Why Does Kafka Fail to Receive the Data Written Back by Spark Streaming?

Question

While a running Spark Streaming task is writing data back to Kafka, Kafka cannot receive the written data and Kafka logs contain the following error information:

2016-03-02 17:46:19,017 | INFO | [kafka-network-thread-21005-1] | Closing socket connection to /10.91.8.208 due to invalid request: Request of length
 122371301 is not valid, it is larger than the maximum size of 104857600 bytes. | kafka.network.Processor (Logging.scala:68)
2016-03-02 17:46:19,155 | INFO | [kafka-network-thread-21005-2] | Closing socket connection to /10.91.8.208. | kafka.network.Processor (Logging.scala:68)
2016-03-02 17:46:19,270 | INFO | [kafka-network-thread-21005-0] | Closing socket connection to /10.91.8.208 due to invalid request: 
Request of length 122371301 is not valid, it is larger than the maximum size of 104857600 bytes. | kafka.network.Processor (Logging.scala:68)
2016-03-02 17:46:19,513 | INFO | [kafka-network-thread-21005-1] | Closing socket connection to /10.91.8.208 due to invalid request: 
Request of length 122371301 is not valid, it is larger than the maximum size of 104857600 bytes. | kafka.network.Processor (Logging.scala:68)
2016-03-02 17:46:19,763 | INFO | [kafka-network-thread-21005-2] | Closing socket connection to /10.91.8.208 due to invalid request: 
Request of length 122371301 is not valid, it is larger than the maximum size of 104857600 bytes. | kafka.network.Processor (Logging.scala:68)
53393 [main] INFO  org.apache.hadoop.mapreduce.Job  - Counters: 50

Answer

As shown in the figure below, the logic defined in Spark Streaming applications is as follows: reading data from Kafka -> executing processing -> writing result data back to Kafka.

Imagine that data is written into Kafka at a data rate of 10 MB/s, the interval (defined in Spark Streaming) between write-back operations is 60s, and a total of 600-MB data needs to be written back into Kafka. If Kafka defines that a maximum of 500-MB data can be received at a time, then the size of written-back data exceeds the threshold, triggering the error information.

Figure 1 Application scenario

Solution:

• Method 1: On Spark Streaming, reduce the interval between write-back operations to avoid the size of written-back data exceeding the threshold defined by Kafka. The recommended interval is 5-10 seconds.
• Method 2: Increase the threshold defined in Kafka. It is advisable to increase the threshold by adjusting the socket.request.max.bytes parameter of Kafka service on FusionInsight Manager.