When deciding between creating a separate publisher thread per topic versus having a single publisher handle multiple topics in Kafka, there are several factors to consider:

Throughput and Performance:
Separate Publisher Threads: This approach can potentially increase throughput as each thread can independently handle the publishing to its respective topic. This can be beneficial if you have high message rates and need to maximize performance. Single Publisher: Managing multiple topics with a single publisher can simplify the design and reduce resource usage. However, it might become a bottleneck if the message rate is high.

Resource Management:
Separate Publisher Threads: More threads mean more resource consumption (CPU, memory). This can lead to increased complexity in managing these resources. Single Publisher: Easier to manage resources as you have fewer threads. This can be more efficient in environments with limited resources.

Complexity:
Separate Publisher Threads: Increases the complexity of your application. You need to manage multiple threads, handle synchronization, and ensure thread safety. Single Publisher: Simpler design and easier to maintain. You only need to manage one thread, which can reduce the potential for bugs and synchronization issues. Fault Tolerance and Reliability:
Separate Publisher Threads: If one thread fails, it only affects the topic it is responsible for. Other topics can continue to be published without interruption. Single Publisher: If the single publisher thread fails, it can affect all topics being published. This can be mitigated with proper error handling and retry mechanisms.

Recommendation For a beginner, starting with a single publisher handling multiple topics might be easier to implement and manage. As you gain more experience and if you encounter performance bottlenecks, you can consider moving to a model with separate publisher threads per topic.