[Enhancement] Optimize time complexity of loop in ConsumerGroupInfo#updateSubscription method

[drpmma]

Before Creating the Enhancement Request

• I have confirmed that this should be classified as an enhancement rather than a bug/feature.

Summary

The current implementation of the updateSubscription method in the code has a potential issue with the time complexity of the loop. The loop iterates over the subscription table to check if a topic exists in the subscription list. This results in a time complexity of O(n) for each iteration.

Motivation

Optimize performance for a large scale of subscriptions.

Describe the Solution You'd Like

To optimize the time complexity, we can introduce an additional HashSet to store the new topics. By doing so, we can perform a constant time (O(1)) lookup instead of iterating over the subscription table in the loop. This will significantly reduce the time complexity of the loop.

Describe Alternatives You've Considered

No

Additional Context

No response