azagrebin commented on a change in pull request #9997: [FLINK-14522] Introduce JavaGcCleanerWrapper to find Java GC Cleaner depending on JVM version URL: https://github.com/apache/flink/pull/9997#discussion_r340083572
########## File path: flink-core/src/main/java/org/apache/flink/util/JavaGcCleanerWrapper.java ########## @@ -0,0 +1,216 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.util; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.lang.reflect.InvocationTargetException; +import java.lang.reflect.Method; +import java.util.Arrays; +import java.util.Collection; + +/** + * Java GC Cleaner wrapper. + * + * <p>A clean operation can be wrapped with the Java GC Cleaner + * which will schedule this operation before GC is run for the given owner object (not reachable in user code). + * but only if the cleaner has not been already run explicitly by user before. + * If the cleaner is run after GC it will not run clean operation again. + * This way we guarantee that the clean operation will always run at some point but only once. + * + * <p>The wrapper looks up the underlying Java GC Cleaner class in different packages + */ +public class JavaGcCleanerWrapper { + private static final Logger LOG = LoggerFactory.getLogger(JavaGcCleanerWrapper.class); + + private static final String LEGACY_CLEANER_CLASS_NAME = "sun.misc.Cleaner"; // before Java 9 + private static final String JAVA9_CLEANER_CLASS_NAME = "java.lang.ref.Cleaner"; // since Java 9+ + + private static final Collection<CleanerProvider> CLEANER_PROVIDERS = + Arrays.asList(LegacyCleanerProvider.INSTANCE, Java9CleanerProvider.INSTANCE); + private static final CleanerFactory CLEANER_FACTORY = findGcCleaner(); + + private static CleanerFactory findGcCleaner() { + Class<?> foundCleanerClass = null; + CleanerProvider foundCleanerProviver = null; + Throwable t = null; + for (CleanerProvider cleanerProvider : CLEANER_PROVIDERS) { + try { + foundCleanerClass = Class.forName(cleanerProvider.getCleanerClassName()); + foundCleanerProviver = cleanerProvider; + break; + } catch (ClassNotFoundException e) { + t = ExceptionUtils.firstOrSuppressed(e, t); + } + } + + if (foundCleanerClass == null) { + throw new FlinkRuntimeException( + String.format("A proper Java Cleaner class is not found among %s", CLEANER_PROVIDERS), Review comment: Do you think `CLEANER_PROVIDERS` should be an enum? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
