Why can it take so long to delete Kafka topics?

Question

On a 3 node cluster, I created few topics with thousands of messages. I have noticed that it takes long time to delete a topic. It took me more than 14 mins to delete 500 topics.

1. Are there any best practices for topic deletion?
2. Is there any document that explains why it takes so much time to delete a topic ?
3. When I create a topic, Kafka will create a folder under log.dirs. I had 10000 topics; I ran a command to delete all of them. Kafka has deleted all 10000 files from log.dirs but Kafka-topics.sh shows topics that does not exist on the file system with "- marked for deletion".

Answer 1

Kafka topic deletion is not guaranteed to be instant. When you 'delete' a topic, you are actually marking it for deletion. When the TopicDeletionManager next runs, it will then start removing any topics that are marked for deletion. This may also take longer if the topic logs are larger.