8210094: Better loading of classloader classes

Reviewed-by: acorn, hseigel, ahgross, rhalade

src/share/vm/classfile/classFileParser.cpp

@@ -4210,9 +4210,6 @@ instanceKlassHandle ClassFileParser::parseClassFile(Symbol* name,
           this_klass(), &all_mirandas, CHECK_(nullHandle));
     }
 
-    // Update the loader_data graph.
-    record_defined_class_dependencies(this_klass, CHECK_NULL);
-
     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(this_klass()),
                                              false /* not shared class */);
 
@@ -4498,30 +4495,6 @@ void ClassFileParser::set_precomputed_flags(instanceKlassHandle k) {
   }
 }
 
-// Attach super classes and interface classes to class loader data
-void ClassFileParser::record_defined_class_dependencies(instanceKlassHandle defined_klass, TRAPS) {
-  ClassLoaderData * defining_loader_data = defined_klass->class_loader_data();
-  if (defining_loader_data->is_the_null_class_loader_data()) {
-      // Dependencies to null class loader data are implicit.
-      return;
-  } else {
-    // add super class dependency
-    Klass* super = defined_klass->super();
-    if (super != NULL) {
-      defining_loader_data->record_dependency(super, CHECK);
-    }
-
-    // add super interface dependencies
-    Array<Klass*>* local_interfaces = defined_klass->local_interfaces();
-    if (local_interfaces != NULL) {
-      int length = local_interfaces->length();
-      for (int i = 0; i < length; i++) {
-        defining_loader_data->record_dependency(local_interfaces->at(i), CHECK);
-      }
-    }
-  }
-}
-
 // utility methods for appending an array with check for duplicates
 
 void append_interfaces(GrowableArray<Klass*>* result, Array<Klass*>* ifs) {

src/share/vm/classfile/dictionary.cpp

 /*
- * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -159,33 +159,9 @@ void Dictionary::do_unloading() {
       if (!is_strongly_reachable(loader_data, e)) {
         // Entry was not visited in phase1 (negated test from phase1)
         assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
-        ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
-
-        // Do we need to delete this system dictionary entry?
-        bool purge_entry = false;
 
         // Do we need to delete this system dictionary entry?
         if (loader_data->is_unloading()) {
-          // If the loader is not live this entry should always be
-          // removed (will never be looked up again).
-          purge_entry = true;
-        } else {
-          // The loader in this entry is alive. If the klass is dead,
-          // (determined by checking the defining class loader)
-          // the loader must be an initiating loader (rather than the
-          // defining loader). Remove this entry.
-          if (k_def_class_loader_data->is_unloading()) {
-            // If we get here, the class_loader_data must not be the defining
-            // loader, it must be an initiating one.
-            assert(k_def_class_loader_data != loader_data,
-                   "cannot have live defining loader and unreachable klass");
-            // Loader is live, but class and its defining loader are dead.
-            // Remove the entry. The class is going away.
-            purge_entry = true;
-          }
-        }
-
-        if (purge_entry) {
           *p = probe->next();
           if (probe == _current_class_entry) {
             _current_class_entry = NULL;

src/share/vm/classfile/systemDictionary.cpp

@@ -816,7 +816,16 @@ Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
 
         // Need to check for a PENDING_EXCEPTION again; check_constraints
-        // can throw and doesn't use the CHECK macro.
+        // can throw but we may have to remove entry from the placeholder table below.
+        if (!HAS_PENDING_EXCEPTION) {
+          // Record dependency for non-parent delegation.
+          // This recording keeps the defining class loader of the klass (k) found
+          // from being unloaded while the initiating class loader is loaded
+          // even if the reference to the defining class loader is dropped
+          // before references to the initiating class loader.
+          loader_data->record_dependency(k(), THREAD);
+        }
+
         if (!HAS_PENDING_EXCEPTION) {
           { // Grabbing the Compile_lock prevents systemDictionary updates
             // during compilations.

