Key Takeaways

1. Async/await helps with I/O, not CPU computation

   • I/O = waiting for external operations (files, network, database)
   • CPU = actively computing on the main thread

2. The event loop has 6 phases + microtasks

   • Microtasks (nextTick, Promises) run between every phase
   • Understanding this helps debug timing issues

3. For CPU-intensive tasks:

   • Use Worker Threads for true parallelism
   • Break up work with setImmediate for simpler cases
   • Never block the main thread

4. setImmediate always runs in the next loop iteration

   • Use it to give the event loop breathing room
   • Multiple calls in same loop run together in next iteration

5. Modern async patterns:

   • Use async/await for readability
   • Use Promise.all() for parallel operations
   • Always handle errors with try/catch