Reducer for similar simultaneously coroutines
Project description
About Async-Reduce
async_reduce(coroutine)
allows aggregate all similar simultaneous
ready to run coroutine
s and reduce to running only one coroutine
.
Other aggregated coroutine
s will get result from single coroutine
.
It can boost application performance in highly competitive execution of the similar asynchronous operations and reduce load for inner systems.
Quick example
from async_reduce import async_reduce
async def fetch_user_data(user_id: int) -> dict:
"""" Get user data from inner service """
url = 'http://inner-service/user/{}'.format(user_id)
return await http.get(url, timeout=10).json()
@web_server.router('/users/(\d+)')
async def handler_user_detail(request, user_id: int):
""" Handler for get detail information about user """
# all simultaneous requests of fetching user data for `user_id` will
# reduced to single request
user_data = await async_reduce(
fetch_user_data(user_id)
)
# sometimes ``async_reduce`` cannot detect similar coroutines and
# you should provide special argument `ident` for manually determination
user_statistics = await async_reduce(
DataBase.query('user_statistics').where(id=user_id).fetch_one(),
ident='db_user_statistics:{}'.format(user_id)
)
return Response(...)
In that example without using async_reduce
if client performs N
simultaneous requests like GET http://web_server/users/42
web_server
performs N requests to inner-service and N queries to database.
In total: N simultaneous requests emits 2 * N requests to inner systems.
With async_reduce
if client performs N simultaneous requests web_server
performs one request to inner-service and one query to database.
In total: N simultaneous requests emit only 2 requests to inner systems.
See other real examples.
Similar coroutines determination
async_reduce(coroutine)
tries to detect similar coroutines by hashing
local variables bounded on call. It does not work correctly if:
- one of the arguments is not hashable
- coroutine function is a method of class with specific state (like ORM)
- coroutine function has closure to unhashable variable
You can disable auto-determination by setting custom key to argument ident
.
Use as decorator
Also library provide special decorator @async_reduceable()
, example:
from async_reduce import async_reduceable
@async_reduceable()
async def fetch_user_data(user_id: int) -> dict:
"""" Get user data from inner service """
url = 'http://inner-servicce/user/{}'.format(user_id)
return await http.get(url, timeout=10).json()
@web_server.router('/users/(\d+)')
async def handler_user_detail(request, user_id: int):
""" Handler for get detail information about user """
return await fetch_user_data(user_id)
Hooks
Library supports hooks. Add-on hooks:
- DebugHooks - print about all triggered hooks
- StatisticsOverallHooks - general statistics on the use of
async_reduce
- StatisticsDetailHooks - like
StatisticsOverallHooks
but detail statistics about allcoroutine
processed byasync_reduce
Example:
from async_reduce import AsyncReducer
from async_reduce.hooks import DebugHooks
# define custom async_reduce with hooks
async_reduce = AsyncReducer(hooks=DebugHooks())
async def handler_user_detail(request, user_id: int):
user_data = await async_reduce(fetch_user_data(user_id))
See more detail example in examples/example_hooks.py.
You can write custom hooks via inherit from BaseHooks.
Caveats
-
If single
coroutine
raises exceptions all aggregatedcoroutine
s will get same exception too -
If single
coroutine
is stuck all aggregatedcoroutine
s will stuck too. Limit execution time forcoroutine
and add retries (optional) to avoid it. -
Be careful when return mutable value from
coroutine
because single value will shared. Prefer to use non-mutable value as coroutine return.
Development
See DEVELOPMENT.md.
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