src/share/vm/classfile/verificationType.cpp

 /*
- * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -63,7 +63,6 @@ bool VerificationType::is_reference_assignable_from(
         name(), Handle(THREAD, klass->class_loader()),
         Handle(THREAD, klass->protection_domain()), true, CHECK_false);
     KlassHandle this_class(THREAD, obj);
-    klass->class_loader_data()->record_dependency(obj, CHECK_false);
 
     if (this_class->is_interface() && (!from_field_is_protected ||
         from.name() != vmSymbols::java_lang_Object())) {
@@ -75,7 +74,6 @@ bool VerificationType::is_reference_assignable_from(
       Klass* from_class = SystemDictionary::resolve_or_fail(
           from.name(), Handle(THREAD, klass->class_loader()),
           Handle(THREAD, klass->protection_domain()), true, CHECK_false);
-      klass->class_loader_data()->record_dependency(from_class, CHECK_false);
       bool result = InstanceKlass::cast(from_class)->is_subclass_of(this_class());
       if (result && DumpSharedSpaces) {
         if (klass()->is_subclass_of(from_class) && klass()->is_subclass_of(this_class())) {

src/share/vm/classfile/verifier.cpp

 /*
- * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1949,11 +1949,9 @@ Klass* ClassVerifier::load_class(Symbol* name, TRAPS) {
   oop loader = current_class()->class_loader();
   oop protection_domain = current_class()->protection_domain();
 
-  Klass* kls = SystemDictionary::resolve_or_fail(
+  return SystemDictionary::resolve_or_fail(
     name, Handle(THREAD, loader), Handle(THREAD, protection_domain),
     true, CHECK_NULL);
-  current_class()->class_loader_data()->record_dependency(kls, CHECK_NULL);
-  return kls;
 }
 
 bool ClassVerifier::is_protected_access(instanceKlassHandle this_class,

src/share/vm/oops/constantPool.cpp

@@ -339,8 +339,6 @@ Klass* ConstantPool::klass_at_impl(constantPoolHandle this_oop, int which, TRAPS
       // Only updated constant pool - if it is resolved.
       do_resolve = this_oop->tag_at(which).is_unresolved_klass();
       if (do_resolve) {
-        ClassLoaderData* this_key = this_oop->pool_holder()->class_loader_data();
-        this_key->record_dependency(k(), CHECK_NULL); // Can throw OOM
         this_oop->klass_at_put(which, k());
       }
     }

src/share/vm/prims/jvm.cpp

@@ -991,12 +991,6 @@ JVM_ENTRY(jclass, JVM_FindClassFromClass(JNIEnv *env, const char *name,
   Handle h_prot  (THREAD, protection_domain);
   jclass result = find_class_from_class_loader(env, h_name, init, h_loader,
                                                h_prot, true, thread);
-  if (result != NULL) {
-    oop mirror = JNIHandles::resolve_non_null(result);
-    Klass* to_class = java_lang_Class::as_Klass(mirror);
-    ClassLoaderData* cld = ClassLoaderData::class_loader_data(h_loader());
-    cld->record_dependency(to_class, CHECK_NULL);
-  }
 
   if (TraceClassResolution && result != NULL) {
     // this function is generally only used for class loading during verification.

test/runtime/ClassUnload/ConstantPoolDependsTest.java

+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test ConstantPoolDependsTest
+ * @bug 8210094
+ * @summary Create ClassLoader dependency from initiating loader to class loader through constant pool reference
+ * @modules java.base/jdk.internal.misc
+ *          java.compiler
+ * @library /testlibrary /testlibrary/whitebox /runtime/testlibrary
+ * @build sun.hotspot.WhiteBox
+ * @compile p2/c2.java MyDiffClassLoader.java
+ * @run main ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI ConstantPoolDependsTest
+ */
+
+import sun.hotspot.WhiteBox;
+
+
+public class ConstantPoolDependsTest {
+    public static WhiteBox wb = WhiteBox.getWhiteBox();
+    public static final String MY_TEST = "ConstantPoolDependsTest$c1c";
+
+    public static class c1c {
+        private void test() throws Exception {
+            // ConstantPool.klass_at_impl loads through constant pool and creates dependency
+            p2.c2 c2_obj = new p2.c2();
+            c2_obj.method2();
+        }
+
+        public c1c () throws Exception {
+            test();
+            ClassUnloadCommon.triggerUnloading();  // should not unload anything
+            test();
+            ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        }
+    }
+
+    static void test() throws Throwable {
+
+        // now use the same loader to load class MyTest
+        Class MyTest_class = new MyDiffClassLoader(MY_TEST).loadClass(MY_TEST);
+
+        try {
+            // Call MyTest to load p2.c2 twice and call p2.c2.method2
+            MyTest_class.newInstance();
+        } catch (Exception e) {
+            throw new RuntimeException("Test FAILED if NoSuchMethodException is thrown");
+        }
+        ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        ClassUnloadCommon.failIf(!wb.isClassAlive(MY_TEST), "should not be unloaded");
+        ClassUnloadCommon.failIf(!wb.isClassAlive("p2.c2"), "should not be unloaded");
+        // Unless MyTest_class is referenced here, the compiler can unload it.
+        System.out.println("Should not unload anything before here because " + MyTest_class + " is still alive.");
+    }
+
+    public static void main(String args[]) throws Throwable {
+        test();
+        ClassUnloadCommon.triggerUnloading();  // should unload
+        System.gc();
+        System.out.println("Should unload p2.c2 just now");
+        ClassUnloadCommon.failIf(wb.isClassAlive(MY_TEST), "should be unloaded");
+        ClassUnloadCommon.failIf(wb.isClassAlive("p2.c2"), "should be unloaded");
+    }
+}

