctx.enter();
+      ctx.enter();
-    var result = compiler.run(module);
+      var result = compiler.run(module);
-    assertEquals(result.compiledModules().exists(m -> m == module), true);
+      assertEquals(result.compiledModules().exists(m -> m == module), true);
-    var useThreadPool = compiler.context().isCreateThreadAllowed();
+      var useThreadPool = compiler.context().isCreateThreadAllowed();
-    var future = compiler.context().serializeModule(compiler, module, true, useThreadPool);
+      var future = compiler.context().serializeModule(compiler, module, true, useThreadPool);
-    var serialized = future.get(5, TimeUnit.SECONDS);
+      var serialized = future.get(5, TimeUnit.SECONDS);
-    assertEquals(serialized, true);
+      assertEquals(serialized, true);
-    var deserialized = compiler.context().deserializeModule(compiler, module);
+      var deserialized = compiler.context().deserializeModule(compiler, module);
-    assertTrue("Deserialized", deserialized);
+      assertTrue("Deserialized", deserialized);
-    compiler.context().shutdown(true);
+      compiler.context().shutdown(true);
-    ctx.leave();
+      ctx.leave();
-    ctx.close();
+    }
   }
 }

engine/runtime-integration-tests/src/test/java/org/enso/compiler/VectorArraySignatureTest.java

@@ -35,6 +35,7 @@ public class VectorArraySignatureTest {
   @AfterClass
   public static void closeEnsoParser() throws Exception {
     ensoCompiler.close();
+    ensoCompiler = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/compiler/dump/test/IRDumpTest.java

@@ -19,8 +19,7 @@ public class IRDumpTest {
     System.setProperty(IRDumper.SYSTEM_PROP, "true");
     try (var ctx = ContextUtils.defaultContextBuilder().out(out).build()) {
       // Dumping is done in the compiler, so it is enough just to compile the module
-      var moduleIr =
+      ContextUtils.compileModule(ctx, """
-          ContextUtils.compileModule(ctx, """
           main = 42
           """, "MyMainModule");
       assertThat(
@@ -39,6 +38,7 @@ public class IRDumpTest {
       } catch (IOException e) {
         // Ignore. The ir-dumps directory should be deleted eventually.
       }
+      out.reset();
     }
   }
 }

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/caches/ModuleCacheTest.java

@@ -14,6 +14,7 @@ import org.enso.interpreter.runtime.EnsoContext;
 import org.enso.test.utils.ContextUtils;
 import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.Source;
+import org.junit.AfterClass;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -30,6 +31,12 @@ public class ModuleCacheTest {
             .build();
   }
 
+  @AfterClass
+  public static void disposeContext() {
+    ctx.close();
+    ctx = null;
+  }
+
   @Test
   public void testCompareList() throws Exception {
     var ensoCtx =

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/node/callable/PolyglotCallTypeTest.java

@@ -27,6 +27,7 @@ public class PolyglotCallTypeTest {
   @AfterClass
   public static void closeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/node/expression/builtin/meta/TypeOfNodeTest.java

@@ -66,6 +66,7 @@ public class TypeOfNodeTest {
   public static void disposeCtx() throws Exception {
     if (ctx != null) {
       ctx.close();
+      ctx = null;
     }
   }
 

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/runtime/ModuleSourcesTest.java

@@ -42,6 +42,7 @@ public class ModuleSourcesTest {
   public void cleanup() {
     f.delete();
     this.ctx.close();
+    this.ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/runtime/ModuleTest.java

@@ -50,6 +50,7 @@ public class ModuleTest {
   public void cleanup() {
     f.delete();
     this.ctx.close();
+    this.ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/AtomConstructorTest.java

@@ -31,6 +31,7 @@ public class AtomConstructorTest {
   @AfterClass
   public static void closeContext() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/AtomInteropTest.java

@@ -27,6 +27,7 @@ public class AtomInteropTest {
   @After
   public void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/AutoscopedConstructorTest.java

@@ -12,8 +12,8 @@ import org.enso.common.MethodNames;
 import org.enso.test.utils.ContextUtils;
 import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.PolyglotException;
+import org.junit.After;
 import org.junit.AfterClass;
-import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -28,7 +28,7 @@ public class AutoscopedConstructorTest {
     ctx = ContextUtils.createDefaultContext(out);
   }
 
