Examples with WatermarkTracker org.apache.flink.streaming.connectors.kinesis.util.WatermarkTracker used on opensource projects

Example 1 with WatermarkTracker

use of org.apache.flink.streaming.connectors.kinesis.util.WatermarkTracker in project flink by apache.

the class KinesisDataFetcher method runFetcher.

/**
 * Starts the fetcher. After starting the fetcher, it can only be stopped by calling {@link
 * KinesisDataFetcher#shutdownFetcher()}.
 *
 * @throws Exception the first error or exception thrown by the fetcher or any of the threads
 *     created by the fetcher.
 */
public void runFetcher() throws Exception {
    // check that we are running before proceeding
    if (!running) {
        return;
    }
    // ------------------------------------------------------------------------
    // Procedures before starting the infinite while loop:
    // ------------------------------------------------------------------------
    // 1. check that there is at least one shard in the subscribed streams to consume from (can
    // be done by
    // checking if at least one value in subscribedStreamsToLastDiscoveredShardIds is not
    // null)
    boolean hasShards = false;
    StringBuilder streamsWithNoShardsFound = new StringBuilder();
    for (Map.Entry<String, String> streamToLastDiscoveredShardEntry : subscribedStreamsToLastDiscoveredShardIds.entrySet()) {
        if (streamToLastDiscoveredShardEntry.getValue() != null) {
            hasShards = true;
        } else {
            streamsWithNoShardsFound.append(streamToLastDiscoveredShardEntry.getKey()).append(", ");
        }
    }
    if (streamsWithNoShardsFound.length() != 0 && LOG.isWarnEnabled()) {
        LOG.warn("Subtask {} has failed to find any shards for the following subscribed streams: {}", indexOfThisConsumerSubtask, streamsWithNoShardsFound.toString());
    }
    if (!hasShards) {
        throw new RuntimeException("No shards can be found for all subscribed streams: " + streams);
    }
    // consumer using a restored state checkpoint
    for (int seededStateIndex = 0; seededStateIndex < subscribedShardsState.size(); seededStateIndex++) {
        KinesisStreamShardState seededShardState = subscribedShardsState.get(seededStateIndex);
        // read already
        if (!seededShardState.getLastProcessedSequenceNum().equals(SentinelSequenceNumber.SENTINEL_SHARD_ENDING_SEQUENCE_NUM.get())) {
            if (LOG.isInfoEnabled()) {
                LOG.info("Subtask {} will start consuming seeded shard {} from sequence number {} with ShardConsumer {}", indexOfThisConsumerSubtask, seededShardState.getStreamShardHandle().toString(), seededShardState.getLastProcessedSequenceNum(), seededStateIndex);
            }
            StreamShardHandle streamShardHandle = subscribedShardsState.get(seededStateIndex).getStreamShardHandle();
            KinesisDeserializationSchema<T> shardDeserializationSchema = getClonedDeserializationSchema();
            shardDeserializationSchema.open(RuntimeContextInitializationContextAdapters.deserializationAdapter(runtimeContext, // ignore the provided metric group
            metricGroup -> consumerMetricGroup.addGroup("subtaskId", String.valueOf(indexOfThisConsumerSubtask)).addGroup("shardId", streamShardHandle.getShard().getShardId()).addGroup("user")));
            shardConsumersExecutor.submit(createShardConsumer(seededStateIndex, streamShardHandle, subscribedShardsState.get(seededStateIndex).getLastProcessedSequenceNum(), registerShardMetricGroup(consumerMetricGroup, subscribedShardsState.get(seededStateIndex)), shardDeserializationSchema));
        }
    }
    // start periodic watermark emitter, if a watermark assigner was configured
    if (periodicWatermarkAssigner != null) {
        long periodicWatermarkIntervalMillis = runtimeContext.getExecutionConfig().getAutoWatermarkInterval();
        if (periodicWatermarkIntervalMillis > 0) {
            ProcessingTimeService timerService = ((StreamingRuntimeContext) runtimeContext).getProcessingTimeService();
            LOG.info("Starting periodic watermark emitter with interval {}", periodicWatermarkIntervalMillis);
            new PeriodicWatermarkEmitter(timerService, periodicWatermarkIntervalMillis).start();
            if (watermarkTracker != null) {
                // setup global watermark tracking
                long watermarkSyncMillis = Long.parseLong(getConsumerConfiguration().getProperty(ConsumerConfigConstants.WATERMARK_SYNC_MILLIS, Long.toString(ConsumerConfigConstants.DEFAULT_WATERMARK_SYNC_MILLIS)));
                watermarkTracker.setUpdateTimeoutMillis(// synchronization latency
                watermarkSyncMillis * 3);
                watermarkTracker.open(runtimeContext);
                new WatermarkSyncCallback(timerService, watermarkSyncMillis).start();
                // emit records ahead of watermark to offset synchronization latency
                long lookaheadMillis = Long.parseLong(getConsumerConfiguration().getProperty(ConsumerConfigConstants.WATERMARK_LOOKAHEAD_MILLIS, Long.toString(0)));
                recordEmitter.setMaxLookaheadMillis(Math.max(lookaheadMillis, watermarkSyncMillis * 3));
                // record emitter depends on periodic watermark
                // it runs in a separate thread since main thread is used for discovery
                Runnable recordEmitterRunnable = new Runnable() {

