Github user tillrohrmann commented on a diff in the pull request: https://github.com/apache/flink/pull/5701#discussion_r175730158 --- Diff: flink-runtime/src/main/java/org/apache/flink/runtime/taskexecutor/AccumulatorReport.java --- @@ -0,0 +1,41 @@ +/* + * 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.flink.runtime.taskexecutor; + +import org.apache.flink.runtime.accumulators.AccumulatorSnapshot; + +import java.io.Serializable; +import java.util.Iterator; +import java.util.List; + +/** + * A report about the current values of all accumulators of the TaskExecutor for a given job. + */ +public class AccumulatorReport implements Serializable, Iterable<AccumulatorSnapshot> { --- End diff -- I think it would be better to not implement `Iterable`. `AccumulatorReport` is a value class which contains a `Collection` of `AccumulatorSnapshot`. Thus, it should be as simple as this. By letting this class implement the `Iterable` interface it basically means that `AccumulatorReport` can be used in places where an `Iterable` is usable. I think this should not be the case for this class. My concern is that we only let it implement this interface to cut a corner when iterating over the list of `AccumulatorSnapshots`.
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