rkhachatryan commented on a change in pull request #16606: URL: https://github.com/apache/flink/pull/16606#discussion_r691587190
########## File path: flink-state-backends/flink-statebackend-changelog/src/main/java/org/apache/flink/state/changelog/materializer/PeriodicMaterializer.java ########## @@ -0,0 +1,263 @@ +/* + * 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.state.changelog.materializer; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.core.fs.FileSystemSafetyNet; +import org.apache.flink.runtime.checkpoint.CheckpointOptions; +import org.apache.flink.runtime.checkpoint.CheckpointType; +import org.apache.flink.runtime.mailbox.MailboxExecutor; +import org.apache.flink.runtime.state.CheckpointStorageLocationReference; +import org.apache.flink.runtime.state.CheckpointStorageWorkerView; +import org.apache.flink.runtime.state.CheckpointStreamFactory; +import org.apache.flink.runtime.state.KeyedStateHandle; +import org.apache.flink.runtime.state.SnapshotResult; +import org.apache.flink.runtime.state.Snapshotable; +import org.apache.flink.runtime.state.StateObject; +import org.apache.flink.runtime.state.changelog.ChangelogStateHandle; +import org.apache.flink.runtime.state.changelog.SequenceNumber; +import org.apache.flink.runtime.state.changelog.StateChangelogWriter; +import org.apache.flink.util.concurrent.ExecutorThreadFactory; +import org.apache.flink.util.concurrent.FutureUtils; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nonnull; + +import java.util.ArrayList; +import java.util.List; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.RunnableFuture; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicInteger; + +import static java.util.Collections.emptyList; +import static java.util.Collections.singletonList; +import static org.apache.flink.util.Preconditions.checkState; + +/** Periodically make materialization for the delegated state backend. */ +public class PeriodicMaterializer { + private static final Logger LOG = LoggerFactory.getLogger(PeriodicMaterializer.class); + + /** + * ChangelogStateBackend only supports CheckpointType.CHECKPOINT; The rest of information in + * CheckpointOptions is not used in Snapshotable#snapshot(). More details in FLINK-23441. + */ + private static final CheckpointOptions CHECKPOINT_OPTIONS = + new CheckpointOptions( + CheckpointType.CHECKPOINT, CheckpointStorageLocationReference.getDefault()); + + /** task mailbox executor, execute from Task Thread. */ + private final MailboxExecutor mailboxExecutor; + + /** Async thread pool, to complete async phase of materialization. */ + private final ExecutorService asyncOperationsThreadPool; + + /** scheduled executor, periodically trigger materialization. */ + private final ScheduledExecutorService periodicExecutor; + + private final CheckpointStreamFactory streamFactory; + + private final Snapshotable keyedStateBackend; + + private final StateChangelogWriter<ChangelogStateHandle> stateChangelogWriter; + + private final AsyncExceptionHandler asyncExceptionHandler; + + private final int allowedNumberOfFailures; + + /** Materialization failure retries. */ + private final AtomicInteger retries; + + /** Making sure only one materialization on going at a time. */ + private final AtomicBoolean materializationOnGoing; + + private long materializedId; + + private MaterializedState materializedState; + + public PeriodicMaterializer( + MailboxExecutor mailboxExecutor, + ExecutorService asyncOperationsThreadPool, + Snapshotable keyedStateBackend, + CheckpointStorageWorkerView checkpointStorageWorkerView, + StateChangelogWriter<ChangelogStateHandle> stateChangelogWriter, + AsyncExceptionHandler asyncExceptionHandler, + MaterializedState materializedState, + long periodicMaterializeInitDelay, + long periodicMaterializeInterval, + int allowedNumberOfFailures, + boolean materializationEnabled) { + this.mailboxExecutor = mailboxExecutor; + this.asyncOperationsThreadPool = asyncOperationsThreadPool; + this.keyedStateBackend = keyedStateBackend; + this.stateChangelogWriter = stateChangelogWriter; + this.asyncExceptionHandler = asyncExceptionHandler; + this.periodicExecutor = + Executors.newSingleThreadScheduledExecutor( + new ExecutorThreadFactory("periodic-materialization")); + this.streamFactory = shared -> checkpointStorageWorkerView.createTaskOwnedStateStream(); + this.allowedNumberOfFailures = allowedNumberOfFailures; + this.materializationOnGoing = new AtomicBoolean(false); + this.retries = new AtomicInteger(allowedNumberOfFailures); + + this.materializedId = 0; + this.materializedState = materializedState; + + if (materializationEnabled) { + this.periodicExecutor.scheduleAtFixedRate( + this::triggerMaterialization, + periodicMaterializeInitDelay, + periodicMaterializeInterval, + TimeUnit.MILLISECONDS); + } + } + + @VisibleForTesting + public void triggerMaterialization() { + mailboxExecutor.execute( + () -> { + // Only one materialization ongoing at a time + if (!materializationOnGoing.compareAndSet(false, true)) { + return; + } + + SequenceNumber upTo = stateChangelogWriter.lastAppendedSequenceNumber().next(); + + if (upTo.equals(materializedState.lastMaterializedTo())) { + return; + } + + RunnableFuture<SnapshotResult<KeyedStateHandle>> materializedRunnableFuture = + keyedStateBackend.snapshot( Review comment: Yes, I mean the sync phase. I think recoverable I/O failures are possible here, but I'm not sure if they should be tolerated TBH. For example: timeout writing to SAN/NAS, no disk space, file handle limit exceeded, bad sectors not handled by the FS. If it's too difficult to honour the limit here then failover is also an option. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
