True Async I/O Comes to Zig: Coroutines Over Threads

Zig 0.16's std.Io abstraction provides a unified interface for async I/O, but its default thread-pool implementation struggles with high concurrency due to OS thread limits. The zio library demonstrates the real potential of true asynchronous I/O using platform-specific APIs like io_uring and kqueue, enabling efficient handling of tens of thousands of concurrent tasks—a capability essential for modern network servers. This separation of interface from implementation is a turning point for Zig, allowing developers to choose the async strategy that fits their workload.