-  @Before
+  @After
   public void resetOut() {
     out.reset();
   }
@@ -36,6 +36,7 @@ public class AutoscopedConstructorTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/BigNumberTest.java

@@ -28,6 +28,7 @@ public class BigNumberTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/BinaryDispatchTest.java

@@ -63,7 +63,9 @@ public class BinaryDispatchTest {
 
   @AfterClass
   public static void closeCtx() {
+    module = null;
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/BinaryOpFloatTest.java

@@ -89,6 +89,7 @@ public class BinaryOpFloatTest {
   @AfterClass
   public static void closeContext() {
     ctx.close();
+    ctx = null;
   }
 
   private final String operation;

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/BinaryOpIntegerTest.java

@@ -108,6 +108,7 @@ public class BinaryOpIntegerTest {
   @AfterClass
   public static void closeContext() {
     ctx.close();
+    ctx = null;
   }
 
   private final String operation;

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/ContextTest.java

@@ -0,0 +1,27 @@
+package org.enso.interpreter.test;
+
+import java.io.OutputStream;
+import org.enso.test.utils.ContextUtils;
+import org.graalvm.polyglot.Context;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+
+public class ContextTest {
+
+  protected static Context ctx;
+
+  @BeforeClass
+  public static void prepareCtx() {
+    ctx =
+        ContextUtils.defaultContextBuilder()
+            .out(OutputStream.nullOutputStream())
+            .err(OutputStream.nullOutputStream())
+            .build();
+  }
+
+  @AfterClass
+  public static void disposeCtx() {
+    ctx.close();
+    ctx = null;
+  }
+}

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/ConversionMethodTests.java

@@ -10,8 +10,8 @@ import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.Value;
 import org.hamcrest.MatcherAssert;
 import org.hamcrest.Matchers;
+import org.junit.After;
 import org.junit.AfterClass;
-import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -28,9 +28,10 @@ public class ConversionMethodTests {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
-  @Before
+  @After
   public void resetOutput() {
     out.reset();
   }

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/DebuggingEnsoTest.java

@@ -79,7 +79,9 @@ public class DebuggingEnsoTest {
   @After
   public void disposeContext() {
     context.close();
+    context = null;
     engine.close();
+    engine = null;
   }
 
   private static void expectStackFrame(

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/DiagnosticFormatterTest.java

@@ -55,6 +55,7 @@ public class DiagnosticFormatterTest {
   @After
   public void closeCtx() throws IOException {
     ctx.close();
+    ctx = null;
     output.close();
   }
 

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/EqualsConversionsTest.java

@@ -23,6 +23,7 @@ public class EqualsConversionsTest {
   @AfterClass
   public static void disposeContext() {
     context.close();
+    context = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/EqualsTest.java

@@ -61,6 +61,8 @@ public class EqualsTest {
   @AfterClass
   public static void disposeContext() {
     context.close();
+    context = null;
+    unwrappedValues = null;
   }
 
   @DataPoints public static Object[] unwrappedValues;
@@ -90,6 +92,8 @@ public class EqualsTest {
           .toArray(new Object[] {});
     } catch (Exception e) {
       throw new AssertionError(e);
+    } finally {
+      valGenerator.dispose();
     }
   }
 

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/FindExceptionMessageTest.java

@@ -29,6 +29,7 @@ public class FindExceptionMessageTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/ForeignMethodInvokeTest.java

@@ -27,6 +27,7 @@ public class ForeignMethodInvokeTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/HashCodeTest.java

@@ -53,6 +53,8 @@ public class HashCodeTest {
   @AfterClass
   public static void disposeContext() {
     context.close();
+    context = null;
+    unwrappedValues = null;
   }
 
   /**

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/InsightForEnsoTest.java

@@ -60,7 +60,9 @@ public class InsightForEnsoTest {
   @After
   public void disposeContext() throws Exception {
     this.insightHandle.close();
+    this.out.reset();
     this.ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/IntegerTest.java

@@ -40,6 +40,7 @@ public class IntegerTest {
   @AfterClass
   public static void teardown() {
     ctx.close();
+    ctx = null;
   }
 
   private static final EnsoBigInteger bigInt =

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/JavaInteropTest.java

@@ -12,8 +12,8 @@ import org.enso.test.utils.ContextUtils;
 import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.PolyglotException;
 import org.graalvm.polyglot.Value;
+import org.junit.After;
 import org.junit.AfterClass;
-import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -30,9 +30,10 @@ public class JavaInteropTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
-  @Before
+  @After
   public void resetOutput() {
     out.reset();
   }