test/runtime/ClassUnload/DictionaryDependsTest.java

+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test DictionaryDependsTest
+ * @bug 8210094
+ * @summary Create ClassLoader dependency from initiating loader to class loader through reflection
+ * @modules java.base/jdk.internal.misc
+ *          java.compiler
+ * @library /testlibrary /testlibrary/whitebox /runtime/testlibrary
+ * @build sun.hotspot.WhiteBox
+ * @compile p2/c2.java MyDiffClassLoader.java
+ * @run main ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI DictionaryDependsTest
+ */
+import sun.hotspot.WhiteBox;
+import java.lang.reflect.Method;
+
+public class DictionaryDependsTest {
+    public static WhiteBox wb = WhiteBox.getWhiteBox();
+    public static final String MY_TEST = "DictionaryDependsTest$c1r";
+
+    static public class c1r {
+
+        private void test() throws Exception {
+            // forName loads through reflection and doesn't create dependency
+            Class<?> x = Class.forName("p2.c2", true, c1r.class.getClassLoader());
+            Method m = x.getMethod("method2");
+            java.lang.Object t = x.newInstance();
+            m.invoke(t);
+        }
+
+        public c1r () throws Exception {
+            test();
+            ClassUnloadCommon.triggerUnloading();  // should unload p2.c2
+            test();
+            ClassUnloadCommon.triggerUnloading();  // should unload p2.c2
+        }
+    }
+
+    public void test() throws Throwable {
+
+        // now use the same loader to load class MyTest
+        Class MyTest_class = new MyDiffClassLoader(MY_TEST).loadClass(MY_TEST);
+
+        try {
+            // Call MyTest to load p2.c2 twice and call p2.c2.method2
+            MyTest_class.newInstance();
+        } catch (Exception e) {
+            System.out.println("Not expected NSME");
+            throw new RuntimeException("Not expecting NSME");
+        }
+        ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        ClassUnloadCommon.failIf(!wb.isClassAlive(MY_TEST), "should not be unloaded");
+        ClassUnloadCommon.failIf(!wb.isClassAlive("p2.c2"), "should not be unloaded");
+        // Unless MyTest_class is referenced here, the compiler can unload it.
+        System.out.println("Should not unload anything before here because " + MyTest_class + " is still alive.");
+    }
+
+    public static void main(String args[]) throws Throwable {
+        DictionaryDependsTest d = new DictionaryDependsTest();
+        d.test();
+        ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        System.out.println("Should unload MyTest and p2.c2 just now");
+        ClassUnloadCommon.failIf(wb.isClassAlive(MY_TEST), "should be unloaded");
+        ClassUnloadCommon.failIf(wb.isClassAlive("p2.c2"), "should be unloaded");
+    }
+}

