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Readme rework draft #163

Merged
merged 11 commits into from
Feb 25, 2021
221 changes: 199 additions & 22 deletions docs/README.rst
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tractor
=======
A `structured concurrent`_, async-native "`actor model`_" built on trio_ and multiprocessing_.
|logo| ``tractor``: next-gen Python parallelism

|gh_actions|
|docs|

.. _actor model: https://en.wikipedia.org/wiki/Actor_model
.. _trio: https://github.com/python-trio/trio
.. _multiprocessing: https://en.wikipedia.org/wiki/Multiprocessing
.. _multi-processing: https://en.wikipedia.org/wiki/Multiprocessing
.. _trionic: https://trio.readthedocs.io/en/latest/design.html#high-level-design-principles
.. _async sandwich: https://trio.readthedocs.io/en/latest/tutorial.html#async-sandwich
.. _structured concurrent: https://trio.discourse.group/t/concise-definition-of-structured-concurrency/228


``tractor`` is an attempt to bring trionic_ `structured concurrency`_ to
distributed multi-core Python; it aims to be the Python multi-processing
framework *you always wanted*.
``tractor`` is a `structured concurrent`_ "`actor model`_" built on trio_ and multi-processing_.

``tractor`` lets you spawn ``trio`` *"actors"*: processes which each run
a ``trio`` scheduled task tree (also known as an `async sandwich`_).
*Actors* communicate by exchanging asynchronous messages_ and avoid
sharing any state. This model allows for highly distributed software
architecture which works just as well on multiple cores as it does over
many hosts.
We pair structured concurrency and true multi-core parallelism with
the aim of being the multi-processing framework *you always wanted*.

The first step to grok ``tractor`` is to get the basics of ``trio`` down.
A great place to start is the `trio docs`_ and this `blog post`_.

.. _messages: https://en.wikipedia.org/wiki/Message_passing
.. _trio docs: https://trio.readthedocs.io/en/latest/
.. _blog post: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _structured concurrency: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _3 axioms: https://en.wikipedia.org/wiki/Actor_model#Fundamental_concepts
.. _unrequirements: https://en.wikipedia.org/wiki/Actor_model#Direct_communication_and_asynchrony
.. _async generators: https://www.python.org/dev/peps/pep-0525/

Features
--------
- **It's just** a ``trio`` API
- Infinitely nesteable process trees
- Built-in APIs for inter-process streaming
- A (first ever?) "native" multi-core debugger for Python using `pdb++`_
- Support for multiple process spawning backends
- A modular transport layer, allowing for custom serialization,
communications protocols, and environment specific IPC primitives


Zombie safe: self-destruct a process tree
-----------------------------------------
``tractor`` tries to protect you from zombies, no matter what.

.. code:: python

"""
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Per the reST specs,

Several constructs begin with a marker, and the body of the construct
must be indented relative to the marker.

where in this case, the code-block (I can't seem to find code even in Sphinx-flavored reST) body should be indented by 3 space. I believe that the editor picked this up and caused some indentation issues below.

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@goodboy goodboy Feb 24, 2021

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Oh so you mean after the .. there should be 3 spaces before the code::?

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Yep, e.g.

.. code-block:: python

   """
   ...
   async def target():
       try:
   ...

BTW could you please hide the resolved reviews, my international connection is terrible due to cable maintenance or something and GitHub's way of fetching content really does not help 😄

Run with a process monitor from a terminal using::

$TERM -e watch -n 0.1 "pstree -a $$" \
& python examples/parallelism/we_are_processes.py \
&& kill $!

"""
from multiprocessing import cpu_count
import os

import tractor
import trio


async def target():
print(
f"Yo, i'm '{tractor.current_actor().name}' "
f"running in pid {os.getpid()}"
)

await trio.sleep_forever()


async def main():

async with tractor.open_nursery() as n:

for i in range(cpu_count()):
await n.run_in_actor(target, name=f'worker_{i}')

print('This process tree will self-destruct in 1 sec...')
await trio.sleep(1)

# you could have done this yourself
raise Exception('Self Destructed')


if __name__ == '__main__':
try:
trio.run(main)
except Exception:
print('Zombies Contained')


If you can create zombie child processes (without using a system signal)
it **is a bug**.


"Native" multi-process debugging
--------------------------------
Using the magic of `pdb++`_ and our internal IPC, we've
been able to create a native feeling debugging experience for
any (sub-)process in your ``tractor`` tree.

