In Kotlin coroutine development, a common habit is to wrap every launch with Dispatchers.IO, assuming it makes code faster. However, this practice can introduce unnecessary overhead from thread context switching, especially for short-lived or CPU-bound tasks. The author shares their experience of gradually reducing Dispatchers.IO usage, noting that the default dispatcher is often sufficient for many operations. They emphasize that thread switching is not free and should be reserved for blocking I/O operations that genuinely need a separate thread pool. The post provides practical heuristics: use Dispatchers.IO for file or network I/O, but avoid it for simple computations or when the coroutine is already on a suitable thread. This perspective is crucial for developers building high-concurrency applications, as it encourages more deliberate dispatcher selection and better resource utilization.
A Kotlin developer explains why blindly adding Dispatchers.IO to every coroutine launch can degrade performance, and offers guidance on when to avoid explicit thread switching.