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/JsInteropTest.java

@@ -18,12 +18,13 @@ public class JsInteropTest {
   @Before
   public void initContext() {
     ctx = ContextUtils.createDefaultContext(out);
-    out.reset();
   }
 
   @After
   public void disposeCtx() {
     ctx.close();
+    ctx = null;
+    out.reset();
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/ListTest.java

@@ -64,7 +64,15 @@ public class ListTest {
 
   @After
   public void disposeCtx() {
+    generator = null;
+    plusOne = null;
+    evenOnes = null;
+    taken = null;
+    init = null;
+    asVector = null;
+    asText = null;
     this.ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/MetaIsATest.java

@@ -53,7 +53,10 @@ public class MetaIsATest {
       generator.dispose();
       generator = null;
     }
+    isACheck = null;
+    warningCheck = null;
     ctx.close();
+    ctx = null;
   }
 
   /**

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/NonStrictModeTests.java

@@ -38,6 +38,7 @@ public class NonStrictModeTests {
   @AfterClass
   public static void disposeCtx() {
     nonStrictCtx.close();
+    nonStrictCtx = null;
   }
 
   @Before

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/PolyglotErrorTest.java

@@ -93,7 +93,9 @@ public class PolyglotErrorTest {
 
   @After
   public void disposeCtx() {
+    this.panic = null;
     this.ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/RootNamesTest.java

@@ -55,6 +55,8 @@ public class RootNamesTest {
   public void disposeContext() throws Exception {
     this.insightHandle.close();
     this.ctx.close();
+    this.ctx = null;
+    this.out.reset();
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/SignatureTest.java

@@ -6,36 +6,16 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
-import java.io.OutputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
 import org.enso.common.MethodNames;
-import org.enso.test.utils.ContextUtils;
-import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.PolyglotException;
 import org.graalvm.polyglot.Source;
 import org.graalvm.polyglot.Value;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
 import org.junit.Test;
 
-public class SignatureTest {
+public class SignatureTest extends ContextTest {
-  private static Context ctx;
-
-  @BeforeClass
-  public static void prepareCtx() {
-    ctx =
-        ContextUtils.defaultContextBuilder()
-            .out(OutputStream.nullOutputStream())
-            .err(OutputStream.nullOutputStream())
-            .build();
-  }
-
-  @AfterClass
-  public static void disposeCtx() {
-    ctx.close();
-  }
 
   @Test
   public void wrongFunctionSignature() throws Exception {

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/SymbolResolutionTest.java

@@ -3,32 +3,12 @@ package org.enso.interpreter.test;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
-import java.io.OutputStream;
 import java.net.URI;
 import org.enso.common.MethodNames;
-import org.enso.test.utils.ContextUtils;
-import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.Source;
-import org.junit.AfterClass;
-import org.junit.BeforeClass;
 import org.junit.Test;
 
-public class SymbolResolutionTest {
+public class SymbolResolutionTest extends ContextTest {
-  private static Context ctx;
-
-  @BeforeClass
-  public static void prepareCtx() {
-    ctx =
-        ContextUtils.defaultContextBuilder()
-            .out(OutputStream.nullOutputStream())
-            .err(OutputStream.nullOutputStream())
-            .build();
-  }
-
-  @AfterClass
-  public static void disposeCtx() {
-    ctx.close();
-  }
 
   @Test
   public void resolvingLocalSymbol() throws Exception {

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/TypeInferenceConsistencyTest.java

@@ -10,8 +10,8 @@ import org.enso.test.utils.ContextUtils;
 import org.graalvm.polyglot.Context;
 import org.graalvm.polyglot.PolyglotException;
 import org.graalvm.polyglot.Source;
+import org.junit.After;
 import org.junit.AfterClass;
-import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -34,7 +34,7 @@ public class TypeInferenceConsistencyTest {
             .build();
   }
 
-  @Before
+  @After
   public void cleanMessages() {
     output.reset();
   }
@@ -46,6 +46,7 @@ public class TypeInferenceConsistencyTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/TypeMembersTest.java

@@ -28,6 +28,7 @@ public class TypeMembersTest {
   @After
   public void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/VectorSortTest.java