.. code:: python

from os import getpid

import tractor
import trio


async def breakpoint_forever():
"Indefinitely re-enter debugger in child actor."
while True:
yield 'yo'
await tractor.breakpoint()


async def name_error():
"Raise a ``NameError``"
getattr(doggypants)


async def main():
"""Test breakpoint in a streaming actor.
"""
async with tractor.open_nursery(
debug_mode=True,
loglevel='error',
) as n:

p0 = await n.start_actor('bp_forever', enable_modules=[__name__])
p1 = await n.start_actor('name_error', enable_modules=[__name__])

# retreive results
stream = await p0.run(breakpoint_forever)
await p1.run(name_error)


if __name__ == '__main__':
trio.run(main)


You can run this with::

>>> python examples/debugging/multi_daemon_subactors.py

And, yes, there's a built-in crash handling mode B)

We're hoping to add a respawn-from-repl system soon!


Worker poolz are easy peasy
---------------------------
The initial ask from most new users is *"how do I make a worker
pool thing?"*.

``tractor`` is built to handle any SC (structured concurrent) process
tree you can imagine; a "worker pool" pattern is a trivial special
case.

We have a `full re-implementation <worker_pool>`_ of the std-lib's
``concurrent.futures.ProcessPoolExecutor`` example for reference.

You can run it like so (from this dir) to see the process tree in
real time::

$TERM -e watch -n 0.1 "pstree -a $$" \
& python examples/parallelism/concurrent_actors_primes.py \
&& kill $!

This uses no extra threads, fancy semaphores or futures; all we need
is ``tractor``'s IPC!


.. _worker_pool: https://github.com/goodboy/tractor/blob/master/examples/parallelism/concurrent_actors_primes.py

Install
-------
No PyPi release yet!

::
From git::

pip install git+git://github.com/goodboy/tractor.git


Under the hood
--------------
``tractor`` is an attempt to pair trionic_ `structured concurrency`_ with
distributed Python. You can think of it as a ``trio``
*-across-processes* or simply as an opinionated replacement for the
stdlib's ``multiprocessing`` but built on async programming primitives
from the ground up.

``tractor``'s nurseries let you spawn ``trio`` *"actors"*: new Python
processes which each run a ``trio`` scheduled runtime - a call to ``trio.run()``.

Don't be scared off by this description. ``tractor`` **is just** ``trio``
but with nurseries for process management and cancel-able streaming IPC.
If you understand how to work with ``trio``, ``tractor`` will give you
the parallelism you've been missing.

"Actors" communicate by exchanging asynchronous messages_ and avoid
sharing state. The intention of this model is to allow for highly
distributed software that, through the adherence to *structured
concurrency*, results in systems which fail in predictable and
recoverable ways.


What's on the TODO:
-------------------
Help us push toward the future.

- (Soon to land) ``asyncio`` support allowing for "infected" actors where
`trio` drives the `asyncio` scheduler via the astounding "`guest mode`_"
- Typed messaging protocols (ex. via ``msgspec``)
- Erlang-style supervisors via composed context managers


Feel like saying hi?
--------------------
This project is very much coupled to the ongoing development of
``trio`` (i.e. ``tractor`` gets most of its ideas from that brilliant
community). If you want to help, have suggestions or just want to
say hi, please feel free to reach us on in our `matrix channel`_. If
say hi, please feel free to reach us in our `matrix channel`_. If
matrix seems too hip, we're also mostly all in the the `trio gitter
channel`_!

.. _trio gitter channel: https://gitter.im/python-trio/general
.. _matrix channel: https://matrix.to/#/!tractor:matrix.org
.. _pdb++: https://github.com/pdbpp/pdbpp
.. _guest mode: https://trio.readthedocs.io/en/stable/reference-lowlevel.html?highlight=guest%20mode#using-guest-mode-to-run-trio-on-top-of-other-event-loops
.. _messages: https://en.wikipedia.org/wiki/Message_passing
.. _trio docs: https://trio.readthedocs.io/en/latest/
.. _blog post: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _structured concurrency: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _3 axioms: https://en.wikipedia.org/wiki/Actor_model#Fundamental_concepts
.. _unrequirements: https://en.wikipedia.org/wiki/Actor_model#Direct_communication_and_asynchrony
.. _async generators: https://www.python.org/dev/peps/pep-0525/


.. |gh_actions| image:: https://img.shields.io/endpoint.svg?url=https%3A%2F%2Factions-badge.atrox.dev%2Fgoodboy%2Ftractor%2Fbadge&style=popout-square
:target: https://actions-badge.atrox.dev/goodboy/tractor/goto

.. |docs| image:: https://readthedocs.org/projects/tractor/badge/?version=latest
:target: https://tractor.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status

