Kafka Streaming Concurrency? : <p>I have some basic Kafka Streaming code that reads records from one topic, does some processing, and outputs records to another topic.</p>

<p>How does Kafka streaming handle concurrency? Is everything run in a single thread? I don't see this mentioned in the documentation.</p>

<p>If it's single threaded, I would like options for multi-threaded processing to handle high volumes of data.</p>

<p>If it's multi-threaded, I need to understand how this works and how to handle resources, like SQL database connections should be shared in different processing threads.</p>

<p>Is Kafka's built-in streaming API not recommended for high volume scenarios relative to other options (Spark, Akka, Samza, Storm, etc)?</p>
