Github user zentol commented on a diff in the pull request: https://github.com/apache/flink/pull/4665#discussion_r138724269 --- Diff: flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/windowing/WindowOperator.java --- @@ -132,6 +133,13 @@ */ protected final OutputTag<IN> lateDataOutputTag; + /** + * Metrics about the lost data due to arrive late. + * */ + protected final String loseData = "lost_data"; --- End diff -- we use camel case for naming metric names. "lost_data" in particular is also not really descriptive and the naming scheme is inconsistent with existing metrics. I suggest "numLateRecords". This string should also be static, and named `LATE_ELEMENTS_METRIC_NAME` for clarity purposes.
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