ben-manes commented on a change in pull request #7409: URL: https://github.com/apache/pinot/pull/7409#discussion_r711188514
########## File path: pinot-common/src/main/java/org/apache/pinot/common/function/JsonPathMapCache.java ########## @@ -0,0 +1,61 @@ +/** + * 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.pinot.common.function; + +import com.jayway.jsonpath.JsonPath; +import com.jayway.jsonpath.spi.cache.Cache; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; + +/** + * This cache for avoiding repeatedly compiling JSON path string when using jsonPathXXX transformations + * + * <p>The existing jay way LRUCache is very inefficient, It will cause + * a lot of unnecessary lock waits during high concurrent data ingestion, + * and LRU mechanism is inappropriate for Pinot bounded size of the + * transformation config, so we should use this simple Map cache instead + * of it. Review comment: It's not a problem. I co-authored Guava's so either way my code is used. 😄 @Ferrari6 is correct in what your preference and default should be, though. Prior to my involvement, the Guava team bet on reference caching (MapMaker) and spent their complexity budget by forking the hash table as an optimization. This was a mistake because soft references can cause GC death spirals of stop the world events and unpredictable evictions, but looked fine in a naive benchmark. This blew their complexity budget, so porting size eviction from [CLHM](https://github.com/ben-manes/concurrentlinkedhashmap) favored simplicity over performance. The longer-term problem you'll face is that no one maintains CacheBuilder. The last big change was adding Map.compute, but it was riddled with major bugs and done inefficiently. I fixed some of those problems, but there are show stoppers. If you keep to the historic functionality then Guava's can be made acceptable in most cases. Caffeine does have jar bloat by code generating per-configuration entry classes to minimize the memory footprint. In those cases where disk is a premium some projects embed CLHM into their code base, e.g. msjdbc and groovy. You'll probably have many caches throughout Pinot making the Caffeine dependency worthwhile even if you can get by in a case-by-case basis. -- 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: commits-unsubscr...@pinot.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
