[GitHub] [flink] Myasuka commented on a change in pull request #7813: [FLINK-10712] Support to restore state when using RestartPipelinedRegionStrategy

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Myasuka commented on a change in pull request #7813: [FLINK-10712] Support to restore state when using RestartPipelinedRegionStrategy
URL: https://github.com/apache/flink/pull/7813#discussion_r275452126
 
 

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 File path: flink-tests/src/test/java/org/apache/flink/test/checkpointing/RegionFailoverITCase.java
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+/*
+ * 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.functions.MapFunction;
+import org.apache.flink.api.common.functions.RichMapFunction;
+import org.apache.flink.api.common.restartstrategy.RestartStrategies;
+import org.apache.flink.api.common.state.ListState;
+import org.apache.flink.api.common.state.ListStateDescriptor;
+import org.apache.flink.api.common.state.ValueState;
+import org.apache.flink.api.common.state.ValueStateDescriptor;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.functions.KeySelector;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.client.program.ClusterClient;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.configuration.JobManagerOptions;
+import org.apache.flink.runtime.jobgraph.JobGraph;
+import org.apache.flink.runtime.state.CheckpointListener;
+import org.apache.flink.runtime.state.FunctionInitializationContext;
+import org.apache.flink.runtime.state.FunctionSnapshotContext;
+import org.apache.flink.runtime.state.KeyGroupRangeAssignment;
+import org.apache.flink.runtime.testutils.MiniClusterResourceConfiguration;
+import org.apache.flink.streaming.api.CheckpointingMode;
+import org.apache.flink.streaming.api.checkpoint.CheckpointedFunction;
+import org.apache.flink.streaming.api.checkpoint.ListCheckpointed;
+import org.apache.flink.streaming.api.datastream.DataStreamUtils;
+import org.apache.flink.streaming.api.environment.CheckpointConfig;
+import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
+import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;
+import org.apache.flink.streaming.api.functions.source.RichParallelSourceFunction;
+import org.apache.flink.test.util.MiniClusterWithClientResource;
+import org.apache.flink.util.TestLogger;
+
+import org.apache.commons.collections.CollectionUtils;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.StreamSupport;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Tests for region failover with multi regions.
+ */
+public class RegionFailoverITCase extends TestLogger {
+
+	private static final int FAIL_BASE = 1000;
+	private static final int NUM_OF_REGIONS = 3;
+	private static final int MAX_PARALLELISM = 2 * NUM_OF_REGIONS;
+	private static final Set<Integer> EXPECTED_INDICES = IntStream.range(0, NUM_OF_REGIONS).boxed().collect(Collectors.toSet());
+	private static final int NUM_OF_RESTARTS = 3;
+	private static final int NUM_ELEMENTS = FAIL_BASE * 10;
+
+	private static AtomicLong lastCompletedCheckpointId = new AtomicLong(0);
+	private static AtomicInteger numCompletedCheckpoints = new AtomicInteger(0);
+	private static AtomicInteger jobFailedCnt = new AtomicInteger(0);
+
+	private static Map<Long, Integer> snapshotIndicesOfSubTask = new HashMap<>();
+
+	private static MiniClusterWithClientResource cluster;
+
+	private static boolean restoredState = false;
+
+	@ClassRule
+	public static final TemporaryFolder TEMPORARY_FOLDER = new TemporaryFolder();
+
+	@Before
+	public void setup() throws Exception {
+		Configuration configuration = new Configuration();
+		configuration.setString(JobManagerOptions.EXECUTION_FAILOVER_STRATEGY, "region");
+
+		cluster = new MiniClusterWithClientResource(
+			new MiniClusterResourceConfiguration.Builder()
+				.setConfiguration(configuration)
+				.setNumberTaskManagers(2)
+				.setNumberSlotsPerTaskManager(2).build());
+		cluster.before();
+		jobFailedCnt.set(0);
+		numCompletedCheckpoints.set(0);
+	}
+
+	@AfterClass
+	public static void shutDownExistingCluster() {
