Enable tracemalloc to get the object allocation traceback

# Enable tracemalloc to get the object allocation traceback

The Python "RuntimeWarning: Enable tracemalloc to get the object allocation traceback" occurs when you forget to await a coroutine.

To resolve the issue, make sure to await all coroutines in your Python script.

Here is an example of when the warning is shown.

main.py

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import asyncio


async def my_coroutine():
    print('bobby')

    # ⛔️ RuntimeWarning: coroutine 'sleep' was never awaited
    #   asyncio.sleep(0.5)
    # RuntimeWarning: Enable tracemalloc to get the object allocation traceback

    asyncio.sleep(0.5) # 👈️ forgot to await asyncio.sleep()

    print('hadz.com')


loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)


async def main():
    tasks = []
    asyncio.create_task(my_coroutine())

    tasks.append(asyncio.create_task(my_coroutine()))

    await asyncio.wait(tasks)

loop.run_until_complete(main())
loop.close()

runtime warning enable tracemalloc to get the object allocation traceback

The issue occurred because I forgot to await the coroutine that is returned from asyncio.sleep().

# Make sure to `await` all coroutines to resolve the issue

I just have to add the await keyword to await the coroutine to resolve the issue.

In other words, this:

main.py

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# ⛔️ Incorrect
asyncio.sleep(0.5)

Becomes this:

main.py

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# ✅ Correct
await asyncio.sleep(0.5)

Here is the complete example.

main.py

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import asyncio


async def my_coroutine():
    print('bobby')

    asyncio.sleep(0.5)

    print('hadz.com')


loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)


async def main():
    tasks = []
    asyncio.create_task(my_coroutine())

    tasks.append(asyncio.create_task(my_coroutine()))

    await asyncio.wait(tasks)

loop.run_until_complete(main())
loop.close()

await all coroutines

You have to await all coroutines in your code.

For example, coroutines are returned from calls to asyncio.sleep() and asyncio.wait().

You can hover over a method in your IDE to see if it returns a coroutine.

Here is an example that does that in VS Code.

check if method returns coroutine

# You also need to await `async` functions

Note that async functions are also awaitable.

For example, the following code sample shows the warning.

main.py

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import asyncio


async def greet(name):
    return f'hello {name}'


async def main():
    # ⛔️ RuntimeWarning: Enable tracemalloc to get the object allocation traceback
    greet('bobby hadz') # 👈️ Forgot to await greet()

asyncio.run(main())

forgetting to await async functions

The warning is shown because I forgot to await the greet async function.

Here is the corrected version of the code.

main.py

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import asyncio


async def greet(name):
    return f'hello {name}'


async def main():
    print(await greet('bobby hadz'))

asyncio.run(main())

make sure to await async functions

Python coroutines are awaitable, so they can be awaited from other coroutines.

A coroutine is considered to be:

a coroutine function: an async def function.
a coroutine object: an object that is returned by calling a coroutine function.

If you need to call an async function outside an event loop, use the asyncio.run() method.

main.py

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import asyncio


async def greet(name):
    return f'hello {name}'


print(asyncio.run(greet('bobby hadz')))

using asyncio run method

# Additional Resources

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Enable tracemalloc to get the object allocation traceback