.. |logo| image:: _static/tractor_logo_side.svg
:width: 250
:align: middle
109 changes: 109 additions & 0 deletions docs/github_readme/_sphinx_readme.rst
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tractor
=======
The Python async-native multi-core system *you always wanted*.


|gh_actions|
|docs|

.. _actor model: https://en.wikipedia.org/wiki/Actor_model
.. _trio: https://github.com/python-trio/trio
.. _multi-processing: https://en.wikipedia.org/wiki/Multiprocessing
.. _trionic: https://trio.readthedocs.io/en/latest/design.html#high-level-design-principles
.. _async sandwich: https://trio.readthedocs.io/en/latest/tutorial.html#async-sandwich
.. _structured concurrent: https://trio.discourse.group/t/concise-definition-of-structured-concurrency/228


``tractor`` is a `structured concurrent`_ "`actor model`_" built on trio_ and multi-processing_.

It is an attempt to pair trionic_ `structured concurrency`_ with
distributed Python. You can think of it as a ``trio``
*-across-processes* or simply as an opinionated replacement for the
stdlib's ``multiprocessing`` but built on async programming primitives
from the ground up.

Don't be scared off by this description. ``tractor`` **is just ``trio``**
but with nurseries for process management and cancel-able IPC.
If you understand how to work with ``trio``, ``tractor`` will give you
the parallelism you've been missing.

``tractor``'s nurseries let you spawn ``trio`` *"actors"*: new Python
processes which each run a ``trio`` scheduled task tree (also known as
an `async sandwich`_ - a call to ``trio.run()``). That is, each
"*Actor*" is a new process plus a ``trio`` runtime.

"Actors" communicate by exchanging asynchronous messages_ and avoid
sharing state. The intention of this model is to allow for highly
distributed software that, through the adherence to *structured
concurrency*, results in systems which fail in predictable and
recoverable ways.

The first step to grok ``tractor`` is to get the basics of ``trio`` down.
A great place to start is the `trio docs`_ and this `blog post`_.

.. _messages: https://en.wikipedia.org/wiki/Message_passing
.. _trio docs: https://trio.readthedocs.io/en/latest/
.. _blog post: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _structured concurrency: https://vorpus.org/blog/notes-on-structured-concurrency-or-go-statement-considered-harmful/
.. _3 axioms: https://en.wikipedia.org/wiki/Actor_model#Fundamental_concepts
.. _unrequirements: https://en.wikipedia.org/wiki/Actor_model#Direct_communication_and_asynchrony
.. _async generators: https://www.python.org/dev/peps/pep-0525/


Install
-------
No PyPi release yet!

::

pip install git+git://github.com/goodboy/tractor.git


Alluring Features
-----------------
- **It's just** ``trio``, but with SC applied to processes (aka "actors")
- Infinitely nesteable process trees
- Built-in API for inter-process streaming
- A (first ever?) "native" multi-core debugger for Python using `pdb++`_
- (Soon to land) ``asyncio`` support allowing for "infected" actors where
`trio` drives the `asyncio` scheduler via the astounding "`guest mode`_"


Example: self-destruct a process tree
-------------------------------------
.. literalinclude:: ../../examples/parallelism/we_are_processes.py
:language: python


The example you're probably after...
------------------------------------
It seems the initial query from most new users is "how do I make a worker
pool thing?".

``tractor`` is built to handle any SC process tree you can
imagine; the "worker pool" pattern is a trivial special case:

.. literalinclude:: ../../examples/parallelism/concurrent_actors_primes.py
:language: python


Feel like saying hi?
--------------------
This project is very much coupled to the ongoing development of
``trio`` (i.e. ``tractor`` gets most of its ideas from that brilliant
community). If you want to help, have suggestions or just want to
say hi, please feel free to reach us in our `matrix channel`_. If
matrix seems too hip, we're also mostly all in the the `trio gitter
channel`_!

.. _trio gitter channel: https://gitter.im/python-trio/general
.. _matrix channel: https://matrix.to/#/!tractor:matrix.org
.. _pdb++: https://github.com/pdbpp/pdbpp
.. _guest mode: https://trio.readthedocs.io/en/stable/reference-lowlevel.html?highlight=guest%20mode#using-guest-mode-to-run-trio-on-top-of-other-event-loops


.. |gh_actions| image:: https://img.shields.io/endpoint.svg?url=https%3A%2F%2Factions-badge.atrox.dev%2Fgoodboy%2Ftractor%2Fbadge&style=popout-square
:target: https://actions-badge.atrox.dev/goodboy/tractor/goto
.. |docs| image:: https://readthedocs.org/projects/tractor/badge/?version=latest
:target: https://tractor.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status
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