8276422: Add command-line option to disable finalization

Co-authored-by: David Holmes <dholmes@openjdk.org>
Co-authored-by: Brent Christian <bchristi@openjdk.org>
Reviewed-by: dholmes, kbarrett, bchristi

make/data/hotspot-symbols/symbols-unix

@@ -147,6 +147,7 @@ JVM_IsArrayClass
 JVM_IsCDSDumpingEnabled
 JVM_IsConstructorIx
 JVM_IsDumpingClassList
+JVM_IsFinalizationEnabled
 JVM_IsHiddenClass
 JVM_IsInterface
 JVM_IsPrimitiveClass

src/hotspot/share/classfile/classFileParser.cpp

@@ -2835,7 +2835,8 @@ Method* ClassFileParser::parse_method(const ClassFileStream* const cfs,
                           annotation_default_length,
                           CHECK_NULL);
 
-  if (name == vmSymbols::finalize_method_name() &&
+  if (InstanceKlass::is_finalization_enabled() &&
+      name == vmSymbols::finalize_method_name() &&
       signature == vmSymbols::void_method_signature()) {
     if (m->is_empty_method()) {
       _has_empty_finalizer = true;
@@ -4171,7 +4172,8 @@ void ClassFileParser::set_precomputed_flags(InstanceKlass* ik) {
   bool f = false;
   const Method* const m = ik->lookup_method(vmSymbols::finalize_method_name(),
                                            vmSymbols::void_method_signature());
-  if (m != NULL && !m->is_empty_method()) {
+  if (InstanceKlass::is_finalization_enabled() &&
+      (m != NULL) && !m->is_empty_method()) {
       f = true;
   }
 

src/hotspot/share/include/jvm.h

@@ -759,6 +759,9 @@ JVM_SupportsCX8(void);
 JNIEXPORT void JNICALL
 JVM_ReportFinalizationComplete(JNIEnv *env, jobject finalizee);
 
+JNIEXPORT jboolean JNICALL
+JVM_IsFinalizationEnabled(JNIEnv *env);
+
 /*************************************************************************
  PART 2: Support for the Verifier and Class File Format Checker
  ************************************************************************/

src/hotspot/share/oops/instanceKlass.cpp

@@ -141,6 +141,7 @@
 
 #endif //  ndef DTRACE_ENABLED
 
+bool InstanceKlass::_finalization_enabled = true;
 
 static inline bool is_class_loader(const Symbol* class_name,
                                    const ClassFileParser& parser) {

src/hotspot/share/oops/instanceKlass.hpp

@@ -329,7 +329,17 @@ class InstanceKlass: public Klass {
 
   static bool _disable_method_binary_search;
 
+  // Controls finalizer registration
+  static bool _finalization_enabled;
+
  public:
+
+  // Queries finalization state
+  static bool is_finalization_enabled() { return _finalization_enabled; }
+
+  // Sets finalization state
+  static void set_finalization_enabled(bool val) { _finalization_enabled = val; }
+
   // The three BUILTIN class loader types
   bool is_shared_boot_class() const {
     return (_misc_flags & _misc_is_shared_boot_class) != 0;

src/hotspot/share/prims/jvm.cpp

@@ -690,6 +690,10 @@ JVM_ENTRY(void, JVM_ReportFinalizationComplete(JNIEnv * env, jobject finalizee))
   MANAGEMENT_ONLY(FinalizerService::on_complete(JNIHandles::resolve_non_null(finalizee), THREAD);)
 JVM_END
 
+JVM_ENTRY(jboolean, JVM_IsFinalizationEnabled(JNIEnv * env))
+  return InstanceKlass::is_finalization_enabled();
+JVM_END
+
 // java.io.File ///////////////////////////////////////////////////////////////
 
