[ 
https://issues.apache.org/jira/browse/FLINK-8487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16390208#comment-16390208
 ] 

ASF GitHub Bot commented on FLINK-8487:
---------------------------------------

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

    https://github.com/apache/flink/pull/5656#discussion_r172980585
  
    --- Diff: 
flink-tests/src/test/java/org/apache/flink/test/checkpointing/ZooKeeperHighAvailabilityITCase.java
 ---
    @@ -0,0 +1,333 @@
    +/*
    + * 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.test.checkpointing;
    +
    +import org.apache.flink.api.common.JobID;
    +import org.apache.flink.api.common.functions.RichMapFunction;
    +import org.apache.flink.api.common.restartstrategy.RestartStrategies;
    +import org.apache.flink.api.common.state.ValueStateDescriptor;
    +import org.apache.flink.api.common.time.Deadline;
    +import org.apache.flink.api.common.time.Time;
    +import org.apache.flink.api.common.typeutils.base.StringSerializer;
    +import org.apache.flink.client.program.ClusterClient;
    +import org.apache.flink.configuration.ConfigConstants;
    +import org.apache.flink.configuration.Configuration;
    +import org.apache.flink.configuration.HighAvailabilityOptions;
    +import org.apache.flink.configuration.TaskManagerOptions;
    +import org.apache.flink.core.testutils.OneShotLatch;
    +import org.apache.flink.runtime.concurrent.FutureUtils;
    +import org.apache.flink.runtime.jobgraph.JobGraph;
    +import org.apache.flink.runtime.jobgraph.JobStatus;
    +import org.apache.flink.runtime.state.FunctionInitializationContext;
    +import org.apache.flink.runtime.state.FunctionSnapshotContext;
    +import org.apache.flink.runtime.state.StateBackend;
    +import org.apache.flink.runtime.state.filesystem.FsStateBackend;
    +import org.apache.flink.runtime.testingUtils.TestingUtils;
    +import org.apache.flink.streaming.api.checkpoint.CheckpointedFunction;
    +import org.apache.flink.streaming.api.datastream.DataStreamSource;
    +import 
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    +import org.apache.flink.streaming.api.functions.source.SourceFunction;
    +import org.apache.flink.test.util.MiniClusterResource;
    +import org.apache.flink.util.Preconditions;
    +import org.apache.flink.util.TestLogger;
    +
    +import org.apache.curator.test.TestingServer;
    +import org.junit.AfterClass;
    +import org.junit.BeforeClass;
    +import org.junit.ClassRule;
    +import org.junit.Test;
    +import org.junit.rules.TemporaryFolder;
    +
    +import java.io.File;
    +import java.time.Duration;
    +import java.util.UUID;
    +import java.util.concurrent.CompletableFuture;
    +import java.util.concurrent.atomic.AtomicBoolean;
    +import java.util.concurrent.atomic.AtomicInteger;
    +
    +import static org.hamcrest.core.Is.is;
    +import static org.junit.Assert.assertEquals;
    +import static org.junit.Assert.assertNotNull;
    +import static org.junit.Assert.assertThat;
    +import static org.junit.Assert.assertTrue;
    +
    +/**
    + * Integration tests for {@link 
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore}.
    + */
    +public class ZooKeeperHighAvailabilityITCase extends TestLogger {
    --- End diff --
    
    I have similar comments for this test as for #5654 - the test is fins in 
general, but can probably be simplified slightly, plus a bit of code style 
cleanup.


> State loss after multiple restart attempts
> ------------------------------------------
>
>                 Key: FLINK-8487
>                 URL: https://issues.apache.org/jira/browse/FLINK-8487
>             Project: Flink
>          Issue Type: Bug
>          Components: State Backends, Checkpointing
>    Affects Versions: 1.3.2
>            Reporter: Fabian Hueske
>            Priority: Blocker
>             Fix For: 1.5.0, 1.4.3
>
>
> A user [reported this 
> issue|https://lists.apache.org/thread.html/9dc9b719cf8449067ad01114fedb75d1beac7b4dff171acdcc24903d@%3Cuser.flink.apache.org%3E]
>  on the user@f.a.o mailing list and analyzed the situation.
> Scenario:
> - A program that reads from Kafka and computes counts in a keyed 15 minute 
> tumbling window.  StateBackend is RocksDB and checkpointing is enabled.
> {code}
> keyBy(0)
>         .timeWindow(Time.of(window_size, TimeUnit.MINUTES))
>         .allowedLateness(Time.of(late_by, TimeUnit.SECONDS))
>         .reduce(new ReduceFunction(), new WindowFunction())
> {code}
> - At some point HDFS went into a safe mode due to NameNode issues
> - The following exception was thrown
> {code}
> org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.ipc.StandbyException):
>  Operation category WRITE is not supported in state standby. Visit 
> https://s.apache.org/sbnn-error
>     ..................
>     at 
> org.apache.flink.runtime.fs.hdfs.HadoopFileSystem.mkdirs(HadoopFileSystem.java:453)
>         at 
> org.apache.flink.core.fs.SafetyNetWrapperFileSystem.mkdirs(SafetyNetWrapperFileSystem.java:111)
>         at 
> org.apache.flink.runtime.state.filesystem.FsCheckpointStreamFactory.createBasePath(FsCheckpointStreamFactory.java:132)
> {code}
> - The pipeline came back after a few restarts and checkpoint failures, after 
> the HDFS issues were resolved.
> - It was evident that operator state was lost. Either it was the Kafka 
> consumer that kept on advancing it's offset between a start and the next 
> checkpoint failure (a minute's worth) or the the operator that had partial 
> aggregates was lost. 
> The user did some in-depth analysis (see [mail 
> thread|https://lists.apache.org/thread.html/9dc9b719cf8449067ad01114fedb75d1beac7b4dff171acdcc24903d@%3Cuser.flink.apache.org%3E])
>  and might have (according to [~aljoscha]) identified the problem.
> [~stefanrichte...@gmail.com], can you have a look at this issue and check if 
> it is relevant?



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