+		if (cluster != null) {
+			cluster.after();
+			cluster = null;
+		}
+	}
+
+	/**
+	 * Tests that a simple job (Source -> Map) with multi regions could restore with operator state.
+	 *
+	 * <p>The last subtask of Map function in the 1st stream graph would fail {@code NUM_OF_RESTARTS} times,
+	 * and it will verify whether the restored state is identical to last completed checkpoint's.
+	 */
+	@Test(timeout = 60000)
+	public void testMultiRegionFailover() {
+		try {
+			JobGraph jobGraph = createJobGraph();
+			ClusterClient<?> client = cluster.getClusterClient();
+			client.submitJob(jobGraph, RegionFailoverITCase.class.getClassLoader());
+			verifyAfterJobExecuted();
+		}
+		catch (Exception e) {
+			e.printStackTrace();
+			Assert.fail(e.getMessage());
+		}
+	}
+
+	private void verifyAfterJobExecuted() {
+		Assert.assertTrue("The test multi-region job has never ever restored state.", restoredState);
+
+		for (Map<Integer, Integer> map : ValidatingSink.maps) {
+			for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
+				assertEquals(Math.min(2 * entry.getKey() + 1, NUM_ELEMENTS), (int) entry.getValue());
+			}
+		}
+	}
+
+	private JobGraph createJobGraph() {
+
+		StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
+		env.setParallelism(NUM_OF_REGIONS);
+		env.setMaxParallelism(MAX_PARALLELISM);
+		env.enableCheckpointing(200, CheckpointingMode.EXACTLY_ONCE);
+		env.getCheckpointConfig().enableExternalizedCheckpoints(CheckpointConfig.ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION);
+		env.disableOperatorChaining();
+		env.getConfig().setRestartStrategy(RestartStrategies.fixedDelayRestart(NUM_OF_RESTARTS, 0L));
+		env.getConfig().disableSysoutLogging();
+
+		// Use DataStreamUtils#reinterpretAsKeyed to avoid merge regions and this stream graph would exist num of 'NUM_OF_REGIONS' individual regions.
+		DataStreamUtils.reinterpretAsKeyedStream(
+			env.addSource(new StringGeneratingSourceFunction(NUM_ELEMENTS, NUM_ELEMENTS / NUM_OF_RESTARTS))
+				.setParallelism(NUM_OF_REGIONS),
+			(KeySelector<Tuple2<Integer, Integer>, Integer>) value -> value.f0,
+			TypeInformation.of(Integer.class))
+			.map(new FailingMapperFunction(NUM_OF_RESTARTS))
+			.setParallelism(NUM_OF_REGIONS)
+			.addSink(new ValidatingSink())
+			.setParallelism(NUM_OF_REGIONS);
+
+		// another stream graph totally disconnected with the above one.
+		env.addSource(new StringGeneratingSourceFunction(NUM_ELEMENTS, NUM_ELEMENTS / NUM_OF_RESTARTS)).setParallelism(1)
+			.map((MapFunction<Tuple2<Integer, Integer>, Object>) value -> value).setParallelism(1);
+
+		return env.getStreamGraph().getJobGraph();
+	}
+
+	private static class StringGeneratingSourceFunction extends RichParallelSourceFunction<Tuple2<Integer, Integer>>
+		implements CheckpointListener, CheckpointedFunction {
+		private static final long serialVersionUID = 1L;
+
+		private final long numElements;
+		private final long checkpointLatestAt;
+
+		private int index = -1;
+
+		private int lastRegionIndex = -1;
+
+		private volatile boolean isRunning = true;
+
+		private ListState<Integer> listState;
+
+		private static final ListStateDescriptor<Integer> stateDescriptor = new ListStateDescriptor<>("list-1", Integer.class);
+
+		private ListState<Integer> unionListState;
+
+		private static final ListStateDescriptor<Integer> unionStateDescriptor = new ListStateDescriptor<>("list-2", Integer.class);
+
+		StringGeneratingSourceFunction(long numElements, long checkpointLatestAt) {
+			this.numElements = numElements;
+			this.checkpointLatestAt = checkpointLatestAt;
+		}
+
+		@Override
+		public void run(SourceContext<Tuple2<Integer, Integer>> ctx) throws Exception {
+			if (index < 0) {
+				// not been restored, so initialize
+				index = 0;
+			}
+
+			int subTaskIndex = getRuntimeContext().getIndexOfThisSubtask();
+			while (isRunning && index < numElements) {
+
+				synchronized (ctx.getCheckpointLock()) {
+					index += 1;
+					int key = index / 2;
+					int forwardTaskIndex = KeyGroupRangeAssignment.assignKeyToParallelOperator(key, MAX_PARALLELISM, NUM_OF_REGIONS);
