python_syntax_concurrent_futures_ThreadPoolExecutor

gistfile1.txt

import concurrent.futures
import time

def background_task(task_id):
  item_list = []
  for i in range(3):
    item_list.append((task_id, i))
    time.sleep(1)
  return item_list

def task_done_callback(future):
  try:
    result = future.result()
    print("Background task completed with result:", result)
  except Exception as e:
    print("Background task raised an exception:", e)

def main():
  tasks = []
  # With ThreadPoolExecutor, you can control pool size
  with concurrent.futures.ThreadPoolExecutor(max_workers=10) as executor:
    for i in range(3):  # Submitting 3 background tasks
      future = executor.submit(background_task, i)
      future.add_done_callback(task_done_callback)
      tasks.append(future)

    print("Main thread continues execution while background tasks are running...")

  print("Waiting for background tasks to complete...")
  for task in tasks:
    try:
      task.result()  # This will wait for each task to complete. This will re-raise any exception caught during the task execution.
    except Exception as task_err:
      print(f"{task_err}")

if __name__ == "__main__":
  main()