docs(concurrency): add detailed notes on Executors Framework in Java

WHAT was added:
- Comprehensive overview of Executors Framework (introduced in Java 5, part of java.util.concurrent).
- Clear explanation of WHY Executors are used:
  • Efficient thread pooling (reuse vs manual creation).
  • Reduced thread lifecycle overhead.
  • Built-in pooling strategies for different workloads.
  • Automatic handling of thread lifecycle.
- Key components highlighted:
  • Executor → base interface with execute(Runnable).
  • ExecutorService → advanced thread pool management (submit, shutdown, etc.).
  • Executors → factory class for creating various thread pools.
  • Future → async result handling.
- Detailed tables describing thread pool types:
  • FixedThreadPool → bounded concurrency.
  • CachedThreadPool → dynamic scaling, reuses idle threads.
  • SingleThreadExecutor → sequential task execution.
  • ScheduledThreadPool → supports delayed and periodic tasks.
- Advantages section included in two styles:
  • Bullet list with emojis (easy scan).
  • Extended explanation of performance, scalability, flexibility, and resource management.

WHY this matters:
- Provides a theoretical foundation for Java concurrency and thread pooling.
- Serves as a quick reference for choosing the right Executor type for different scenarios.
- Reinforces best practices (thread reuse > manual thread creation).

HINTS / NEXT STEPS:
- Always call shutdown() or shutdownNow() on ExecutorService to avoid resource leaks.
- FixedThreadPool → best for CPU-bound or predictable workloads.
- CachedThreadPool → good for many short-lived async tasks but avoid unbounded growth.
- SingleThreadExecutor → ensures task order and sequential execution.
- ScheduledThreadPool → preferred over Timer/TimerTask for recurring tasks.

KEYWORDS:
executors executorservice future threadpool concurrency scheduledthreadpool java-docs.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section19MultiThreading/ThreadPooling/src/Types Of Thread Pooling Executors Framework.txt renamed to Section19MultiThreading/ThreadPooling/ExecutorsFramework/src/TXTFiles/Types Of Thread Pooling Executors Framework.txt

@@ -48,4 +48,4 @@ Advantages of the Executors Framework
 ✔ Better Resource Management – Limits thread count to prevent excessive CPU and memory usage.
 ✔ Simplifies Thread Management – Eliminates the need for manual thread handling.
 ✔ Scalability – Adapts to workload demands efficiently.
-✔ Flexibility – Provides different thread pool strategies for various use cases.
+✔ Flexibility – Provides different thread pool strategies for various use cases.