+					// pre-partition output keys
+					if (forwardTaskIndex == subTaskIndex) {
+						// we would send data with the same key twice.
+						ctx.collect(Tuple2.of(key, index));
+					}
+				}
+
+				if (numCompletedCheckpoints.get() < 3) {
+					// not yet completed enough checkpoints, so slow down
+					if (index < checkpointLatestAt) {
+						// mild slow down
+						Thread.sleep(1);
+					} else {
+						// wait until the checkpoints are completed
+						while (isRunning && numCompletedCheckpoints.get() < 3) {
+							Thread.sleep(300);
+						}
+					}
+				}
+				if (jobFailedCnt.get() < NUM_OF_RESTARTS) {
+					// slow down if job has not failed for 'NUM_OF_RESTARTS' times.
+					Thread.sleep(1);
+				}
+			}
+		}
+
+		@Override
+		public void cancel() {
+			isRunning = false;
+		}
+
+		@Override
+		public void notifyCheckpointComplete(long checkpointId) {
+			if (getRuntimeContext().getIndexOfThisSubtask() == NUM_OF_REGIONS - 1) {
+				lastCompletedCheckpointId.set(checkpointId);
+				snapshotIndicesOfSubTask.put(checkpointId, lastRegionIndex);
+				numCompletedCheckpoints.incrementAndGet();
+			}
+		}
+
+		@Override
+		public void snapshotState(FunctionSnapshotContext context) throws Exception {
+			int indexOfThisSubtask = getRuntimeContext().getIndexOfThisSubtask();
+			if (indexOfThisSubtask != 0) {
+				listState.clear();
+				listState.add(index);
+				if (indexOfThisSubtask == NUM_OF_REGIONS - 1) {
+					lastRegionIndex = index;
+				}
+			}
+			unionListState.clear();
+			unionListState.add(indexOfThisSubtask);
+		}
+
+		@Override
+		public void initializeState(FunctionInitializationContext context) throws Exception {
+			int indexOfThisSubtask = getRuntimeContext().getIndexOfThisSubtask();
+			if (context.isRestored()) {
+				restoredState = true;
+
+				unionListState = context.getOperatorStateStore().getUnionListState(unionStateDescriptor);
+				Set<Integer> actualIndices = StreamSupport.stream(unionListState.get().spliterator(), false).collect(Collectors.toSet());
+				Assert.assertTrue(CollectionUtils.isEqualCollection(EXPECTED_INDICES, actualIndices));
+
+				if (indexOfThisSubtask == 0) {
+					listState = context.getOperatorStateStore().getListState(stateDescriptor);
+					Assert.assertTrue("list state should be empty for subtask-0",
+						((List<Integer>) listState.get()).isEmpty());
+				} else {
+					listState = context.getOperatorStateStore().getListState(stateDescriptor);
+					Assert.assertTrue("list state should not be empty for subtask-" + indexOfThisSubtask,
+						((List<Integer>) listState.get()).size() > 0);
+
+					if (indexOfThisSubtask == NUM_OF_REGIONS - 1) {
+						index = listState.get().iterator().next();
+						if (index != snapshotIndicesOfSubTask.get(lastCompletedCheckpointId.get())) {
+							throw new RuntimeException("Test failed due to unexpected recovered index: " + index +
+								", while last completed checkpoint record index: " + snapshotIndicesOfSubTask.get(lastCompletedCheckpointId.get()));
+						}
+					}
+				}
+			} else {
+				unionListState = context.getOperatorStateStore().getUnionListState(unionStateDescriptor);
+
+				if (indexOfThisSubtask != 0) {
+					listState = context.getOperatorStateStore().getListState(stateDescriptor);
+				}
+			}
+
+		}
+	}
+
+	private static class FailingMapperFunction extends RichMapFunction<Tuple2<Integer, Integer>, Tuple2<Integer, Integer>> {
+		private final int restartTimes;
+		private ValueState<Integer> valueState;
 
 Review comment:
   I'll send value as tuple of `<index/2, index>` from `StringGeneratingSourceFunction`, e.g. `1, 2` and `1, 3` would be emitted. `FailingMapperFunction` would then store keyed state `valueState` which tracks the maximum of value for the corresponding key, and emit `<key, max-value>` to `ValidatingSink`. In other words, we would have `1,3` finally in `ValidatingSink`'s `maps`. In `verifyAfterJobExecuted()` method, I'll then verify the `maps` in `ValidatingSink` works as expected to validate if key state has ever properly restored.

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