ExecutorService and Thread Pool types.

Why use it?

Decouples task submission from task execution. Manages a pool of threads instead of creating a new one for every task.

Types:

1. FixedThreadPool: Fixed number of threads.
2. CachedThreadPool: Creates new threads as needed, reuses idle ones.
3. SingleThreadExecutor: Exactly one thread.
4. ScheduledThreadPool: For delayed or periodic tasks.

Crucial Note:

Avoid using Executors.newCachedThreadPool() for high-load systems because it can create an unbounded number of threads, leading to OOM.