LuciferYang commented on code in PR #39541: URL: https://github.com/apache/spark/pull/39541#discussion_r1082062813
########## connector/connect/client/jvm/src/main/scala/org/apache/spark/sql/connect/client/util/Cleaner.scala: ########## @@ -0,0 +1,113 @@ +/* + * 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.spark.sql.connect.client.util + +import java.lang.ref.{ReferenceQueue, WeakReference} +import java.util.Collections +import java.util.concurrent.ConcurrentHashMap + +import scala.collection.mutable +import scala.util.control.NonFatal + +/** + * Helper class for cleaning up an object's resources after the object itself has been garbage + * collected. + * + * When we move to Java 9+ we should replace this class by [[java.lang.ref.Cleaner]]. + */ +private[sql] class Cleaner { + class Ref(pin: AnyRef, val resource: AutoCloseable) + extends WeakReference[AnyRef](pin, referenceQueue) + with AutoCloseable { + override def close(): Unit = resource.close() + } + + def register(pin: Cleanable): Unit = { + register(pin, pin.cleaner) + } + + /** + * Register an objects' resources for clean-up. Note that it is absolutely pivotal that resource + * itself does not contain any reference to the object, if it does the object will never be + * garbage collected and the clean-up will never be performed. + * + * @param pin + * who's resources need to be cleaned up after GC. + * @param resource + * to clean-up. + */ + def register(pin: AnyRef, resource: AutoCloseable): Unit = { + referenceBuffer.add(new Ref(pin, resource)) + } + + @volatile private var stopped = false + private val referenceBuffer = Collections.newSetFromMap[Ref](new ConcurrentHashMap) + private val referenceQueue = new ReferenceQueue[AnyRef] + + private val cleanerThread = { + val thread = new Thread(() => cleanUp()) + thread.setName("cleaner") + thread.setDaemon(true) + thread + } + + def start(): Unit = { + require(!stopped) + cleanerThread.start() + } + + def stop(): Unit = { + stopped = true + cleanerThread.interrupt() + } + + private def cleanUp(): Unit = { + while (!stopped) { + try { + val ref = referenceQueue.remove().asInstanceOf[Ref] + referenceBuffer.remove(ref) + ref.close() + } catch { + case NonFatal(e) => + // Perhaps log this? + e.printStackTrace() Review Comment: Yes, I think we should use log, `e.printStackTrace` holds a global lock, which is very inefficient -- 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. To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
