DiskCache: Disk Backed Cache
DiskCache_ is an Apache2 licensed disk and file backed cache library, written
in pure-Python, and compatible with Django.
The cloud-based computing of 2016 puts a premium on memory. Gigabytes of empty space is left on disks as processes vie for memory. Among these processes is Memcached (and sometimes Redis) which is used as a cache. Wouldn’t it be nice to leverage empty disk space for caching?
Django is Python’s most popular web framework and ships with several caching backends. Unfortunately the file-based cache in Django is essentially broken. The culling method is random and large caches repeatedly scan a cache directory which slows linearly with growth. Can you really allow it to take sixty milliseconds to store a key in a cache with a thousand items?
- In Python, we can do better. And we can do it in pure-Python!
In : import pylibmc In : client = pylibmc.Client([‘127.0.0.1’], binary=True) In : client[b’key’] = b’value’ In : %timeit client[b’key’]
10000 loops, best of 3: 25.4 µs per loop
In : import diskcache as dc In : cache = dc.Cache(‘tmp’) In : cache[b’key’] = b’value’ In : %timeit cache[b’key’]
100000 loops, best of 3: 11.8 µs per loop
Note: Micro-benchmarks have their place but are not a substitute for real measurements. DiskCache offers cache benchmarks to defend its performance claims. Micro-optimizations are avoided but your mileage may vary.
DiskCache efficiently makes gigabytes of storage space available for caching. By leveraging rock-solid database libraries and memory-mapped files, cache performance can match and exceed industry-standard solutions. There’s no need for a C compiler or running another process. Performance is a feature and testing has 100% coverage with unit tests and hours of stress.
Does your company or website use
DiskCache? Send us a
<[email protected]> and let us know.
- Fully Documented
- Benchmark comparisons (alternatives, Django cache backends)
- 100% test coverage
- Hours of stress testing
- Performance matters
- Django compatible API
- Thread-safe and process-safe
- Supports multiple eviction policies (LRU and LFU included)
- Keys support “tag” metadata and eviction
- Developed on Python 2.7
- Tested on CPython 2.7, 3.4, 3.5 and PyPy
Installing DiskCache is simple with
$ pip install diskcache
You can access documentation in the interpreter with Python’s built-in help function::
from diskcache import Cache, FanoutCache, DjangoCache help(Cache) help(FanoutCache) help(DjangoCache)
For those wanting more details, this part of the documentation describes introduction, benchmarks, development, and API.
DiskCache Cache Benchmarks_
DiskCache DjangoCache Benchmarks_
DiskCache API Reference_
DiskCache Tutorial: http://www.grantjenks.com/docs/diskcache/tutorial.html
DiskCache Cache Benchmarks: http://www.grantjenks.com/docs/diskcache/cache-benchmarks.html
DiskCache DjangoCache Benchmarks: http://www.grantjenks.com/docs/diskcache/djangocache-benchmarks.html
DiskCache API Reference: http://www.grantjenks.com/docs/diskcache/api.html
DiskCache Development: http://www.grantjenks.com/docs/diskcache/development.html
Reference and Indices
DiskCache at PyPI_
DiskCache at GitHub_
DiskCache Issue Tracker_
DiskCache Documentation: http://www.grantjenks.com/docs/diskcache/
DiskCache at PyPI: https://pypi.python.org/pypi/diskcache/
DiskCache at GitHub: https://github.com/grantjenks/python-diskcache/
DiskCache Issue Tracker: https://github.com/grantjenks/python-diskcache/issues/
Copyright 2016 Grant Jenks
Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.