@@ -47,12 +47,14 @@ public class VectorSortTest {
     values.addAll(valuesGenerator.booleans());
     values.addAll(valuesGenerator.durations());
     values.addAll(valuesGenerator.maps());
+    valuesGenerator.dispose();
   }
 
   @AfterClass
   public static void disposeCtx() {
     values.clear();
     context.close();
+    context = null;
   }
 
   @DataPoints public static List<Value> values;

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/VectorTest.java

@@ -27,6 +27,7 @@ public class VectorTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close();
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/WarningsTest.java

@@ -48,8 +48,11 @@ public class WarningsTest {
 
   @AfterClass
   public static void disposeContext() {
-    ensoContext = null;
+    generator.dispose();
     ctx.close();
+    ctx = null;
+    ensoContext.shutdown();
+    ensoContext = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/asserts/AssertionsTest.java

@@ -42,6 +42,7 @@ public class AssertionsTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close(true);
+    ctx = null;
   }
 
   @After

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/asserts/DisabledAssertionsTest.java

@@ -27,6 +27,7 @@ public class DisabledAssertionsTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close(true);
+    ctx = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/asserts/SuccessfulAssertionExpressionTest.java

@@ -36,6 +36,7 @@ public class SuccessfulAssertionExpressionTest {
   @AfterClass
   public static void disposeCtx() {
     ctx.close(true);
+    ctx = null;
   }
 
   @After

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/instrument/AvoidIdInstrumentationTagTest.java

@@ -44,7 +44,9 @@ public class AvoidIdInstrumentationTagTest {
 
   @After
   public void disposeContext() {
+    nodes = null;
     context.close();
+    context = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/instrument/FunctionPointerTest.java

@@ -48,6 +48,7 @@ public class FunctionPointerTest {
   @After
   public void disposeContext() {
     context.close();
+    context = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/instrument/IncrementalUpdatesTest.java

@@ -68,7 +68,9 @@ public class IncrementalUpdatesTest {
 
   @After
   public void teardownContext() {
+    nodeCountingInstrument = null;
     context.close();
+    context = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/java/org/enso/interpreter/test/instrument/WarningInstrumentationTest.java

@@ -62,7 +62,9 @@ public class WarningInstrumentationTest {
 
   @After
   public void disposeContext() {
+    instrument = null;
     context.close();
+    context = null;
   }
 
   @Test

engine/runtime-integration-tests/src/test/scala/org/enso/compiler/refactoring/IRUtilsTest.scala

@@ -16,7 +16,8 @@ import java.util.UUID
 
 class IRUtilsTest extends AnyWordSpecLike with Matchers with OptionValues {
   private val ctx = new InterpreterContext()
-  private val langCtx = ctx.ctx
+  private val langCtx = ctx
+    .ctx()
     .getBindings(LanguageInfo.ID)
     .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
     .asHostObject[EnsoContext]()

engine/runtime-integration-tests/src/test/scala/org/enso/compiler/test/ModifiedTest.scala

@@ -71,13 +71,15 @@ trait ModifiedTest
       .build()
     context.initialize(LanguageInfo.ID)
     val executionContext = new PolyglotContext(context)
-    InterpreterException.rethrowPolyglot {
+    val result = InterpreterException.rethrowPolyglot {
       val topScope        = executionContext.getTopScope
       val mainModuleScope = topScope.getModule(mainModule.toString)
       val assocCons       = mainModuleScope.getAssociatedType
       val mainFun         = mainModuleScope.getMethod(assocCons, "main").get
       mainFun.execute()
     }
+    context.close()
+    result
   }
 
   private def initialCopy(from: File, to: File): Unit = {

engine/runtime-integration-tests/src/test/scala/org/enso/compiler/test/context/SuggestionBuilderTest.scala

@@ -16,7 +16,8 @@ import java.util.UUID
 
 class SuggestionBuilderTest extends AnyWordSpecLike with Matchers {
   private val ctx = new InterpreterContext()
-  private val langCtx = ctx.ctx
+  private val langCtx = ctx
+    .ctx()
     .getBindings(LanguageInfo.ID)
     .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
     .asHostObject[EnsoContext]()

engine/runtime-integration-tests/src/test/scala/org/enso/compiler/test/semantic/TypeSignaturesTest.scala