                    @Override
                    public void run() {
                        try {
                            recordEmitter.run();
                        } catch (Throwable error) {
                            // report the error that terminated the emitter loop to
                            // source thread
                            stopWithError(error);
                        }
                    }
                };
                Thread thread = new Thread(recordEmitterRunnable);
                thread.setName("recordEmitter-" + runtimeContext.getTaskNameWithSubtasks());
                thread.setDaemon(true);
                thread.start();
            }
        }
        this.shardIdleIntervalMillis = Long.parseLong(getConsumerConfiguration().getProperty(ConsumerConfigConstants.SHARD_IDLE_INTERVAL_MILLIS, Long.toString(ConsumerConfigConstants.DEFAULT_SHARD_IDLE_INTERVAL_MILLIS)));
    }
    // ------------------------------------------------------------------------
    // finally, start the infinite shard discovery and consumer launching loop;
    // we will escape from this loop only when shutdownFetcher() or stopWithError() is called
    // TODO: have this thread emit the records for tracking backpressure
    final long discoveryIntervalMillis = Long.parseLong(configProps.getProperty(ConsumerConfigConstants.SHARD_DISCOVERY_INTERVAL_MILLIS, Long.toString(ConsumerConfigConstants.DEFAULT_SHARD_DISCOVERY_INTERVAL_MILLIS)));
    if (this.numberOfActiveShards.get() == 0) {
        LOG.info("Subtask {} has no active shards to read on startup; marking the subtask as temporarily idle ...", indexOfThisConsumerSubtask);
        sourceContext.markAsTemporarilyIdle();
    }
    while (running) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Subtask {} is trying to discover new shards that were created due to resharding ...", indexOfThisConsumerSubtask);
        }
        List<StreamShardHandle> newShardsDueToResharding = discoverNewShardsToSubscribe();
        for (StreamShardHandle shard : newShardsDueToResharding) {
            // since there may be delay in discovering a new shard, all new shards due to
            // resharding should be read starting from the earliest record possible
            KinesisStreamShardState newShardState = new KinesisStreamShardState(convertToStreamShardMetadata(shard), shard, SentinelSequenceNumber.SENTINEL_EARLIEST_SEQUENCE_NUM.get());
            int newStateIndex = registerNewSubscribedShardState(newShardState);
            if (LOG.isInfoEnabled()) {
                LOG.info("Subtask {} has discovered a new shard {} due to resharding, and will start consuming " + "the shard from sequence number {} with ShardConsumer {}", indexOfThisConsumerSubtask, newShardState.getStreamShardHandle().toString(), newShardState.getLastProcessedSequenceNum(), newStateIndex);
            }
            StreamShardHandle streamShardHandle = newShardState.getStreamShardHandle();
            KinesisDeserializationSchema<T> shardDeserializationSchema = getClonedDeserializationSchema();
            shardDeserializationSchema.open(RuntimeContextInitializationContextAdapters.deserializationAdapter(runtimeContext, // ignore the provided metric group
            metricGroup -> consumerMetricGroup.addGroup("subtaskId", String.valueOf(indexOfThisConsumerSubtask)).addGroup("shardId", streamShardHandle.getShard().getShardId()).addGroup("user")));
            shardConsumersExecutor.submit(createShardConsumer(newStateIndex, newShardState.getStreamShardHandle(), newShardState.getLastProcessedSequenceNum(), registerShardMetricGroup(consumerMetricGroup, newShardState), shardDeserializationSchema));
        }
        // interval if the running flag was set to false during the middle of the while loop
        if (running && discoveryIntervalMillis != 0) {
            try {
                cancelFuture.get(discoveryIntervalMillis, TimeUnit.MILLISECONDS);
                LOG.debug("Cancelled discovery");
            } catch (TimeoutException iex) {
            // timeout is expected when fetcher is not cancelled
            }
        }
    }
    // make sure all resources have been terminated before leaving
    try {
        awaitTermination();
    } catch (InterruptedException ie) {
        // If there is an original exception, preserve it, since that's more important/useful.
        this.error.compareAndSet(null, ie);
    }
    // any error thrown in the shard consumer threads will be thrown to the main thread
    Throwable throwable = this.error.get();
    if (throwable != null) {
        if (throwable instanceof Exception) {
            throw (Exception) throwable;
        } else if (throwable instanceof Error) {
            throw (Error) throwable;
        } else {
            throw new Exception(throwable);
        }
    }
}