When Messages Are Published

To publish a message, a producer sends a record to the producer client library, which batches the records before sending them to the server. The producer client library will send the records to the server when any of the four following conditions are met.

  • The producer client library has batched enough messages to make an efficient RPC to the server.
  • A message has been queued for the amount of time that is specified for the streams.buffer.max.time.ms configuration parameter. For the Java client, the default interval for flushes is 3000 milliseconds. For clients based on librdkafka (for example, C and Python), the default interval for flushes is 0 (zero) milliseconds.
  • The producer client library has batched messages beyond the value of the buffer.memory configuration parameter.
  • The application explicitly flushes messages.
Tip: The default number of threads used for flushing messages is 64. In most cases, this number provides excellent performance. However, you can adjust this number by setting a value for the fs.mapr.threads parameter in the core-site.xml file on your client node.