@@ -130,7 +130,8 @@ class TypeSignaturesTest
     with TypeMatchers {
 
   private val ctx = new InterpreterContext()
-  private val langCtx = ctx.ctx
+  private val langCtx = ctx
+    .ctx()
     .getBindings(LanguageInfo.ID)
     .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
     .asHostObject[EnsoContext]()

engine/runtime-integration-tests/src/test/scala/org/enso/interpreter/test/InterpreterTest.scala

@@ -15,7 +15,6 @@ import org.enso.polyglot.debugger.{
 }
 import org.enso.common.LanguageInfo
 import org.enso.common.RuntimeOptions
-
 import org.enso.polyglot.{Function, PolyglotContext}
 import org.graalvm.polyglot.{Context, Value}
 import org.scalatest.Assertions
@@ -28,7 +27,7 @@ import java.io.{
   PipedOutputStream,
   PrintStream
 }
-import java.nio.file.Paths
+import java.nio.file.{Path, Paths}
 import java.util.UUID
 import java.util.logging.Level
 
@@ -104,43 +103,101 @@ class ReplaceableSessionManager extends SessionManager {
 class InterpreterContext(
   contextModifiers: Context#Builder => Context#Builder = bldr => bldr
 ) {
-  val output         = new ByteArrayOutputStream()
+  var _ctx: Context                              = _
-  val err            = new ByteArrayOutputStream()
+  var _err: ByteArrayOutputStream                = _
-  val inOut          = new PipedOutputStream()
+  var _output: ByteArrayOutputStream             = new ByteArrayOutputStream()
-  val inOutPrinter   = new PrintStream(inOut, true)
+  var _in: PipedInputStream                      = _
-  val in             = new PipedInputStream(inOut)
+  var _inOut: PipedOutputStream                  = _
-  val sessionManager = new ReplaceableSessionManager
+  var _inOutPrinter: PrintStream                 = _
+  var _sessionManager: ReplaceableSessionManager = new ReplaceableSessionManager
+  var _languageHome: Path                        = _
+  val edition                                    = "0.0.0-dev"
+  def ctx(): Context = {
+    if (_ctx == null) {
+      _output       = new ByteArrayOutputStream()
+      _err          = new ByteArrayOutputStream()
+      _inOut        = new PipedOutputStream()
+      _inOutPrinter = new PrintStream(_inOut, true)
+      _in           = new PipedInputStream(_inOut)
 
-  val languageHome = Paths
+      _languageHome = Paths
-    .get("../../test/micro-distribution/component")
+        .get("../../test/micro-distribution/component")
-    .toFile
-    .getAbsolutePath
-  val edition = "0.0.0-dev"
 
