Node.js apps freeze under heavy I/O when the event loop is blocked. Use asynchronous I/O operations to keep the event loop responsive.

If your Node.js app freezes under heavy I/O, it’s likely due to blocking operations that prevent the event loop from processing other tasks. Node.js operates on a single-threaded event loop, so any blocking code, such as synchronous file or database operations, will cause the entire app to stall. To prevent this, ensure all I/O operations are asynchronous. For example, use fs.promises instead of fs.readFileSync() for file operations. For CPU-intensive tasks, you can offload work to worker threads or child processes to prevent blocking the event loop. Properly handling I/O ensures your app remains responsive even under heavy load.