How do I know if Kafka server is running?
I would say that another easy option to check if a Kafka server is running is to create a simple KafkaConsumer pointing to the cluste and try some action, for example, listTopics().
If kafka server is not running, you will get a TimeoutException and then you can use a try-catch sentence..
Does Kafka use RocksDB?
Kafka Streams supports fault-tolerant stateful applications. RocksDB is used by default to store state in such configurations. Apache Samza – Apache Samza offers similar functionality as Kafka Streams and it also uses RocksDB to store state in fault-tolerant configurations.
What happens when Kafka broker goes down?
Kafka does not create a new replica when a broker goes down. … If the offline broker was a follower, it will be marked a out of sync by the leader. When restarting the broker, it will try to get back in sync. Once done, whether it stays a follower or becomes the leader depends if it is the prefered replica.
How do you prevent duplicates in Kafka?
How do I get exactly-once messaging from Kafka?Use a single-writer per partition and every time you get a network error check the last message in that partition to see if your last write succeeded.Include a primary key (UUID or something) in the message and deduplicate on the consumer.
Can Kafka lost messages?
Kafka is speedy and fault-tolerant distributed streaming platform. However, there are some situations when messages can disappear. It can happen due to misconfiguration or misunderstanding Kafka’s internals.
How long does Kafka keep data?
The Kafka cluster retains all published messages—whether or not they have been consumed—for a configurable period of time. For example if the log retention is set to two days, then for the two days after a message is published it is available for consumption, after which it will be discarded to free up space.
How does Kafka store data?
Now you know how Kafka storage internals work:Partitions are Kafka’s storage unit.Partitions are split into segments.Segments are two files: its log and index.Indexes map each offset to their message’s position in the log, they’re used to look up messages.Indexes store offsets relative to its segment’s base offset.More items…•
Is Kafka exactly once?
Initially, Kafka only supported at-most-once and at-least-once message delivery. However, the introduction of Transactions between Kafka brokers and client applications ensures exactly-once delivery in Kafka.
Is Kafka at least once?
Introduction To Message Delivery Semantics In Kafka They are: At most once, at least once, exactly once. In at most once delivery, the message is either delivered or not delivered. This delivery semantic is suited for use cases where losing some messages do not affect the result of processing the complete data.