Usage¶

Use aioeventlet with asyncio¶

aioeventlet can be used with asyncio, coroutines written with yield from .... To use aioeventlet with asyncio, set the event loop policy before using an event loop. Example:

import aioeventlet
import asyncio

asyncio.set_event_loop_policy(aioeventlet.EventLoopPolicy())
# ....

Setting the event loop policy should be enough to examples of the asyncio documentation with the aioeventlet event loop.

Hello World:

import aioeventlet
import asyncio

def hello_world():
    print("Hello World")
    loop.stop()

asyncio.set_event_loop_policy(aioeventlet.EventLoopPolicy())
loop = asyncio.get_event_loop()
loop.call_soon(hello_world)
loop.run_forever()
loop.close()

Use aioeventlet with trollius¶

Warning

The trollius project is now deprecated. It’s now recommended to use aioeventlet with asyncio.

aioeventlet can be used with trollius, coroutines written with yield From(...). Using aioeventlet with trollius is a good start to port project written for eventlet to trollius.

To use aioeventlet with trollius, set the event loop policy before using an event loop, example:

import aioeventlet
import trollius

trollius.set_event_loop_policy(aioeventlet.EventLoopPolicy())
# ....

Hello World:

import aioeventlet
import trollius as asyncio

def hello_world():
    print("Hello World")
    loop.stop()

asyncio.set_event_loop_policy(aioeventlet.EventLoopPolicy())
loop = asyncio.get_event_loop()
loop.call_soon(hello_world)
loop.run_forever()
loop.close()

Threads¶

Running an event loop in a thread different than the main thread is currently experimental.

An eventlet Event object is not thread-safe, it must only be used in the same thread. Use threading.Event to signal events between threads, and threading.Queue to pass data between threads.

Use threading = eventlet.patcher.original('threading') to get the original threading instead of import threading.

It is not possible to run two aioeventlet event loops in the same thread.

Debug mode¶

To enable the debug mode globally when using trollius, set the environment variable TROLLIUSDEBUG to 1. To see debug traces, set the log level of the trollius logger to logging.DEBUG. The simplest configuration is:

import logging
# ...
logging.basicConfig(level=logging.DEBUG)

If you use asyncio, use the PYTHONASYNCIODEBUG environment variable instead of the TROLLIUSDEBUG variable.

You can also call loop.set_debug(True) to enable the debug mode of the event loop, but it enables less debug checks.

API¶

aioeventlet specific functions:

Warning

aioeventlet API is not considered as stable yet.

yield_future¶

yield_future(future, loop=None)¶

Wait for a future, a task, or a coroutine object from a greenthread.

Return the result or raise the exception of the future.

The function must not be called from the greenthread running the aioeventlet event loop.

Changed in version 0.4: Rename the function from wrap_future() to yield_future().

Changed in version 0.3: Coroutine objects are also accepted. Added the loop parameter. An exception is raised if it is called from the greenthread of the aioeventlet event loop.

Example of greenthread waiting for a trollius task. The progress() callback is called regulary to see that the event loop in not blocked:

import aioeventlet
import eventlet
import trollius as asyncio
from trollius import From, Return

def progress():
    print("computation in progress...")
    loop.call_later(0.5, progress)

@asyncio.coroutine
def coro_slow_sum(x, y):
    yield From(asyncio.sleep(1.0))
    raise Return(x + y)

def green_sum():
    loop.call_soon(progress)

    value = aioeventlet.yield_future(coro_slow_sum(1, 2))
    print("1 + 2 = %s" % value)

    loop.stop()

asyncio.set_event_loop_policy(aioeventlet.EventLoopPolicy())
eventlet.spawn(green_sum)
loop = asyncio.get_event_loop()
loop.run_forever()
loop.close()

Output:

computation in progress...
computation in progress...
computation in progress...
1 + 2 = 3

wrap_greenthread¶

wrap_greenthread(gt)¶

Wrap an eventlet GreenThread, or a greenlet, into a Future object.

The Future object waits for the completion of a greenthread. The result or the exception of the greenthread will be stored in the Future object.

The greenthread must be wrapped before its execution starts. If the greenthread is running or already finished, an exception is raised.

For greenlets, the run attribute must be set.

Changed in version 0.3: An exception is now raised if the greenthread is running or already finished. In debug mode, the exception is not more logged to sys.stderr for greenthreads.

Example of trollius coroutine waiting for a greenthread. The progress() callback is called regulary to see that the event loop in not blocked:

import aioeventlet
import eventlet
import trollius as asyncio
from trollius import From, Return

def progress():
    print("computation in progress...")
    loop.call_later(0.5, progress)

def slow_sum(x, y):
    eventlet.sleep(1.0)
    return x + y

@asyncio.coroutine
def coro_sum():
    loop.call_soon(progress)

    gt = eventlet.spawn(slow_sum, 1, 2)
    fut = aioeventlet.wrap_greenthread(gt, loop=loop)

    result = yield From(fut)
    print("1 + 2 = %s" % result)

asyncio.set_event_loop_policy(aioeventlet.EventLoopPolicy())
loop = asyncio.get_event_loop()
loop.run_until_complete(coro_sum())
loop.close()

Output:

computation in progress...
computation in progress...
computation in progress...
1 + 2 = 3

Installation¶

Install aioeventlet with pip¶

Type:

pip install aioeventlet

Install aioeventlet on Windows with pip¶

Procedure for Python 2.7:

If pip is not installed yet, install pip: download get-pip.py and type:
```
\Python27\python.exe get-pip.py
```

Install aioeventlet with pip:

\Python27\python.exe -m pip install aioeventlet

pip also installs dependencies: eventlet and trollius

Manual installation of aioeventlet¶

Requirements:

eventlet 0.14 or newer
asyncio or trollius:
- Python 3.4 and newer: asyncio is now part of the stdlib (only eventlet is needed)
- Python 3.3: need Tulip 0.4.1 or newer (pip install asyncio), but Tulip 3.4.1 or newer is recommended
- Python 2.7: need Trollius 0.3 or newer (pip install trollius), but Trollius 1.0 or newer is recommended

Type:

python setup.py install

Run tests¶

Run tests with tox¶

The tox project can be used to build a virtual environment with all runtime and test dependencies and run tests against different Python versions (2.7, 3.3, 3.4, 3.5).

To test all Python versions, just type:

tox

To run tests with Python 2.7, type:

tox -e py27

To run tests against other Python versions:

py27: Python 2.7
py27_patch: Python 2.7 with eventlet monkey patching
py27_old: Python 2.7 with the oldest supported versions of eventlet and trollius
py33: Python 3.3
py3_patch: Python 3 with eventlet monkey patching
py3_old: Python 3 with the oldest supported versions of eventlet and tulip
py34: Python 3.4
py35: Python 3.5

Run tests manually¶

To run unit tests, the mock module is need on Python older than 3.3.

Run the following command:

python runtests.py -r