https://github.com/python/cpython/commit/4adffd9efad7052ad0a22743dd678d0201ec0286 commit: 4adffd9efad7052ad0a22743dd678d0201ec0286 branch: main author: Bartosz Sławecki <[email protected]> committer: pablogsal <[email protected]> date: 2026-04-13T22:10:54Z summary:
gh-144881: Add retry logic to asyncio debugging tools (#148530) Transient errors can occur when attaching to a process that is actively using thread delegation (e.g. asyncio.to_thread). Add a retry loop to _get_awaited_by_tasks for RuntimeError, OSError, UnicodeDecodeError, and MemoryError, and expose --retries CLI flag on both `ps` and `pstree` subcommands (default: 3). Co-authored-by: Pablo Galindo Salgado <[email protected]> Co-authored-by: Stan Ulbrych <[email protected]> files: A Misc/NEWS.d/next/Library/2026-04-13-21-38-50.gh-issue-144881.3kPqXw.rst M Lib/asyncio/__main__.py M Lib/asyncio/tools.py diff --git a/Lib/asyncio/__main__.py b/Lib/asyncio/__main__.py index 0bf3bdded40200..8ee09b38469d4c 100644 --- a/Lib/asyncio/__main__.py +++ b/Lib/asyncio/__main__.py @@ -162,17 +162,29 @@ def interrupt(self) -> None: "ps", help="Display a table of all pending tasks in a process" ) ps.add_argument("pid", type=int, help="Process ID to inspect") + ps.add_argument( + "--retries", + type=int, + default=3, + help="Number of retries on transient attach errors", + ) pstree = subparsers.add_parser( "pstree", help="Display a tree of all pending tasks in a process" ) pstree.add_argument("pid", type=int, help="Process ID to inspect") + pstree.add_argument( + "--retries", + type=int, + default=3, + help="Number of retries on transient attach errors", + ) args = parser.parse_args() match args.command: case "ps": - asyncio.tools.display_awaited_by_tasks_table(args.pid) + asyncio.tools.display_awaited_by_tasks_table(args.pid, retries=args.retries) sys.exit(0) case "pstree": - asyncio.tools.display_awaited_by_tasks_tree(args.pid) + asyncio.tools.display_awaited_by_tasks_tree(args.pid, retries=args.retries) sys.exit(0) case None: pass # continue to the interactive shell diff --git a/Lib/asyncio/tools.py b/Lib/asyncio/tools.py index 62d6a71557fa37..2ac1738d15c6c7 100644 --- a/Lib/asyncio/tools.py +++ b/Lib/asyncio/tools.py @@ -231,27 +231,38 @@ def exit_with_permission_help_text(): print( "Error: The specified process cannot be attached to due to insufficient permissions.\n" "See the Python documentation for details on required privileges and troubleshooting:\n" - "https://docs.python.org/3.14/howto/remote_debugging.html#permission-requirements\n"; + "https://docs.python.org/3/howto/remote_debugging.html#permission-requirements\n";, + file=sys.stderr, ) sys.exit(1) -def _get_awaited_by_tasks(pid: int) -> list: - try: - return get_all_awaited_by(pid) - except RuntimeError as e: - while e.__context__ is not None: - e = e.__context__ - print(f"Error retrieving tasks: {e}") - sys.exit(1) - except PermissionError: - exit_with_permission_help_text() +_TRANSIENT_ERRORS = (RuntimeError, OSError, UnicodeDecodeError, MemoryError) + + +def _get_awaited_by_tasks(pid: int, retries: int = 3) -> list: + for attempt in range(retries + 1): + try: + return get_all_awaited_by(pid) + except PermissionError: + exit_with_permission_help_text() + except ProcessLookupError: + print(f"Error: process {pid} not found.", file=sys.stderr) + sys.exit(1) + except _TRANSIENT_ERRORS as e: + if attempt < retries: + continue + if isinstance(e, RuntimeError): + while e.__context__ is not None: + e = e.__context__ + print(f"Error retrieving tasks: {e}", file=sys.stderr) + sys.exit(1) -def display_awaited_by_tasks_table(pid: int) -> None: +def display_awaited_by_tasks_table(pid: int, retries: int = 3) -> None: """Build and print a table of all pending tasks under `pid`.""" - tasks = _get_awaited_by_tasks(pid) + tasks = _get_awaited_by_tasks(pid, retries=retries) table = build_task_table(tasks) # Print the table in a simple tabular format print( @@ -262,10 +273,10 @@ def display_awaited_by_tasks_table(pid: int) -> None: print(f"{row[0]:<10} {row[1]:<20} {row[2]:<20} {row[3]:<50} {row[4]:<50} {row[5]:<15} {row[6]:<15}") -def display_awaited_by_tasks_tree(pid: int) -> None: +def display_awaited_by_tasks_tree(pid: int, retries: int = 3) -> None: """Build and print a tree of all pending tasks under `pid`.""" - tasks = _get_awaited_by_tasks(pid) + tasks = _get_awaited_by_tasks(pid, retries=retries) try: result = build_async_tree(tasks) except CycleFoundException as e: diff --git a/Misc/NEWS.d/next/Library/2026-04-13-21-38-50.gh-issue-144881.3kPqXw.rst b/Misc/NEWS.d/next/Library/2026-04-13-21-38-50.gh-issue-144881.3kPqXw.rst new file mode 100644 index 00000000000000..0812dc9efb6d8b --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-04-13-21-38-50.gh-issue-144881.3kPqXw.rst @@ -0,0 +1,4 @@ +:mod:`asyncio` debugging tools (``python -m asyncio ps`` and ``pstree``) +now retry automatically on transient errors that can occur when attaching +to a process under active thread delegation. The number of retries can be +controlled with the ``--retries`` flag. Patch by Bartosz Sławecki. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
