uros-db commented on code in PR #52667: URL: https://github.com/apache/spark/pull/52667#discussion_r2470272234
########## sql/api/src/main/scala/org/apache/spark/sql/internal/util/SingletonBase.java: ########## @@ -0,0 +1,46 @@ +/* + * 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.internal.util; + +/** + * Generic abstract base class for implementing the singleton design pattern. This class is lazily + * initialized, thread-safe, and generic (it can be used to create singletons for any type `T`). Review Comment: If we just use the regular singleton approach (without lazy initialization) - then the spatial reference system mapper (and all of the 10k+ SRS objects that will have in the future) will be initialized when the class is loaded in JVM. This can also happen even on a code path that doesn't necessarily use the mapper methods at all. However, if we use lazy initialization with double-checked locking (as implemented in this PR), then we defer this initialization until after the mapper `getInstance` method is actually called for the first time. I think this is a safer approach for us (note that this also traces back to a review comment from the original PR: https://github.com/apache/spark/pull/52491#discussion_r2393531931). -- 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]
