8054402: "klass->is_loader_alive(_is_alive)) failed: must be alive" for anonymous classes
Summary: Because anonymous classes are not in the system dictionary, we have to set 'unloading_occurred' based on 'CLDG::do_unloading()'. Added jtreg test.
Reviewed-by: kvn, coleenp
--- a/hotspot/src/share/vm/classfile/dictionary.cpp Wed Aug 13 17:37:11 2014 -0700
+++ b/hotspot/src/share/vm/classfile/dictionary.cpp Thu Aug 14 09:15:39 2014 +0200
@@ -130,15 +130,13 @@
}
-bool Dictionary::do_unloading() {
+void Dictionary::do_unloading() {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
- bool class_was_unloaded = false;
- int index = 0; // Defined here for portability! Do not move
// Remove unloadable entries and classes from system dictionary
// The placeholder array has been handled in always_strong_oops_do.
DictionaryEntry* probe = NULL;
- for (index = 0; index < table_size(); index++) {
+ for (int index = 0; index < table_size(); index++) {
for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
probe = *p;
Klass* e = probe->klass();
@@ -158,16 +156,8 @@
// 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). Note that this is
- // not the same as unloading the referred class.
- if (k_def_class_loader_data == loader_data) {
- // This is the defining entry, so the referred class is about
- // to be unloaded.
- class_was_unloaded = true;
- }
- // Also remove this system dictionary entry.
+ // 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)
@@ -196,7 +186,6 @@
p = probe->next_addr();
}
}
- return class_was_unloaded;
}
void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
--- a/hotspot/src/share/vm/classfile/dictionary.hpp Wed Aug 13 17:37:11 2014 -0700
+++ b/hotspot/src/share/vm/classfile/dictionary.hpp Thu Aug 14 09:15:39 2014 +0200
@@ -108,9 +108,8 @@
return (loader_data->is_the_null_class_loader_data() || !ClassUnloading);
}
- // Unload (that is, break root links to) all unmarked classes and
- // loaders. Returns "true" iff something was unloaded.
- bool do_unloading();
+ // Unload (that is, break root links to) all unmarked classes and loaders.
+ void do_unloading();
// Protection domains
Klass* find(int index, unsigned int hash, Symbol* name,
--- a/hotspot/src/share/vm/classfile/systemDictionary.cpp Wed Aug 13 17:37:11 2014 -0700
+++ b/hotspot/src/share/vm/classfile/systemDictionary.cpp Thu Aug 14 09:15:39 2014 +0200
@@ -1661,10 +1661,9 @@
// Note: anonymous classes are not in the SD.
bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
// First, mark for unload all ClassLoaderData referencing a dead class loader.
- bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
- bool unloading_occurred = false;
- if (has_dead_loaders) {
- unloading_occurred = dictionary()->do_unloading();
+ bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive);
+ if (unloading_occurred) {
+ dictionary()->do_unloading();
constraints()->purge_loader_constraints();
resolution_errors()->purge_resolution_errors();
}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/classUnloading/anonymousClass/TestAnonymousClassUnloading.java Thu Aug 14 09:15:39 2014 +0200
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2014, 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 sun.hotspot.WhiteBox;
+import sun.misc.Unsafe;
+import sun.misc.IOUtils;
+
+import java.lang.reflect.Method;
+import java.net.URL;
+import java.net.URLConnection;
+
+/*
+ * @test TestAnonymousClassUnloading
+ * @bug 8054402
+ * @summary "Tests unloading of anonymous classes."
+ * @library /testlibrary /testlibrary/whitebox
+ * @compile TestAnonymousClassUnloading.java
+ * @run main ClassFileInstaller TestAnonymousClassUnloading sun.hotspot.WhiteBox
+ * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -XX:-BackgroundCompilation TestAnonymousClassUnloading
+ */
+public class TestAnonymousClassUnloading {
+ private static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();
+ private static final Unsafe UNSAFE = Unsafe.getUnsafe();
+ private static int COMP_LEVEL_SIMPLE = 1;
+ private static int COMP_LEVEL_FULL_OPTIMIZATION = 4;
+
+ /**
+ * We override hashCode here to be able to access this implementation
+ * via an Object reference (we cannot cast to TestAnonymousClassUnloading).
