GeezerVison is showing github.com — `python -m asyncio ps` fails if any task name is longer than 255 characters · Issue #157788 · python/cpython
python -m asyncio ps fails if any task name is longer than 255 characters #157788
DescriptionBug report
Bug description:
One task name longer than 255 characters makes python -m asyncio ps fail for the whole process. The length limit is treated as a validity check instead of a cap.
Repro:
import asyncio
import os
from _remote_debugging import RemoteUnwinder
async def main():
asyncio.create_task(asyncio.sleep(10), name='x' * 256)
await asyncio.sleep(0)
print(RemoteUnwinder(os.getpid()).get_all_awaited_by())
asyncio.run(main())
Actually:
Traceback (most recent call last):
File "/Users/timofeiivankov/cpython/repro.py", line 10, in <module>
asyncio.run(main())
~~~~~~~~~~~^^^^^^^^
File "/Users/timofeiivankov/cpython/Lib/asyncio/runners.py", line 205, in run
return runner.run(main)
~~~~~~~~~~^^^^^^
File "/Users/timofeiivankov/cpython/Lib/asyncio/runners.py", line 128, in run
return self._loop.run_until_complete(task)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/Users/timofeiivankov/cpython/Lib/asyncio/base_events.py", line 725, in run_until_complete
return future.result()
~~~~~~~~~~~~~^^
File "/Users/timofeiivankov/cpython/repro.py", line 8, in main
print(RemoteUnwinder(os.getpid()).get_all_awaited_by())
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
RuntimeError: Invalid string length (256) at 0x101493800
Expected: the call returns and the long name comes back truncated:
[AwaitedInfo(thread_id=21170325, awaited_by=[
TaskInfo(task_id=4312485712, task_name='Task-1', ...),
TaskInfo(task_id=4312485232, task_name='xxx…' (truncated to 255), ...)])]
Proposed fix: Truncate to the limit instead of raising in object_reading.c
I have a fix ready for that
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Linked PRs
Activityencukou commented on Sep 21, 2026 deadlovelll commented on Sep 21, 2026 ContributorAuthor More actions added 3 commits that reference this issue on Sep 22, 2026gh-157788: Fix `test_long_task_name_is_truncated` by not hardcoding m…
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