A Guide to Exception Handling in Kotlin Coroutines

Kotlin coroutines follow the Structured Concurrency principle, in which parent and child coroutines share a systematic lifecycle. In this process, when an exception occurs in a child coroutine, that exception propagates to the parent coroutine, and if not handled properly, the entire coroutine hierarchy can be canceled, potentially destabilizing the system.

The basic behavior of exception propagation and cancellation is as follows:

• Exception occurs: Both the coroutine and its child coroutines are all canceled
• Exception propagation: The exception is passed to the parent coroutine, causing the parent coroutine to be canceled as well
• Entire hierarchy canceled: When the parent is canceled, all other child coroutines are canceled together

To maintain system stability, appropriate exception handling methods must be applied depending on the situation. Key methods include setting a CoroutineExceptionHandler, blocking exception propagation using SupervisorJob or supervisorScope, and breaking the parent-child relationship using Job.