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gh-135371: Fix asyncio introspection output to include internal coroutine chains #135436

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59 changes: 37 additions & 22 deletions Doc/whatsnew/3.14.rst
Original file line number Diff line number Diff line change
Expand Up @@ -816,43 +816,58 @@ Executing the new tool on the running process will yield a table like this:
python -m asyncio ps 12345
tid task id task name coroutine chain awaiter name awaiter id
---------------------------------------------------------------------------------------------------------------------------------------
8138752 0x564bd3d0210 Task-1 0x0
8138752 0x564bd3d0410 Sundowning _aexit -> __aexit__ -> main Task-1 0x564bd3d0210
8138752 0x564bd3d0610 TMBTE _aexit -> __aexit__ -> main Task-1 0x564bd3d0210
8138752 0x564bd3d0810 TNDNBTG _aexit -> __aexit__ -> album Sundowning 0x564bd3d0410
8138752 0x564bd3d0a10 Levitate _aexit -> __aexit__ -> album Sundowning 0x564bd3d0410
8138752 0x564bd3e0550 DYWTYLM _aexit -> __aexit__ -> album TMBTE 0x564bd3d0610
8138752 0x564bd3e0710 Aqua Regia _aexit -> __aexit__ -> album TMBTE 0x564bd3d0610
or:
tid task id task name coroutine stack awaiter chain awaiter name awaiter id
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
1935500 0x7fc930c18050 Task-1 TaskGroup._aexit -> TaskGroup.__aexit__ -> main 0x0
1935500 0x7fc930c18230 Sundowning TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050
1935500 0x7fc93173fa50 TMBTE TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050
1935500 0x7fc93173fdf0 TNDNBTG sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230
1935500 0x7fc930d32510 Levitate sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230
1935500 0x7fc930d32890 DYWTYLM sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50
1935500 0x7fc93161ec30 Aqua Regia sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50
or a tree like this:

.. code-block:: bash
python -m asyncio pstree 12345
└── (T) Task-1
└── main
└── __aexit__
└── _aexit
└── main example.py:13
└── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72
└── TaskGroup._aexit Lib/asyncio/taskgroups.py:121
├── (T) Sundowning
│ └── album
│ └── __aexit__
│ └── _aexit
│ └── album example.py:8
│ └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72
│ └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121
│ ├── (T) TNDNBTG
│ │ └── play example.py:4
│ │ └── sleep Lib/asyncio/tasks.py:702
│ └── (T) Levitate
│ └── play example.py:4
│ └── sleep Lib/asyncio/tasks.py:702
└── (T) TMBTE
└── album
└── __aexit__
└── _aexit
└── album example.py:8
└── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72
└── TaskGroup._aexit Lib/asyncio/taskgroups.py:121
├── (T) DYWTYLM
│ └── play example.py:4
│ └── sleep Lib/asyncio/tasks.py:702
└── (T) Aqua Regia
└── play example.py:4
└── sleep Lib/asyncio/tasks.py:702
If a cycle is detected in the async await graph (which could indicate a
programming issue), the tool raises an error and lists the cycle paths that
prevent tree construction.
prevent tree construction:

.. code-block:: bash
python -m asyncio pstree 12345
ERROR: await-graph contains cycles - cannot print a tree!
cycle: Task-2 → Task-3 → Task-2
(Contributed by Pablo Galindo, Łukasz Langa, Yury Selivanov, and Marta
Gomez Macias in :gh:`91048`.)
Expand Down
162 changes: 95 additions & 67 deletions Lib/asyncio/tools.py
Original file line number Diff line number Diff line change
@@ -1,11 +1,10 @@
"""Tools to analyze tasks running in asyncio programs."""

from collections import defaultdict
from collections import defaultdict, namedtuple
from itertools import count
from enum import Enum
import sys
from _remote_debugging import RemoteUnwinder

from _remote_debugging import RemoteUnwinder, FrameInfo

class NodeType(Enum):
COROUTINE = 1
Expand All @@ -26,51 +25,75 @@ def __init__(


# ─── indexing helpers ───────────────────────────────────────────
def _format_stack_entry(elem: tuple[str, str, int] | str) -> str:
if isinstance(elem, tuple):
fqname, path, line_no = elem
return f"{fqname} {path}:{line_no}"

def _format_stack_entry(elem: str|FrameInfo) -> str:
if not isinstance(elem, str):
if elem.lineno == 0 and elem.filename == "":
return f"{elem.funcname}"
else:
return f"{elem.funcname} {elem.filename}:{elem.lineno}"
return elem


def _index(result):
id2name, awaits = {}, []
for _thr_id, tasks in result:
for tid, tname, awaited in tasks:
id2name[tid] = tname
for stack, parent_id in awaited:
stack = [_format_stack_entry(elem) for elem in stack]
awaits.append((parent_id, stack, tid))
return id2name, awaits


def _build_tree(id2name, awaits):
id2name, awaits, task_stacks = {}, [], {}
for awaited_info in result:
for task_info in awaited_info.awaited_by:
task_id = task_info.task_id
task_name = task_info.task_name
id2name[task_id] = task_name

# Store the internal coroutine stack for this task
if task_info.coroutine_stack:
for coro_info in task_info.coroutine_stack:
call_stack = coro_info.call_stack
internal_stack = [_format_stack_entry(frame) for frame in call_stack]
task_stacks[task_id] = internal_stack

