anmolanmol1234 commented on code in PR #6633: URL: https://github.com/apache/hadoop/pull/6633#discussion_r1542777422
########## hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/kac/KeepAliveCache.java: ########## @@ -0,0 +1,317 @@ +/** + * 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.hadoop.fs.azurebfs.services.kac; + +import java.io.IOException; +import java.io.NotSerializableException; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.Map; + +import org.apache.hadoop.classification.VisibleForTesting; +import org.apache.http.HttpClientConnection; +import org.apache.http.conn.routing.HttpRoute; + +import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.DEFAULT_MAX_CONN_SYS_PROP; +import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.HTTP_MAX_CONN_SYS_PROP; +import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.KAC_CONN_TTL; + +/** + * Connection-pooling heuristics adapted from JDK's connection pooling `KeepAliveCache` + * <p> + * Why this implementation is required in comparison to {@link org.apache.http.impl.conn.PoolingHttpClientConnectionManager} + * connection-pooling: + * <ol> + * <li>PoolingHttpClientConnectionManager heuristic caches all the reusable connections it has created. + * JDK's implementation only caches limited number of connections. The limit is given by JVM system + * property "http.maxConnections". If there is no system-property, it defaults to 5.</li> + * <li>In PoolingHttpClientConnectionManager, it expects the application to provide `setMaxPerRoute` and `setMaxTotal`, + * which the implementation uses as the total number of connections it can create. For application using ABFS, it is not + * feasible to provide a value in the initialisation of the connectionManager. JDK's implementation has no cap on the + * number of connections it can create.</li> + * </ol> + */ +public final class KeepAliveCache + extends HashMap<KeepAliveCache.KeepAliveKey, KeepAliveCache.ClientVector> + implements Runnable { + + private boolean threadShouldPause = true; + + private boolean threadShouldRun = true; + + private int maxConn; + + private KeepAliveCache() { + Thread thread = new Thread(this); + thread.start(); + setMaxConn(); + } + + private void setMaxConn() { + String sysPropMaxConn = System.getProperty(HTTP_MAX_CONN_SYS_PROP); + if (sysPropMaxConn == null) { + maxConn = DEFAULT_MAX_CONN_SYS_PROP; + } else { + maxConn = Integer.parseInt(sysPropMaxConn); + } + } + + private static final KeepAliveCache INSTANCE = new KeepAliveCache(); + + @VisibleForTesting + void close() { + clear(); + setMaxConn(); + } + + public static KeepAliveCache getInstance() { + return INSTANCE; + } + + @VisibleForTesting + void pauseThread() { + threadShouldPause = false; + } + + @VisibleForTesting + void resumeThread() { + threadShouldPause = true; + } + + private int getKacSize() { + return INSTANCE.maxConn; + } + + @Override + public void run() { + while (threadShouldRun) { Review Comment: can be changed to while(true) as see that this variable is never changed to false -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
