Running Python Functions in the Background with Multithreading

How Can We Run a Process in the Background Without Blocking the Main Thread in Python?

What You’ll Learn

In this guide, you’ll learn how to use multithreading in Python to execute processes in the background without affecting the performance of the main thread.

Introduction to Problem and Solution

In scenarios where long-running tasks need to be performed without causing delays in the main application flow, such as in GUI applications or web servers, employing multithreading can be highly beneficial. Multithreading enables multiple threads (mini-processes) to run simultaneously within a single process space. By dedicating one thread to handle intensive tasks while keeping the main thread free for other operations, applications can remain responsive and efficient.


import threading

def background_task():
    print("Running background task...")
    # Your long-running task here.

# Create a Thread object targeting your function.
background_thread = threading.Thread(target=background_task)

# Start running the thread.

print("Main thread continues to run without blocking.")

# Copyright PHD


The provided solution showcases how to initiate a non-blocking operation using Python’s threading module:

  1. Importing Necessary Modules: The threading module is imported to facilitate thread creation and management.
  2. Defining Our Task: The background_task function represents the long-running operation that should not block the main program flow.
  3. Creating a Thread Object: A Thread instance (background_thread) is created with background_task as its target, enabling independent execution.
  4. Starting The Thread: Executing .start() on the Thread instance initiates its parallel execution alongside the main program flow.

This approach allows both tasks�inside background_task() and those on the main thread�to run concurrently without interference.

Deep Dive into Multithreading Explanation

Here’s a breakdown of how multithreading works:

Step Description
1 Import necessary modules (threading).
2 Define a function (background_task) for lengthy operations.
3 Create a Thread object with background_task as its target function (background_thread).
4 Start executing the background task using .start().
    1. How does multithreading differ from multiprocessing?

      • Multithreading involves concurrent execution within a single process by sharing memory space, whereas multiprocessing runs separate memory spaces across multiple processes.
    2. When should I use multithreading?

      • It’s ideal for IO-bound tasks where operations wait for external responses like file and network operations.
    3. Is python’s GIL an issue when using multithreading?

      • For CPU-bound tasks requiring heavy computation, yes; it hinders true parallelism due to bytecode execution serialization. However, it’s generally not an issue for IO-bound tasks.
    4. How do I pass arguments to my threaded function?

      • Use the args parameter when creating your Thread: e.g., Thread(target=my_function, args=(arg1,arg2)).
    5. Can threads share variables?

      • Yes, threads share variables since they exist in shared memory space within their parent process�but caution is needed regarding synchronization issues like deadlocks or race conditions.
    6. How do I make my threaded function return something?

      • Threads cannot directly return values; consider using shared data structures like queues or wrapping threaded functions inside classes that store results as attributes.
    7. What is daemon mode in threading?

      • Daemon threads are terminated once all non-daemon threads finish executing�an excellent choice for background tasks that shouldn’t delay program exit.

By effectively utilizing Python�s threading module as illustrated above, you can enhance your application�s responsiveness and speed even during prolonged operations by seamlessly integrating them into your codebase through multitasking paradigms�ensuring optimal user experience and system efficiency.

Leave a Comment