# Add the awaited_by relationships (external dependencies)
if task_info.awaited_by:
for coro_info in task_info.awaited_by:
call_stack = coro_info.call_stack
parent_task_id = coro_info.task_name
stack = [_format_stack_entry(frame) for frame in call_stack]
awaits.append((parent_task_id, stack, task_id))
return id2name, awaits, task_stacks


def _build_tree(id2name, awaits, task_stacks):
id2label = {(NodeType.TASK, tid): name for tid, name in id2name.items()}
children = defaultdict(list)
cor_names = defaultdict(dict) # (parent) -> {frame: node}
cor_id_seq = count(1)

def _cor_node(parent_key, frame_name):
"""Return an existing or new (NodeType.COROUTINE, …) node under *parent_key*."""
bucket = cor_names[parent_key]
if frame_name in bucket:
return bucket[frame_name]
node_key = (NodeType.COROUTINE, f"c{next(cor_id_seq)}")
id2label[node_key] = frame_name
children[parent_key].append(node_key)
bucket[frame_name] = node_key
cor_nodes = defaultdict(dict) # Maps parent -> {frame_name: node_key}
next_cor_id = count(1)

def get_or_create_cor_node(parent, frame):
"""Get existing coroutine node or create new one under parent"""
if frame in cor_nodes[parent]:
return cor_nodes[parent][frame]

node_key = (NodeType.COROUTINE, f"c{next(next_cor_id)}")
id2label[node_key] = frame
children[parent].append(node_key)
cor_nodes[parent][frame] = node_key
return node_key

# lay down parent ➜ …frames… ➜ child paths
# Build task dependency tree with coroutine frames
for parent_id, stack, child_id in awaits:
cur = (NodeType.TASK, parent_id)
for frame in reversed(stack): # outer-most → inner-most
cur = _cor_node(cur, frame)
for frame in reversed(stack):
cur = get_or_create_cor_node(cur, frame)

child_key = (NodeType.TASK, child_id)
if child_key not in children[cur]:
children[cur].append(child_key)

# Add coroutine stacks for leaf tasks
awaiting_tasks = {parent_id for parent_id, _, _ in awaits}
for task_id in id2name:
if task_id not in awaiting_tasks and task_id in task_stacks:
cur = (NodeType.TASK, task_id)
for frame in reversed(task_stacks[task_id]):
cur = get_or_create_cor_node(cur, frame)

return id2label, children


Expand Down Expand Up @@ -129,12 +152,12 @@ def build_async_tree(result, task_emoji="(T)", cor_emoji=""):
The call tree is produced by `get_all_async_stacks()`, prefixing tasks
with `task_emoji` and coroutine frames with `cor_emoji`.
"""
id2name, awaits = _index(result)
id2name, awaits, task_stacks = _index(result)
g = _task_graph(awaits)
cycles = _find_cycles(g)
if cycles:
raise CycleFoundException(cycles, id2name)
labels, children = _build_tree(id2name, awaits)
labels, children = _build_tree(id2name, awaits, task_stacks)

def pretty(node):
flag = task_emoji if node[0] == NodeType.TASK else cor_emoji
Expand All @@ -154,35 +177,40 @@ def render(node, prefix="", last=True, buf=None):


def build_task_table(result):
id2name, awaits = _index(result)
id2name, _, _ = _index(result)
table = []
for tid, tasks in result:
for task_id, task_name, awaited in tasks:
if not awaited:
table.append(
[
tid,
hex(task_id),
task_name,
"",
"",
"0x0"
]
)
for stack, awaiter_id in awaited:
stack = [elem[0] if isinstance(elem, tuple) else elem for elem in stack]
coroutine_chain = " -> ".join(stack)
awaiter_name = id2name.get(awaiter_id, "Unknown")
table.append(
[
tid,
hex(task_id),
task_name,
coroutine_chain,
awaiter_name,
hex(awaiter_id),
]
)

for awaited_info in result:
thread_id = awaited_info.thread_id
for task_info in awaited_info.awaited_by:
# Get task info
task_id = task_info.task_id
task_name = task_info.task_name

# Build coroutine stack string
frames = [frame for coro in task_info.coroutine_stack
for frame in coro.call_stack]
coro_stack = " -> ".join(_format_stack_entry(x).split(" ")[0]
for x in frames)

# Handle tasks with no awaiters
if not task_info.awaited_by:
table.append([thread_id, hex(task_id), task_name, coro_stack,
"", "", "0x0"])
continue

# Handle tasks with awaiters
for coro_info in task_info.awaited_by:
parent_id = coro_info.task_name
awaiter_frames = [_format_stack_entry(x).split(" ")[0]
for x in coro_info.call_stack]
awaiter_chain = " -> ".join(awaiter_frames)
awaiter_name = id2name.get(parent_id, "Unknown")
parent_id_str = (hex(parent_id) if isinstance(parent_id, int)
else str(parent_id))

table.append([thread_id, hex(task_id), task_name, coro_stack,
awaiter_chain, awaiter_name, parent_id_str])

return table

Expand Down Expand Up @@ -211,11 +239,11 @@ def display_awaited_by_tasks_table(pid: int) -> None:
table = build_task_table(tasks)
# Print the table in a simple tabular format
print(
f"{'tid':<10} {'task id':<20} {'task name':<20} {'coroutine chain':<50} {'awaiter name':<20} {'awaiter id':<15}"
f"{'tid':<10} {'task id':<20} {'task name':<20} {'coroutine stack':<50} {'awaiter chain':<50} {'awaiter name':<15} {'awaiter id':<15}"
)
print("-" * 135)
print("-" * 180)
for row in table:
print(f"{row[0]:<10} {row[1]:<20} {row[2]:<20} {row[3]:<50} {row[4]:<20} {row[5]:<15}")
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:
Expand Down
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