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https://issues.apache.org/jira/browse/FLINK-35351?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17846241#comment-17846241
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Dmitriy Linevich commented on FLINK-35351:
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Hi [~pnowojski] ,
I am not suggesting to disallow rescaling, just that in our particular example
we change parallelism only for source and do not change sink. If we change
parallelism for both, there will be no problems with recovery.
I think the problem is not in the custom partitioner, but in
SubtaskStateMapper.FULL.
In the nearest future I will try to create a Pull Request, which will make the
proposed solution clearer.
> Restore from unaligned checkpoints with a custom partitioner fails.
> -------------------------------------------------------------------
>
> Key: FLINK-35351
> URL: https://issues.apache.org/jira/browse/FLINK-35351
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Checkpointing
> Reporter: Dmitriy Linevich
> Assignee: Dmitriy Linevich
> Priority: Major
>
> We encountered a problem when using a custom partitioner with unaligned
> checkpoints. The bug reproduces under the following steps:
> # Run a job with graph: Source[2]->Sink[3], the custom partitioner applied
> after the Source task.
> # Make a checkpoint.
> # Restore from the checkpoint with a different source parallelism:
> Source[1]->Sink[3].
> # An exception is thrown.
> This issue does not occur when restoring with the same parallelism or when
> changing the Sink parallelism. The exception only occurs when the parallelism
> of the Source is changed while the Sink parallelism remains the same.
> See the exception below and the test code at the end.
> {code:java}
> [db13789c52b80aad852c53a0afa26247] Task [Sink: sink (3/3)#0] WARN Sink: sink
> (3/3)#0
> (be1d158c2e77fc9ed9e3e5d9a8431dc2_0a448493b4782967b150582570326227_2_0)
> switched from RUNNING to FAILED with failure cause:
> java.io.IOException: Can't get next record for channel
> InputChannelInfo{gateIdx=0, inputChannelIdx=0}
> at
> org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.emitNext(AbstractStreamTaskNetworkInput.java:106)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:65)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:600)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:231)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:930)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:879)
> ~[classes/:?]
> at
> org.apache.flink.runtime.taskmanager.Task.runWithSystemExitMonitoring(Task.java:960)
> ~[classes/:?]
> at
> org.apache.flink.runtime.taskmanager.Task.restoreAndInvoke(Task.java:939)
> [classes/:?]
> at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:753)
> [classes/:?]
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:568)
> [classes/:?]
> at java.lang.Thread.run(Thread.java:745) [?:1.8.0_121]
> Caused by: java.io.IOException: Corrupt stream, found tag: -1
> at
> org.apache.flink.streaming.runtime.streamrecord.StreamElementSerializer.deserialize(StreamElementSerializer.java:222)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.streamrecord.StreamElementSerializer.deserialize(StreamElementSerializer.java:44)
> ~[classes/:?]
> at
> org.apache.flink.runtime.plugable.NonReusingDeserializationDelegate.read(NonReusingDeserializationDelegate.java:53)
> ~[classes/:?]
> at
> org.apache.flink.runtime.io.network.api.serialization.NonSpanningWrapper.readInto(NonSpanningWrapper.java:337)
> ~[classes/:?]
> at
> org.apache.flink.runtime.io.network.api.serialization.SpillingAdaptiveSpanningRecordDeserializer.readNonSpanningRecord(SpillingAdaptiveSpanningRecordDeserializer.java:128)
> ~[classes/:?]
> at
> org.apache.flink.runtime.io.network.api.serialization.SpillingAdaptiveSpanningRecordDeserializer.readNextRecord(SpillingAdaptiveSpanningRecordDeserializer.java:103)
> ~[classes/:?]
> at
> org.apache.flink.runtime.io.network.api.serialization.SpillingAdaptiveSpanningRecordDeserializer.getNextRecord(SpillingAdaptiveSpanningRecordDeserializer.java:93)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.io.recovery.DemultiplexingRecordDeserializer$VirtualChannel.getNextRecord(DemultiplexingRecordDeserializer.java:79)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.io.recovery.DemultiplexingRecordDeserializer.getNextRecord(DemultiplexingRecordDeserializer.java:154)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.io.recovery.DemultiplexingRecordDeserializer.getNextRecord(DemultiplexingRecordDeserializer.java:54)
> ~[classes/:?]
