1.
Handling Failure with
Grace
Stream’s uncaught exception handler
Walker Carlson
wcarlson@confluent.io

2.
KIPs 663, 671 and 696
• KIP-663 - Threading model moves to be more dynamic
• KIP-671 - Introduce a new handler to prevent issues we have seen in the past
• KIP-696 - Changed the state machine

3.
ERROR state
Same as NOT_RUNNING but triggered by an expectation instead of a close call.
CREATED
RUNNING
RE-
BALANCING
PENDING
SHUTDOWN
PENDING
ERROR
NOT
RUNNING
ERROR

4.
Old Handler
• Uses the Java runtime handler behind the scenes
• Kills the thread
• Cascading thread death is possible if not aware
• Is deprecated and will be removed soon

5.
New Handler
• User code returns an ENUM to choose behavior after notification logic is done
• Takes advantage of the threading model to make a thread replacement algorithm
• Gives more flexibility
• Does not do anything new with global threads

6.
Shutdown Client
• Closest to the old behavior
• Close the client to ERROR state instead of one thread at a time

7.
Shutdown Application
• Uses the rebalance protocall to try to shutdown all clients of the application
• May fail if a different client is not in the group
• Fastest/only internal way to stop all clients

8.
Replace Thread
• New thread is brought up with new ID
• Rebalances
• Works with static membership
• Not always a good idea