Why does Python RuntimeWarning: Coroutine Was Never Awaited Occur?
Below, are the reasons of occurring “Runtimewarning: Coroutine Was Never Awaited” in Python:
- Missing Await Keyword
- Incorrect Usage of Coroutine
- Nested Coroutines
Missing Wait Keyword
The most straightforward cause of this warning is forgetting to use the await keyword before calling a coroutine function and this lead to this warning.
Python3
async def example_coroutine(): print("This is a coroutine")#Missing await keywordexample_coroutine() |
Output:
Solution.py:5: RuntimeWarning: coroutine 'example_coroutine' was never awaited
example_coroutine()
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Incorrect Usage of Coroutine
Another reason for the warning may be using a coroutine in a synchronous context where the asynchronous features are not supported.
Python3
async def example_coroutine(): print("This is a coroutine")result = example_coroutine() |
Output:
sys:1: RuntimeWarning: coroutine 'example_coroutine' was never awaited
Nested Coroutines
If you have nested coroutine calls make sure that each coroutine is properly awaited at its respective level otherwise it will raise the error.
Python3
async def outer_coroutine(): await inner_coroutine() async def inner_coroutine(): print("Nested coroutine")outer_coroutine() |
Output:
Solution.py:7: RuntimeWarning: coroutine 'outer_coroutine' was never awaited
outer_coroutine()
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Python RuntimeWarning: Coroutine Was Never Awaited
Python’s asyncio module provides a powerful framework for writing asynchronous code using coroutines. While asyncio simplifies the handling of concurrent operations, developers may encounter the “RuntimeWarning: Coroutine Was Never Awaited” message, which indicates an issue with how coroutines are being used.
What is “Runtimewarning: Coroutine Was Never Awaited”?
The warning “RuntimeWarning: Coroutine Was Never Awaited” typically arises when a coroutine function is defined but not awaited properly. In Python, a coroutine is a special type of function that can be paused and resumed, allowing for asynchronous execution. When you define a coroutine, you must use the await keyword to execute it. Failure to do so can result in a runtime warning.
Syntax:
Runtimewarning: Coroutine Was Never Awaited