+ */
+ @Override
+ public int hashCode() {
+ return 42;
+ }
+
+ /**
+ * Does some work by using the anonymousClass.
+ * @param anonymousClass Class performing some work (will be unloaded)
+ */
+ static private void doWork(Class<?> anonymousClass) throws InstantiationException, IllegalAccessException {
+ // Create a new instance
+ Object anon = anonymousClass.newInstance();
+ // We would like to call a method of anonymousClass here but we cannot cast because the class
+ // was loaded by a different class loader. One solution would be to use reflection but since
+ // we want C2 to implement the call as an IC we call Object::hashCode() here which actually
+ // calls anonymousClass::hashCode(). C2 will then implement this call as an IC.
+ if (anon.hashCode() != 42) {
+ new RuntimeException("Work not done");
+ }
+ }
+
+ /**
+ * Makes sure that method is compiled by forcing compilation if not yet compiled.
+ * @param m Method to be checked
+ */
+ static private void makeSureIsCompiled(Method m) {
+ // Make sure background compilation is disabled
+ if (WHITE_BOX.getBooleanVMFlag("BackgroundCompilation")) {
+ throw new RuntimeException("Background compilation enabled");
+ }
+
+ // Check if already compiled
+ if (!WHITE_BOX.isMethodCompiled(m)) {
+ // If not, try to compile it with C2
+ if(!WHITE_BOX.enqueueMethodForCompilation(m, COMP_LEVEL_FULL_OPTIMIZATION)) {
+ // C2 compiler not available, try to compile with C1
+ WHITE_BOX.enqueueMethodForCompilation(m, COMP_LEVEL_SIMPLE);
+ }
+ // Because background compilation is disabled, method should now be compiled
+ if(!WHITE_BOX.isMethodCompiled(m)) {
+ throw new RuntimeException(m + " not compiled");
+ }
+ }
+ }
+
+ /**
+ * This test creates stale Klass* metadata referenced by a compiled IC.
+ *
+ * The following steps are performed:
+ * (1) An anonymous version of TestAnonymousClassUnloading is loaded by a custom class loader
+ * (2) The method doWork that calls a method of the anonymous class is compiled. The call
+ * is implemented as an IC referencing Klass* metadata of the anonymous class.
+ * (3) Unloading of the anonymous class is enforced. The IC now references dead metadata.
+ */
+ static public void main(String[] args) throws Exception {
+ // (1) Load an anonymous version of this class using the corresponding Unsafe method
+ URL classUrl = TestAnonymousClassUnloading.class.getResource("TestAnonymousClassUnloading.class");
+ URLConnection connection = classUrl.openConnection();
+ byte[] classBytes = IOUtils.readFully(connection.getInputStream(), connection.getContentLength(), true);
+ Class<?> anonymousClass = UNSAFE.defineAnonymousClass(TestAnonymousClassUnloading.class, classBytes, null);
+
+ // (2) Make sure all paths of doWork are profiled and compiled
+ for (int i = 0; i < 100000; ++i) {
+ doWork(anonymousClass);
+ }
+
+ // Make sure doWork is compiled now
+ Method doWork = TestAnonymousClassUnloading.class.getDeclaredMethod("doWork", Class.class);
+ makeSureIsCompiled(doWork);
+
+ // (3) Throw away reference to anonymousClass to allow unloading
+ anonymousClass = null;
+
+ // Force garbage collection to trigger unloading of anonymousClass
+ // Dead metadata reference to anonymousClass triggers JDK-8054402
+ WHITE_BOX.fullGC();
+ }
+}