 JVM_LEAF(char*, JVM_NativePath(char* path))

src/hotspot/share/runtime/arguments.cpp

@@ -40,6 +40,7 @@
 #include "logging/logStream.hpp"
 #include "logging/logTag.hpp"
 #include "memory/allocation.inline.hpp"
+#include "oops/instanceKlass.hpp"
 #include "oops/oop.inline.hpp"
 #include "prims/jvmtiExport.hpp"
 #include "runtime/arguments.hpp"
@@ -2887,6 +2888,17 @@ jint Arguments::parse_each_vm_init_arg(const JavaVMInitArgs* args, bool* patch_m
       if (FLAG_SET_CMDLINE(ErrorFileToStdout, true) != JVMFlag::SUCCESS) {
         return JNI_EINVAL;
       }
+    } else if (match_option(option, "--finalization=", &tail)) {
+      if (strcmp(tail, "enabled") == 0) {
+        InstanceKlass::set_finalization_enabled(true);
+      } else if (strcmp(tail, "disabled") == 0) {
+        InstanceKlass::set_finalization_enabled(false);
+      } else {
+        jio_fprintf(defaultStream::error_stream(),
+                    "Invalid finalization value '%s', must be 'disabled' or 'enabled'.\n",
+                    tail);
+        return JNI_EINVAL;
+      }
     } else if (match_option(option, "-XX:+ExtendedDTraceProbes")) {
 #if defined(DTRACE_ENABLED)
       if (FLAG_SET_CMDLINE(ExtendedDTraceProbes, true) != JVMFlag::SUCCESS) {

src/java.base/share/classes/java/lang/ref/Finalizer.java

@@ -61,9 +61,17 @@ static ReferenceQueue<Object> getQueue() {
         return queue;
     }
 
+    static final boolean ENABLED = isFinalizationEnabled();
+
+    private static native boolean isFinalizationEnabled();
+
     /* Invoked by VM */
     static void register(Object finalizee) {
-        new Finalizer(finalizee);
+        if (ENABLED) {
+            new Finalizer(finalizee);
+        } else {
+            throw new InternalError("unexpected call to Finalizer::register when finalization is disabled");
+        }
     }
 
     private void runFinalizer(JavaLangAccess jla) {
@@ -130,7 +138,7 @@ public Void run() {
 
     /* Called by Runtime.runFinalization() */
     static void runFinalization() {
-        if (VM.initLevel() == 0) {
+        if (VM.initLevel() == 0 || ! ENABLED) {
             return;
         }
 
@@ -182,14 +190,16 @@ public void run() {
     }
 
     static {
-        ThreadGroup tg = Thread.currentThread().getThreadGroup();
-        for (ThreadGroup tgn = tg;
-             tgn != null;
-             tg = tgn, tgn = tg.getParent());
-        Thread finalizer = new FinalizerThread(tg);
-        finalizer.setPriority(Thread.MAX_PRIORITY - 2);
-        finalizer.setDaemon(true);
-        finalizer.start();
+        if (ENABLED) {
+            ThreadGroup tg = Thread.currentThread().getThreadGroup();
+            for (ThreadGroup tgn = tg;
+                 tgn != null;
+                 tg = tgn, tgn = tg.getParent());
+            Thread finalizer = new FinalizerThread(tg);
+            finalizer.setPriority(Thread.MAX_PRIORITY - 2);
+            finalizer.setDaemon(true);
+            finalizer.start();
+        }
     }
 
 }

src/java.base/share/classes/sun/launcher/resources/launcher.properties

@@ -194,7 +194,10 @@ java.launcher.X.usage=\n\
 \                      override or augment a module with classes and resources\n\
 \                      in JAR files or directories.\n\
 \    --source <version>\n\
-\                      set the version of the source in source-file mode.\n\n\
+\                      set the version of the source in source-file mode.\n\
+\    --finalization=<value>\n\
+\                      controls finalization\n\
+\                      <value> is one of "enabled" or "disabled"\n\n\
 These extra options are subject to change without notice.\n
 
 # Translators please note do not translate the options themselves

src/java.base/share/native/libjava/Finalizer.c

@@ -32,4 +32,7 @@ Java_java_lang_ref_Finalizer_reportComplete(JNIEnv* env, jclass cls, jobject fin
     JVM_ReportFinalizationComplete(env, finalizee);
 }
 
