How the commit request severed by kafka internally?

when a Offsetcommit request thrown from a consumer how the kafka broker handle it internally?
which are the threads are responsible to the offset commit request?

>Solution :

1.All request messages (including OffsetCommit request) first arrive in the network queue.
2. And then go to the request queue (in kafka broker)by the network_thread.
3.Then IO thread process it and it go to the purgatory and then send to response queue.
4.Finally network thread send the response to the client.