Read write lock for asyncio.
.. image:: https://github.com/aio-libs/aiorwlock/workflows/CI/badge.svg :target: https://github.com/aio-libs/aiorwlock/actions?query=workflow%3ACI .. image:: https://codecov.io/gh/aio-libs/aiorwlock/branch/master/graph/badge.svg :target: https://codecov.io/gh/aio-libs/aiorwlock .. image:: https://badges.gitter.im/Join%20Chat.svg :target: https://gitter.im/aio-libs/Lobby :alt: Chat on Gitter
Read write lock for asyncio_ . A RWLock
maintains a pair of associated
locks, one for read-only operations and one for writing. The read lock may be
held simultaneously by multiple reader tasks, so long as there are
no writers. The write lock is exclusive.
Whether or not a read-write lock will improve performance over the use of a mutual exclusion lock depends on the frequency that the data is read compared to being modified. For example, a collection that is initially populated with data and thereafter infrequently modified, while being frequently searched is an ideal candidate for the use of a read-write lock. However, if updates become frequent then the data spends most of its time being exclusively locked and there is little, if any increase in concurrency.
Implementation is almost direct port from this patch_.
Requires Python 3.5.3+
.. code:: python
import asyncio import aiorwlock
async def go(): rwlock = aiorwlock.RWLock()
# acquire reader lock, multiple coroutines allowed to hold the lock
async with rwlock.reader_lock:
print('inside reader lock')
await asyncio.sleep(0.1)
# acquire writer lock, only one coroutine can hold the lock
async with rwlock.writer_lock:
print('inside writer lock')
await asyncio.sleep(0.1)
loop = asyncio.get_event_loop() loop.run_until_complete(go())
By default RWLock
switches context on lock acquiring. That allows to
other waiting tasks get the lock even if task that holds the lock
doesn't contain context switches (await fut
statements).
The default behavior can be switched off by fast
argument:
RWLock(fast=True)
.
Long story short: lock is safe by default, but if you sure you have
context switches (await
, async with
, async for
or yield from
statements) inside locked code you may want to use fast=True
for
minor speedup.
TLA+ specification of aiorwlock
provided in this repository.
aiorwlock
is offered under the Apache 2 license.
.. _asyncio: http://docs.python.org/3.8/library/asyncio.html .. _patch: http://bugs.python.org/issue8800
1.3.0 (2022-1-18) ^^^^^^^^^^^^^^^^^^
loop
parameter from RWLock
constructor1.2.0 (2021-11-09) ^^^^^^^^^^^^^^^^^^
1.1.0 (2021-09-27) ^^^^^^^^^^^^^^^^^^
asyncio.sleep()
call, make the library forward
compatible with Python 3.101.0.0 (2020-12-32) ^^^^^^^^^^^^^^^^^^
Fix a bug with cancelation during acquire #170 (thanks @romasku)
Deprecate passing explicit loop
argument to RWLock
constructor
Deprecate creation of RWLock
instance outside of async function context
Minimal supported version is Python 3.6
The library works with Python 3.8 and Python 3.9 seamlessly
0.6.0 (2018-12-18) ^^^^^^^^^^^^^^^^^^
Wake up all readers after writer releases lock #60 (thanks @ranyixu)
Fixed Python 3.7 compatibility
Removed old yield from
syntax
Minimal supported version is Python 3.5.3
Removed support for none async context managers
0.5.0 (2017-12-03) ^^^^^^^^^^^^^^^^^^
Fix corner cases and deadlock when we upgrade lock from write to read #39
Use loop.create_future instead asyncio.Future if possible
0.4.0 (2015-09-20) ^^^^^^^^^^^^^^^^^^
Support Python 3.5 and async with
statement
rename .reader_lock
-> .reader
, .writer_lock
->
.writer
. Backward compatibility is preserved.
0.3.0 (2014-02-11) ^^^^^^^^^^^^^^^^^^
.locked
property0.2.0 (2014-02-09) ^^^^^^^^^^^^^^^^^^
.release()
non-coroutine0.1.0 (2014-12-22) ^^^^^^^^^^^^^^^^^^