Spark Structured Streaming Kafka Offset Management

Question

I'm looking into storing kafka offsets inside of kafka for Spark Structured Streaming, like it's working for DStreams stream.asInstanceOf[CanCommitOffsets].commitAsync(offsetRanges), the same I'm looking but for Structured Streaming. Is it supporting for structured streaming ? If yes, how can I achieve it ?

I know about hdfs checkpointing using .option("checkpointLocation", checkpointLocation), but I'm interested exactly for built-in offset management.

I'm expecting kafka to store offsets only inside without spark hdfs checkpoint.

Jkulkarni Jkulkarni · Accepted Answer · 2019-06-13T02:50:14

I am using this piece of code found somewhere.

public class OffsetManager {

    private String storagePrefix;

    public OffsetManager(String storagePrefix) {
        this.storagePrefix = storagePrefix;
    }

    /**
     * Overwrite the offset for the topic in an external storage.
     *
     * @param topic     - Topic name.
     * @param partition - Partition of the topic.
     * @param offset    - offset to be stored.
     */
    void saveOffsetInExternalStore(String topic, int partition, long offset) {

        try {

            FileWriter writer = new FileWriter(storageName(topic, partition), false);

            BufferedWriter bufferedWriter = new BufferedWriter(writer);
            bufferedWriter.write(offset + "");
            bufferedWriter.flush();
            bufferedWriter.close();

        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }

    /**
     * @return he last offset + 1 for the provided topic and partition.
     */
    long readOffsetFromExternalStore(String topic, int partition) {

        try {

            Stream<String> stream = Files.lines(Paths.get(storageName(topic, partition)));

            return Long.parseLong(stream.collect(Collectors.toList()).get(0)) + 1;

        } catch (Exception e) {
            e.printStackTrace();
        }

        return 0;
    }

    private String storageName(String topic, int partition) {
        return "Offsets\\" + storagePrefix + "-" + topic + "-" + partition;
    }

}

SaveOffset...is called after the record processing is successful otherwise no offset is stored. and I am using Kafka topics as source so I specify the startingoffsets as the retrieved offsets from ReadOffsets...

Spark Structured Streaming Kafka Offset Management

2 Answers