-  val ctx = contextModifiers(
+      _ctx = contextModifiers(
-    Context
+        Context
-      .newBuilder(LanguageInfo.ID)
+          .newBuilder(LanguageInfo.ID)
-      .allowExperimentalOptions(true)
+          .allowExperimentalOptions(true)
-      .allowAllAccess(true)
+          .allowAllAccess(true)
-      .allowCreateThread(false)
+          .allowCreateThread(false)
-      .out(output)
+          .out(_output)
-      .err(err)
+          .err(_err)
-      .option(RuntimeOptions.LOG_LEVEL, Level.WARNING.getName())
+          .option(RuntimeOptions.LOG_LEVEL, Level.WARNING.getName())
-      .option(RuntimeOptions.DISABLE_IR_CACHES, "true")
+          .option(RuntimeOptions.DISABLE_IR_CACHES, "true")
-      .option(RuntimeOptions.STRICT_ERRORS, "false")
+          .option(RuntimeOptions.STRICT_ERRORS, "false")
-      .environment("NO_COLOR", "true")
+          .environment("NO_COLOR", "true")
-      .logHandler(System.err)
+          .logHandler(System.err)
-      .in(in)
+          .in(_in)
-      .option(RuntimeOptions.LANGUAGE_HOME_OVERRIDE, languageHome)
+          .option(
-      .option(RuntimeOptions.EDITION_OVERRIDE, edition)
+            RuntimeOptions.LANGUAGE_HOME_OVERRIDE,
-      .option("engine.WarnInterpreterOnly", "false")
+            _languageHome.toFile.getAbsolutePath
-      .serverTransport { (uri, peer) =>
+          )
-        if (uri.toString == DebugServerInfo.URI) {
+          .option(RuntimeOptions.EDITION_OVERRIDE, edition)
-          new DebuggerSessionManagerEndpoint(sessionManager, peer)
+          .option("engine.WarnInterpreterOnly", "false")
-        } else null
+          .serverTransport { (uri, peer) =>
-      }
+            if (uri.toString == DebugServerInfo.URI) {
-  ).build()
+              new DebuggerSessionManagerEndpoint(_sessionManager, peer)
-  lazy val executionContext = new PolyglotContext(ctx)
+            } else null
+          }
+      ).build()
+    }
+    _ctx
+  }
+
+  def err(): ByteArrayOutputStream = {
+    assert(_ctx != null)
+    _err
+  }
+
+  def output(): ByteArrayOutputStream = {
+    _output
+  }
+
+  def in(): PipedInputStream = {
+    assert(_ctx != null)
+    _in
+  }
+
+  def inOut(): PipedOutputStream = {
+    assert(_ctx != null)
+    _inOut;
+  }
+
+  def inOutPrinter(): PrintStream = {
+    assert(_ctx != null)
+    _inOutPrinter
+  }
+
+  def sessionManager(): ReplaceableSessionManager = {
+    _sessionManager
+  }
+
+  def languageHome(): Path = {
+    assert(_ctx != null)
+    _languageHome
+  }
+
+  def close(): Unit = {
+    if (_ctx != null) {
+      _ctx.close()
+      _ctx = null
+    }
+
+    _output.reset()
+    if (_err != null) _err.close()
+    if (_in != null) _in.close()
+    if (_inOut != null) _inOut.close()
+  }
+  lazy val executionContext = new PolyglotContext(ctx())
 }
 
 trait InterpreterRunner {
@@ -154,7 +211,10 @@ trait InterpreterRunner {
   def withLocationsInstrumenter(
     test: LocationsInstrumenter => Unit
   )(implicit interpreterContext: InterpreterContext): Unit = {
-    val instrument = interpreterContext.ctx.getEngine.getInstruments
+    val instrument = interpreterContext
+      .ctx()
+      .getEngine
+      .getInstruments
       .get(CodeLocationsTestInstrument.INSTRUMENT_ID)
       .lookup(classOf[CodeLocationsTestInstrument])
     val instrumenter = LocationsInstrumenter(instrument)
@@ -166,7 +226,10 @@ trait InterpreterRunner {
   def withIdsInstrumenter(
     test: IdsInstrumenter => Unit
   )(implicit interpreterContext: InterpreterContext): Unit = {
-    val instrument = interpreterContext.ctx.getEngine.getInstruments
+    val instrument = interpreterContext
+      .ctx()
+      .getEngine
+      .getInstruments
       .get(CodeIdsTestInstrument.INSTRUMENT_ID)
       .lookup(classOf[CodeIdsTestInstrument])
     val instrumenter = IdsInstrumenter(instrument)
@@ -185,7 +248,7 @@ trait InterpreterRunner {
   def getMain(
     code: String
   )(implicit interpreterContext: InterpreterContext): MainMethod = {
-    interpreterContext.output.reset()
+    interpreterContext.output().reset()
     val module = InterpreterException.rethrowPolyglot(
       interpreterContext.executionContext.evalModule(code, "Test")
     )
@@ -206,52 +269,52 @@ trait InterpreterRunner {
   def consumeErr(implicit
     interpreterContext: InterpreterContext
   ): List[String] = {
-    val result = interpreterContext.err.toString
+    val result = interpreterContext.err().toString
-    interpreterContext.err.reset()
+    interpreterContext.err().reset()
     result.linesIterator.toList
   }
 
   def consumeErrBytes(implicit
     interpreterContext: InterpreterContext
   ): Array[Byte] = {
-    val result = interpreterContext.err.toByteArray
+    val result = interpreterContext.err().toByteArray
-    interpreterContext.err.reset()
+    interpreterContext.err().reset()
     result
   }
 
   def consumeOut(implicit
     interpreterContext: InterpreterContext
   ): List[String] = {
-    val result = interpreterContext.output.toString
+    val result = interpreterContext.output().toString
-    interpreterContext.output.reset()
+    interpreterContext.output().reset()
     result.linesIterator.toList
   }
 