test/runtime/ClassUnload/MyDiffClassLoader.java

+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import java.io.*;
+import com.oracle.java.testlibrary.InMemoryJavaCompiler;
+
+public class MyDiffClassLoader extends ClassLoader {
+
+    public String loaderName;
+    public static boolean switchClassData = false;
+
+    MyDiffClassLoader(String name) {
+        this.loaderName = name;
+    }
+
+    public Class loadClass(String name) throws ClassNotFoundException {
+        if (!name.contains("c1r") &&
+            !name.contains("c1c") &&
+            !name.contains("c1s") &&
+            !name.equals("p2.c2")) {
+                return super.loadClass(name);
+        }
+
+        // new loader loads p2.c2
+        if  (name.equals("p2.c2") && !loaderName.equals("C2Loader")) {
+            Class<?> c = new MyDiffClassLoader("C2Loader").loadClass(name);
+            switchClassData = true;
+            return c;
+        }
+
+        byte[] data = switchClassData ? getNewClassData(name) : getClassData(name);
+        System.out.println("name is " + name);
+        return defineClass(name, data, 0, data.length);
+    }
+    byte[] getClassData(String name) {
+        try {
+           String TempName = name.replaceAll("\\.", "/");
+           String currentDir = System.getProperty("test.classes");
+           String filename = currentDir + File.separator + TempName + ".class";
+           FileInputStream fis = new FileInputStream(filename);
+           byte[] b = new byte[5000];
+           int cnt = fis.read(b, 0, 5000);
+           byte[] c = new byte[cnt];
+           for (int i=0; i<cnt; i++) c[i] = b[i];
+             return c;
+        } catch (IOException e) {
+           return null;
+        }
+    }
+
+    // Return p2.c2 with everything removed
+    byte[] getNewClassData(String name) {
+        return InMemoryJavaCompiler.compile("p2.c2", "package p2; public class c2 { }");
+    }
+}

test/runtime/ClassUnload/SuperDependsTest.java

+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test SuperDependsTest
+ * @bug 8210094
+ * @summary Create ClassLoader dependency from initiating loader to class loader through subclassing
+ * @modules java.base/jdk.internal.misc
+ *          java.compiler
+ * @library /testlibrary /testlibrary/whitebox /runtime/testlibrary
+ * @build sun.hotspot.WhiteBox
+ * @compile p2/c2.java MyDiffClassLoader.java
+ * @run main ClassFileInstaller sun.hotspot.WhiteBox
+ *                              sun.hotspot.WhiteBox$WhiteBoxPermission
+ * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI SuperDependsTest
+ */
+import sun.hotspot.WhiteBox;
+import p2.*;
+
+public class SuperDependsTest {
+    public static WhiteBox wb = WhiteBox.getWhiteBox();
+    public static final String MY_TEST = "SuperDependsTest$c1s";
+
+
+    // p2.c2 loads through super class and creates dependency
+    public static class c1s extends p2.c2 {
+
+        private void test() throws Exception {
+            method2();
+        }
+
+        public c1s () throws Exception {
+            test();
+            ClassUnloadCommon.triggerUnloading();  // should not unload anything
+            test();
+        }
+    }
+
+    public void test() throws Throwable {
+
+        // now use the same loader to load class MyTest
+        Class MyTest_class = new MyDiffClassLoader(MY_TEST).loadClass(MY_TEST);
+
+        // Call MyTest to load p2.c2 twice and call p2.c2.method2
+        MyTest_class.newInstance();
+        ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        ClassUnloadCommon.failIf(!wb.isClassAlive(MY_TEST), "should not be unloaded");
+        ClassUnloadCommon.failIf(!wb.isClassAlive("p2.c2"), "should not be unloaded");
+        // Unless MyTest_class is referenced here, the compiler can unload it.
+        System.out.println("Should not unload anything before here because " + MyTest_class + " is still alive.");
+    }
+
+    public static void main(String args[]) throws Throwable {
+        SuperDependsTest d = new SuperDependsTest();
+        d.test();
+        ClassUnloadCommon.triggerUnloading();  // should not unload anything
+        System.out.println("Should unload MyTest and p2.c2 just now");
+        ClassUnloadCommon.failIf(wb.isClassAlive(MY_TEST), "should be unloaded");
+        ClassUnloadCommon.failIf(wb.isClassAlive("p2.c2"), "should be unloaded");
+    }
+}

test/runtime/ClassUnload/p2/c2.java

+/*
+ * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package p2;
+
+public class c2 {
+    int i;
+    public void method2() { i = 5; System.out.println("c2 method2 called"); }
+}