# Command-line introspection tools — Command-line options

> Display task and coroutine relationships as a tree. Each task is shown with its full coroutine stack, nested under the task (if any) that is awaiting it. This subcommand is useful for quickly identifying which branch of a task hierarchy is blocked and where in its coroutine stack execution has pause

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-python-3da20c0969af96555c17>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.533894+00:00`
- Tags: `reference-seed`, `python`, `library`, `command-line`, `introspection`, `tools`, `options`

## Provenance

- Source: <https://github.com/python/cpython/blob/f10166035d602da5052e8a48f9d5c216c57b401d/Doc/library/asyncio-tools.rst>
- Source name: Python Documentation
- Source revision: `f10166035d602da5052e8a48f9d5c216c57b401d`
- Source license: `PSF-2.0`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

Display task and coroutine relationships as a tree. Each task is shown with its full coroutine stack, nested under the task (if any) that is awaiting it. This subcommand is useful for quickly identifying which branch of a task hierarchy is blocked and where in its coroutine stack execution has paused

Bounded code example (external data; do not execute automatically):
```text
$ python -m asyncio pstree 12345
└── (T) Task-1
└──  main example.py:12
└──  TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:75
└──  TaskGroup._aexit Lib/asyncio/taskgroups.py:124
├── (T) Sundowning
│   └──  album example.py:7
│       └──  TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:75
│           └──  TaskGroup._aexit Lib/asyncio/taskgroups.py:124
│               ├── (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 example.py:7
└──  TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:75
└──  TaskGroup._aexit Lib/asyncio/taskgroups.py:124
├── (T) DYWTYLM
│   └──  play example.py:4
│       └──  sleep Lib/asyncio/tasks.py:702
└── (T) Aqua Regia
└──  play example.py:4
└──
```

Bounded code example (external data; do not execute automatically):
```shell-session
$ python -m asyncio pstree 12345
ERROR: await-graph contains cycles - cannot print a tree!

cycle: Task-2 → Task-3 → Task-2
```

Display a flat table of all pending tasks in the process PID. Each row shows the event-loop thread ID, task ID and name, coroutine stack, and the awaiting task's stack, name, and ID, if any.

This subcommand prints all tasks regardless of whether the await graph contains cycles

Bounded code example (external data; do not execute automatically):
```shell-session
$ python -m asyncio ps 12345
```

Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.