> at
> org.apache.flink.streaming.runtime.io.AbstractStreamTaskNetworkInput.emitNext(AbstractStreamTaskNetworkInput.java:103)
> ~[classes/:?]
> ... 10 more {code}
> We discovered that this issue occurs due to an optimization in the
> [StateAssignmentOperation::reDistributeInputChannelStates|https://github.com/apache/flink/blame/master/flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/StateAssignmentOperation.java#L424]
> {code:java}
> if (inputState.getParallelism() ==
> executionJobVertex.getParallelism()) {
> stateAssignment.inputChannelStates.putAll(
> toInstanceMap(stateAssignment.inputOperatorID,
> inputOperatorState));
> return;
> }
> {code}
> At the moment of checkpointing, some in-flight records could be partially
> sent. The Sink sub-task's input has one half of a record, and the Source
> sub-task's output has the second part of the record. When restoring in-flight
> data, all the records are sent from all Source sub-tasks to all Sink
> sub-tasks. However, due to the optimization mentioned above, some Sink
> sub-tasks might not have information about the beginnings of in-flight
> records.
> The proposed fix involves checking the situations when the optimization
> should not be applied:
> {code:java}
> boolean noNeedRescale = stateAssignment.executionJobVertex
> .getJobVertex()
> .getInputs()
> .stream()
> .map(JobEdge::getDownstreamSubtaskStateMapper)
> .anyMatch(m -> !m.equals(SubtaskStateMapper.FULL))
> && stateAssignment.executionJobVertex
> .getInputs()
> .stream()
> .map(IntermediateResult::getProducer)
> .map(vertexAssignments::get)
> .anyMatch(taskStateAssignment -> {
> final int oldParallelism =
>
> stateAssignment.oldState.get(stateAssignment.inputOperatorID).getParallelism();
> return oldParallelism ==
> taskStateAssignment.executionJobVertex.getParallelism();
> });
> if (inputState.getParallelism() == executionJobVertex.getParallelism() &&
> noNeedRescale) {code}
>
> Test for reproduce:
> {code:java}
> package org.apache.flink.test.checkpointing;
> import org.apache.flink.api.common.JobID;
> import org.apache.flink.api.common.JobStatus;
> import org.apache.flink.api.common.functions.Partitioner;
> import org.apache.flink.configuration.Configuration;
> import org.apache.flink.core.fs.Path;
> import org.apache.flink.runtime.jobgraph.JobGraph;
> import org.apache.flink.runtime.jobgraph.SavepointRestoreSettings;
> import org.apache.flink.runtime.minicluster.MiniCluster;
> import org.apache.flink.runtime.minicluster.MiniClusterConfiguration;
> import org.apache.flink.streaming.api.environment.CheckpointConfig;
> import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
> import org.apache.flink.streaming.api.functions.sink.SinkFunction;
> import org.apache.flink.streaming.api.functions.source.ParallelSourceFunction;
> import org.apache.flink.util.FileUtils;
> import org.junit.After;
> import org.junit.Rule;
> import org.junit.Test;
> import org.junit.rules.TemporaryFolder;
> import java.io.File;
> import static
> org.apache.flink.streaming.api.environment.StreamExecutionEnvironment.createLocalEnvironmentWithWebUI;
> import static org.junit.Assert.fail;
> /** Integration test for performing rescale of unaligned checkpoint with
> custom partitioner. */
> public class UnalignedCheckpointCustomRescaleITCase {
> @Rule
> public TemporaryFolder tempFolder = new TemporaryFolder();
> private final static File CHECKPOINT_FILE = new
> File("src/test/resources/custom-checkpoint");
> @Test
> public void createCheckpoint() {
> runJob(2, 3, true);
> }
> @Test
> public void restoreFromCheckpoint() {
> runJob(1, 3, false);
> }
> @After
> public void after() {
> tempFolder.delete();
> }
> private void runJob(int sourceParallelism, int sinkParallelism, boolean
> createCheckpoint) {
> try (MiniCluster miniCluster = new
> MiniCluster(buildMiniClusterConfig())) {
> miniCluster.start();
> Configuration configuration = new Configuration();