   def consumeOutBytes(implicit
     interpreterContext: InterpreterContext
   ): Array[Byte] = {
-    val result = interpreterContext.output.toByteArray
+    val result = interpreterContext.output().toByteArray
-    interpreterContext.output.reset()
+    interpreterContext.output().reset()
     result
   }
 
   def feedInput(
     string: String
   )(implicit interpreterContext: InterpreterContext): Unit = {
-    interpreterContext.inOutPrinter.println(string)
+    interpreterContext.inOutPrinter().println(string)
   }
 
   def feedBytes(
     input: Array[Byte]
   )(implicit interpreterContext: InterpreterContext): Unit = {
-    interpreterContext.inOut.write(input)
+    interpreterContext.inOut().write(input)
-    interpreterContext.inOut.flush()
+    interpreterContext.inOut().flush()
   }
 
   def setSessionManager(
     manager: SessionManager
   )(implicit interpreterContext: InterpreterContext): Unit =
-    interpreterContext.sessionManager.setSessionManager(manager)
+    interpreterContext.sessionManager().setSessionManager(manager)
 
   // For Enso raw text blocks inside scala multiline strings
   val rawTQ = "\"\"\""

engine/runtime-integration-tests/src/test/scala/org/enso/interpreter/test/instrument/RuntimeServerTest.scala

@@ -36,7 +36,7 @@ class RuntimeServerTest
 
     val out: ByteArrayOutputStream    = new ByteArrayOutputStream()
     val logOut: ByteArrayOutputStream = new ByteArrayOutputStream()
-    val context =
+    protected val context =
       Context
         .newBuilder(LanguageInfo.ID)
         .allowExperimentalOptions(true)

engine/runtime-integration-tests/src/test/scala/org/enso/interpreter/test/semantic/RuntimeManagementTest.scala

@@ -15,7 +15,8 @@ class RuntimeManagementTest extends InterpreterTest {
   ): Unit = {
 
     "Interrupt threads through Thread#interrupt()" in {
-      val langCtx = interpreterContext.ctx
+      val langCtx = interpreterContext
+        .ctx()
         .getBindings(LanguageInfo.ID)
         .invokeMember(MethodNames.TopScope.LEAK_CONTEXT)
         .asHostObject[EnsoContext]()

engine/runtime/src/main/java/org/enso/interpreter/runtime/EnsoContext.java

@@ -290,6 +290,10 @@ public final class EnsoContext {
     threadManager.shutdown();
     resourceManager.shutdown();
     compiler.shutdown(shouldWaitForPendingSerializationJobs);
+    packageRepository.shutdown();
+    guestJava = null;
+    topScope = null;
+    hostClassLoader.close();
   }
 
   private boolean shouldAssertionsBeEnabled() {

engine/runtime/src/main/java/org/enso/interpreter/runtime/HostClassLoader.java

@@ -17,7 +17,7 @@ import org.slf4j.LoggerFactory;
  * the classes that are loaded via this class loader are first searched inside those archives. If
  * not found, delegates to parent class loaders.
  */
-final class HostClassLoader extends URLClassLoader {
+final class HostClassLoader extends URLClassLoader implements AutoCloseable {
 
   private final Map<String, Class<?>> loadedClasses = new ConcurrentHashMap<>();
   private static final Logger logger = LoggerFactory.getLogger(HostClassLoader.class);
@@ -84,4 +84,9 @@ final class HostClassLoader extends URLClassLoader {
       return super.findResources(name);
     }
   }
+
+  @Override
+  public void close() {
+    loadedClasses.clear();
+  }
 }

engine/runtime/src/main/java/org/enso/interpreter/runtime/SerializationPool.java

@@ -121,6 +121,7 @@ final class SerializationPool {
         t.join();
       }
       context.logSerializationManager(Level.FINE, "Serialization manager has been shut down.");
+      threads.clear();
     }
   }
 

engine/runtime/src/main/scala/org/enso/interpreter/runtime/DefaultPackageRepository.scala

@@ -610,6 +610,13 @@ private class DefaultPackageRepository(
       }
     else Failure(PackageManager.PackageNotFound())
   }
+
+  override def shutdown(): Unit = {
+    loadedPackages.clear()
+    loadedModules.clear()
+    loadedComponents.clear()
+    loadedLibraryBindings.clear()
+  }
 }
 
 private object DefaultPackageRepository {