https://github.com/defnull/pycopine

Latency and fault tolerance library inspired by Hystrix.
https://github.com/defnull/pycopine

Last synced: about 1 year ago
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Latency and fault tolerance library inspired by Hystrix.

• Host: GitHub
• URL: https://github.com/defnull/pycopine
• Owner: defnull
• Created: 2013-05-08T22:43:12.000Z (about 13 years ago)
• Default Branch: master
• Last Pushed: 2013-09-10T23:19:24.000Z (almost 13 years ago)
• Last Synced: 2025-04-11T19:53:09.965Z (about 1 year ago)
• Language: Python
• Homepage: https://pycopine.readthedocs.org
• Size: 242 KB
• Stars: 21
• Watchers: 1
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst

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README

          
Pycopine - Handle with Care

===========================

Pycopine is a latency and fault tolerance library designed to isolate points of

access to remote systems, services and 3rd party libraries, stop cascading

failure and enable resilience in complex distributed systems where failure

is inevitable.

As this copy-pasted text suggests, pycopine is heavily inspired by

`Hystrix `_. 

Prerequisites

-------------

Pycopine requires Python 3.2+, but may be backportet to 2.7 in the future.

(Planned) Features

------------------

* Detect and report failing services.

* Short-circuit services that fail on high load to help them recover.

* Monitor failure rates and performance metrics to detect bottlenecks.

* Manage thread pool and queue sizes on demand, at runtime, from everywhere.

* ... (more to come)

Example

-------

Lets say we want to speak to a remote service that is slow, unreliable or both:

.. code-block:: python

    import time

    import random

    

    def crappy_service(value):

        ''' The most useless piece of code ever.'''

        time.sleep(5)

        if 'OK' != random.choice(['OK', 'OK', 'SERVER ON FIRE']):

            raise RuntimeError('We broke something :(')

        return value

You could throw lots of threads and try/except clauses at the problem and hope

to not break the internet. Or you could use pycopine:

.. code-block:: python

    from pycopine import Command

    

    class MyCommand(Command):

        ''' Does nothing with the input, but with style. '''

    

        def run(self, value):

            return crappy_service(value)

        def fallback(self, value):

            return 'some fallback value'

    # Run and wait for the result

    result = MyCommand('input').result()

    # Give up after 2 seconds

    result = MyCommand('input').result(timeout=2)

    # Fire and forget

    MyCommand('input').submit()

    # Do stuff in parallel

    foo = MyCommand('input').submit()

    bar = MyCommand('input').submit()

    results = [foo.result(), bar.result()]

    # Change your mind midway through

    foobar = MyCommand('input').submit()

    if foobar.wait(timeout=2):

        result = foobar.result()

    else:

        foobar.cancel(RuntimeError('We have no time for this!'))