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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-5972) Don't allow shrinking merging windows
Date Wed, 22 Mar 2017 17:00:44 GMT

    [ https://issues.apache.org/jira/browse/FLINK-5972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15936684#comment-15936684
] 

ASF GitHub Bot commented on FLINK-5972:
---------------------------------------

Github user aljoscha commented on a diff in the pull request:

    https://github.com/apache/flink/pull/3587#discussion_r107471533
  
    --- Diff: flink-streaming-java/src/test/java/org/apache/flink/streaming/runtime/operators/windowing/EvictingWindowOperatorContractTest.java
---
    @@ -0,0 +1,2654 @@
    +/*
    + * 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
    + * <p>
    + * http://www.apache.org/licenses/LICENSE-2.0
    + * <p>
    + * 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.streaming.runtime.operators.windowing;
    +
    +
    +import static org.apache.flink.streaming.runtime.operators.windowing.StreamRecordMatchers.isStreamRecord;
    +import static org.hamcrest.Matchers.containsInAnyOrder;
    +import static org.junit.Assert.*;
    +import static org.mockito.Matchers.anyLong;
    +import static org.mockito.Mockito.*;
    +
    +import com.google.common.collect.Lists;
    --- End diff --
    
    I'm replacing it by `new ArrayList<>(Arrays.asList(...))`


> Don't allow shrinking merging windows
> -------------------------------------
>
>                 Key: FLINK-5972
>                 URL: https://issues.apache.org/jira/browse/FLINK-5972
>             Project: Flink
>          Issue Type: Bug
>          Components: DataStream API
>    Affects Versions: 1.1.0, 1.2.0, 1.3.0
>            Reporter: Aljoscha Krettek
>            Priority: Blocker
>             Fix For: 1.3.0, 1.2.1
>
>
> A misbehaving {{MergingWindowAssigner}} can cause a merge that results in a window that
is smaller than the span of all the merged windows. This, in itself is not problematic. It
becomes problematic when the end timestamp of a window that was not late before merging is
now earlier than the watermark (the timestamp is smaller than the watermark).
> There are two choices:
>  - immediately process the window
>  - drop the window
> processing the window will lead to late data downstream.
> The current behaviour is to silently drop the window but that logic has a bug: we only
remove the dropped window from the {{MergingWindowSet}} but we don't properly clean up state
and timers that the window still (possibly) has. We should fix this bug in the process of
resolving this issue.
> We should either just fix the bug and still silently drop windows or add a check and
throw an exception when the end timestamp falls below the watermark.



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