> StreamExecutionEnvironment env =
> createLocalEnvironmentWithWebUI(configuration);
> CheckpointConfig checkpointConfig = env.getCheckpointConfig();
> env.enableCheckpointing(Integer.MAX_VALUE);
> checkpointConfig.setForceUnalignedCheckpoints(true);
> checkpointConfig.enableUnalignedCheckpoints();
> checkpointConfig.setMaxConcurrentCheckpoints(1);
>
> checkpointConfig.setExternalizedCheckpointCleanup(CheckpointConfig.ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION);
> checkpointConfig.setCheckpointStorage("file://" +
> tempFolder.newFolder() + "/checkPoints");
> env
> .addSource(new StringsSource(createCheckpoint ? 10 : 0,
> sinkParallelism))
> .name("source")
> .setParallelism(sourceParallelism)
> .partitionCustom(new StringPartitioner(), str ->
> str.split(" ")[0])
> .addSink(new StringSink(createCheckpoint ? 16 : 100000))
> .name("sink")
> .setParallelism(sinkParallelism);
> JobGraph job = env.getStreamGraph().getJobGraph();
> if (!createCheckpoint) {
>
> job.setSavepointRestoreSettings(SavepointRestoreSettings.forPath("file://" +
> CHECKPOINT_FILE.getAbsolutePath(), false));
> }
> JobID jobId = miniCluster.submitJob(job).get().getJobID();
> if (createCheckpoint) {
> while
> (!miniCluster.getJobStatus(jobId).get().equals(JobStatus.RUNNING)) {
> Thread.sleep(1000);
> }
> String savepointPath =
> miniCluster.triggerCheckpoint(jobId).get();
> System.out.println("SAVE PATH " + savepointPath);
> Thread.sleep(1000);
> miniCluster.cancelJob(jobId);
> FileUtils.copy(new Path(savepointPath),
> Path.fromLocalFile(CHECKPOINT_FILE), false);
> } else {
> int count = 0;
> while
> (!miniCluster.getJobStatus(jobId).get().equals(JobStatus.RUNNING)) {
> Thread.sleep(1000);
> count++;
> if (count > 10) {
> break;
> }
> }
> Thread.sleep(10000);
> boolean fail =
> !miniCluster.getJobStatus(jobId).get().equals(JobStatus.RUNNING);
> miniCluster.cancelJob(jobId);
> if (fail) {
> fail("Job fails");
> }
> }
> } catch (Exception e) {
> throw new RuntimeException(e);
> }
> }
> private static MiniClusterConfiguration buildMiniClusterConfig() {
> return new MiniClusterConfiguration.Builder()
> .setNumTaskManagers(2)
> .setNumSlotsPerTaskManager(4)
> .build();
> }
> private static class StringsSource implements
> ParallelSourceFunction<String> {
> volatile boolean isCanceled;
> final int producePerPartition;
> final int partitionCount;
> public StringsSource(int producePerPartition, int partitionCount) {
> this.producePerPartition = producePerPartition;
> this.partitionCount = partitionCount;
> }
> private String buildString(int partition, int index) {
> String longStr = new String(new char[3713]).replace('\0',
> '\uFFFF');
> return partition + " " + index + " " + longStr;
> }
> @Override
> public void run(SourceContext<String> ctx) throws Exception {
> for (int i = 0; i < producePerPartition; i++) {
> for (int partition = 0; partition < partitionCount;
> partition++) {
> ctx.collect(buildString(partition, i));
> }
> }
> while (!isCanceled) { Thread.sleep(1000); }
> }
> @Override
> public void cancel() { isCanceled = true; }
> }
> private static class StringSink implements SinkFunction<String> {
> final int consumeBeforeCheckpoint;
> int consumed = 0;
> public StringSink(int consumeBeforeCheckpoint) {
> this.consumeBeforeCheckpoint = consumeBeforeCheckpoint;
> }
> @Override
> public void invoke(String value, Context ctx) throws
> InterruptedException {
> consumed++;
> System.out.println("--- CONSUMED --- " + value.substring(0, 10));
> if (consumed == consumeBeforeCheckpoint) {
> System.out.println("--- WAITING FOR CHECKPOINT START ---");
> Thread.sleep(4000);
> }
> }
> }
> public static class StringPartitioner implements Partitioner<String> {
> @Override
> public int partition(String key, int numPartitions) {
> return Integer.parseInt(key) % numPartitions;
> }
> }
> }
> {code}
>
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