📚 Main Topics

1. Types of Thread Pools in Java
   • Fixed Thread Pool
   • Cached Thread Pool
   • Scheduled Thread Pool
   • Single Threaded Executor

✨ Takeaways

• Fixed Thread Pool

  • Contains a fixed number of threads (e.g., 10 threads).
  • Tasks are submitted to a blocking queue, and threads fetch tasks sequentially.
  • Code example: Executors.newFixedThreadPool(size).

• Cached Thread Pool

  • Does not have a fixed number of threads; can create new threads as needed.
  • Uses a synchronous queue that holds only one task at a time.
  • Threads that are idle for more than 60 seconds are terminated to save resources.
  • Code example: Executors.newCachedThreadPool().

• Scheduled Thread Pool

  • Designed for tasks that need to be executed after a certain delay or at fixed intervals.
  • Uses a delay queue to manage task execution based on timing.
  • Supports three scheduling methods:
    1. Run a task after a specific delay.
    2. Run a task at a fixed rate.
    3. Run a task with a fixed delay after the previous task completes.
  • Code example: Executors.newScheduledThreadPool(size).

• Single Threaded Executor

  • Similar to a fixed thread pool but with only one thread.
  • Ensures that tasks are executed sequentially, maintaining the order of execution.
  • If the thread is killed due to an exception, it is recreated to continue processing tasks.
  • Code example: Executors.newSingleThreadExecutor().

🧠 Lessons

• Understanding the different types of thread pools helps in selecting the right one based on the application's concurrency requirements.
• Fixed thread pools are suitable for a known number of tasks, while cached thread pools are more flexible for varying workloads.
• Scheduled thread pools are essential for tasks that require timing control, such as periodic checks or delayed executions.
• Single-threaded executors are useful when task order is critical, ensuring that tasks are processed one at a time without overlap.