How to use coroutine functions in Tornado

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by vigneshchennai74 dot icon Updated: Nov 9, 2023

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A coroutine is a special type of function in Python. Coroutine helps in cooperative multitasking or concurrency. Unlike regular functions, we can pause coroutines at specific points in their execution. 

They help in asynchronous programming to handle non-blocking I/O operations. Coroutines are versatile tools in Python for managing concurrent tasks.  

Types of Coroutines:  

  • Synchronous Coroutines: These are regular Python functions with the `async` keyword added. While they are less common, we can use them with the `await` keyword to pause their execution.   
  • Asynchronous Coroutine: Python's `asyncio` library provides a more comprehensive framework for asynchronous programming. Asynchronous coroutines help for this purpose. We can schedule it to run, making them ideal for I/O-bound operations. It helps in network communication and managing concurrency in large applications.  

Use Cases for Coroutines: 

  • Coroutines play a crucial role in large applications, such as web servers. They can handle many client requests. It ensures that the server remains responsive even under heavy loads.  
  • Isolated Short Tasks: Coroutines are valuable for handling short, non-blocking tasks. These tasks may include making HTTP requests and reading/writing files. Also, it helps in responding to concurrent user interactions in graphical user interfaces.  

Advantages of Using Coroutines: 

  • Improved Responsiveness: Coroutines allow applications to remain responsive even during I/O-bound operations. We should pause and yield control if waiting for Input or Output. We should use coroutines to prevent the main thread from blocking. It ensures a smoother user experience.  
  • Decreased Development Time: Coroutines simplify complex concurrency scenarios. They make code more readable and maintainable. We can use the `async` and `await` keywords to express asynchronous logic. That will reduce the complexity of callbacks and threads.  


  • Emphasize the benefits of coroutines. They play a crucial role in improving application responsiveness. It makes concurrent programming more manageable.  
  • Creating Coroutines: Explain how to define coroutines using the async keyword. Then, discuss their usage, incorporating the await keyword. Provide examples to illustrate their usage. 
  • Best Practices: Cover best practices for coroutines use of appropriate libraries. It helps in structuring code for clarity and maintainability.  


Coroutines are a unique feature of Python's programming landscape. Their ability to handle concurrency tasks has made them popular among developers. They are essential for building responsive applications. It is true, especially in scenarios where I/O-bound operations are prevalent. They testify to their adaptability to keep up with modern programming demands.   

Preview of the output that you will get on running this code from your IDE


In this solution we have used Tornado library

  1. Download and install VS Code on your desktop.
  2. Open VS Code and create a new file in the editor.
  3. Copy the code snippet that you want to run, using the "Copy" button or by selecting the text and using the copy command (Ctrl+C on Windows/Linux or Cmd+C on Mac).,
  4. Paste the code into your file in VS Code, and save the file with a meaningful name and the appropriate file extension for Python use (.py).file extension.
  5. To run the code, open the file in VS Code and click the "Run" button in the top menu, or use the keyboard shortcut Ctrl+Alt+N (on Windows and Linux) or Cmd+Alt+N (on Mac). The output of your code will appear in the VS Code output console.
  6. Paste the code into your file in VS Code.
  7. Save the file with a meaningful name and the appropriate file extension for Python use (.py).
  8. Add this line in the start of the code import tornado.ioloopat.
  9. Remove the last line of the code.
  10. Add these lines at the end of the code
  • if __name__ == "__main__":
  •   unittest.main()
  •   tornado.ioloop.IOLoop.current().start()

11.Save and Run the Code

I hope this is useful to you. I have added the version information in the following section. I found this code snippet by searching " Howto do unittest for tornado + async def? " in Kandi. you can try any use case.

Environment Tested

I tested this solution in the following versions. Please be aware of any changes when working with other versions.

  1. The solution is created and tested using Vscode 1.77.2 version
  2. The solution is created in Tornado 6.3.3 version
  3. The solution is created in Python 3.7.15 version

This code explains How to use coroutine functions in Tornado . This process also facilitates an easy-to-use, hassle-free method to create a hands-on working version of code which would helpHow to use coroutine functions in Tornado in Python.

Dependent Library

tornadoby tornadoweb

Python doticonstar image 21143 doticonVersion:v6.3.0b1doticon
License: Permissive (Apache-2.0)

Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.


            tornadoby tornadoweb

            Python doticon star image 21143 doticonVersion:v6.3.0b1doticon License: Permissive (Apache-2.0)

            Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed.

                      If you do not have the tornado that is required to run this code, you can install it by clicking on the above link and copying the pip Install command from the Flask page in Kandi.

                      You can search for any dependent library on Kandi like tornado


                      1. What is the asyncio Task implementation, and how does it work with Python Coroutines?  

                      `asyncio.Task` is a way to execute a Python coroutine. It works by scheduling and managing the execution of coroutines. It allows them to run in parallel.  

                      2. How are asyncio APIs used for working with coroutines in Python?  

                      asyncio provides APIs to work through the `async/await` syntax and functions. You can use `await` to pause a coroutine and use functions like `` to manage the event loop.  

                      3. Are there any alternative implementations that support coroutines more than the standard version?  

                      No, Python's `asyncio` library is the standard and adopted way to work with coroutines. While other libraries exist, `asyncio` is the most used for managing asynchronous tasks.  

                      4. What does "async def display" do? What advantages does it offer over other methods of running coroutines? 

                      `async def display` defines an asynchronous coroutine. It offers the advantage of non-blocking execution, allowing other tasks to run. It can improve responsiveness in I/O-bound operations.  

                      5. What is a context manager, and how can it help when writing Python Coroutines?  

                      A context manager is an object. It enables the use of the `with` statement. It can help coroutines by managing resources and ensuring proper setup/teardown operations.  


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