eolivelli commented on a change in pull request #509: Issue 508: Introduce lifecycle components for managing components in bookie server URL: https://github.com/apache/bookkeeper/pull/509#discussion_r139104148
########## File path: bookkeeper-common/src/main/java/org/apache/bookkeeper/common/component/ComponentStarter.java ########## @@ -0,0 +1,71 @@ +/* + * 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.bookkeeper.common.component; + +import java.util.concurrent.CountDownLatch; +import lombok.extern.slf4j.Slf4j; + +/** + * Utils to start components. + */ +@Slf4j +public class ComponentStarter { + + static class ComponentShutdownHook implements Runnable { + + private final LifecycleComponent component; + private final CountDownLatch aliveLatch; + + ComponentShutdownHook(LifecycleComponent component, + CountDownLatch aliveLatch) { + this.component = component; + this.aliveLatch = aliveLatch; + } + + @Override + public void run() { + aliveLatch.countDown(); + log.info("Closing component {} in shutdown hook.", component.getName()); + try { + component.close(); + log.info("Closed component {} in shutdown hook successfully. Exiting.", component.getName()); + } catch (Exception e) { + log.error("Failed to close component {} in shutdown hook gracefully, Exiting anyway", + component.getName(), e); + } + } + + } + + /** + * Start a component and register a shutdown hook. + * + * @param component component to start. + */ + public static void startComponent(LifecycleComponent component, + CountDownLatch aliveLatch) { + Runtime.getRuntime().addShutdownHook(new Thread( Review comment: this is not good. On unit tests for instance we are going to pollute the Java Runtime with shutdownhooks. Shutdown hooks introduce a lot of troubles and in my experience I saw a lot of deadlocks. I would like to drop this if there is no strong evidence of benefit. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on 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