-
+JNIEXPORT jboolean JNICALL
+Java_java_lang_ref_Finalizer_isFinalizationEnabled(JNIEnv* env, jclass cls) {
+    return JVM_IsFinalizationEnabled(env);
+}

test/jdk/java/lang/Object/FinalizationOption.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2021, 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
+ * @bug 8276422
+ * @summary add command-line option to disable finalization
+ * @run main/othervm                         FinalizationOption yes
+ * @run main/othervm --finalization=enabled  FinalizationOption yes
+ * @run main/othervm --finalization=disabled FinalizationOption no
+ */
+public class FinalizationOption {
+    static volatile boolean finalizerWasCalled = false;
+
+    @SuppressWarnings("deprecation")
+    protected void finalize() {
+        finalizerWasCalled = true;
+    }
+
+    static void create() {
+        new FinalizationOption();
+    }
+
+    /**
+     * Checks whether the finalizer thread is or is not running. The finalizer thread
+     * is a thread in the root thread group whose named is "Finalizer".
+     * @param expected boolean indicating whether a finalizer thread should exist
+     * @return boolean indicating whether the expectation was met
+     */
+    static boolean checkFinalizerThread(boolean expected) {
+        ThreadGroup root = Thread.currentThread().getThreadGroup();
+        for (ThreadGroup parent = root;
+             parent != null;
+             root = parent, parent = root.getParent())
+            ;
+
+        int nt = 100;
+        Thread[] threads;
+        while (true) {
+            threads = new Thread[nt];
+            nt = root.enumerate(threads);
+            if (nt < threads.length)
+                break;
+            threads = new Thread[nt + 100];
+        }
+
+        Thread ft = null;
+        for (int i = 0; i < nt; i++) {
+            if ("Finalizer".equals(threads[i].getName())) {
+                ft = threads[i];
+                break;
+            }
+        }
+
+        String msg = (ft == null) ? "(none)" : ft.toString();
+        boolean passed = (ft != null) == expected;
+        System.out.printf("Finalizer thread.    Expected: %s   Actual: %s   %s%n",
+            expected, msg, passed ? "Passed." : "FAILED!");
+        return passed;
+    }
+
+    /**
+     * Checks whether there was a call to the finalize() method.
+     * @param expected boolean whether finalize() should be called
+     * @return boolean indicating whether the expecation was met
+     */
+    static boolean checkFinalizerCalled(boolean expected) {
+        create();
+        for (int i = 0; i < 100; i++) {
+            System.gc();
+            try {
+                Thread.sleep(10L);
+            } catch (InterruptedException ie) {
+                Thread.currentThread().interrupt();
+            }
+            if (finalizerWasCalled) {
+                break;
+            }
+        }
+        boolean passed = (expected == finalizerWasCalled);
+        System.out.printf("Call to finalize().  Expected: %s   Actual: %s   %s%n",
+            expected, finalizerWasCalled,
+            passed ? "Passed." : "FAILED!");
+        return passed;
+    }
+
+    public static void main(String[] args) {
+        boolean finalizationEnabled = switch (args[0]) {
+            case "yes" -> true;
+            case "no"  -> false;
+            default -> {
+                throw new AssertionError("usage: FinalizationOption yes|no");
+            }
+        };
+
+        boolean threadPass = checkFinalizerThread(finalizationEnabled);
+        boolean calledPass = checkFinalizerCalled(finalizationEnabled);
+
+        if (!threadPass || !calledPass)
+            throw new AssertionError("Test failed.");
+    }
+}

test/jdk/java/lang/Object/InvalidFinalizationOption.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2021, 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
+ * @bug 8276422
+ * @summary Invalid/missing values for the finalization option should be rejected
+ * @library /test/lib
+ * @run driver InvalidFinalizationOption
+ */
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class InvalidFinalizationOption {
+    public static void main(String[] args) throws Exception {
+        record TestData(String arg, String expected) { }
+
+        TestData[] testData = {
+            new TestData("--finalization",        "Unrecognized option"),
+            new TestData("--finalization=",       "Invalid finalization value"),
+            new TestData("--finalization=azerty", "Invalid finalization value")
+        };
+
+        for (var data : testData) {
+            ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(data.arg);
+            OutputAnalyzer output = new OutputAnalyzer(pb.start());
+            output.shouldContain(data.expected);
+            output.shouldHaveExitValue(1);
+        }
+    }
+}