Building a General-Purpose Thread Pool

Design the core components of a thread pool: a task queue and a set of worker threads.

Implement the worker thread's execution loop to safely fetch and execute tasks from the queue.

Implement the logic for submitting a new task to the thread pool's queue.

Use condition variables to efficiently manage worker threads (waking them for tasks and letting them sleep when idle).

Design a graceful shutdown mechanism that waits for all pending tasks to complete.

Implement the complete thread pool, including creation, task submission, and shutdown.