Simon Willison’s Weblog

Items tagged performance, python

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Introducing the PyPy 1.2 release. It’s been a long time coming, but 1.2 is the first PyPy release to ship with a Just-in-Time compiler! Performance looks pretty impressive. # 12th March 2010, 11:54 pm

Is johnny-cache for you? “Using Johnny is really adopting a particular caching strategy. This strategy isn’t always a win; it can impact performance negatively”—but for a high percentage of Django sites there’s a very good chance it will be a net bonus. # 2nd March 2010, 11:44 am

Johnny Cache. Clever twist on ORM-level caching for Django. Johnny Cache (great name) monkey-patches Django’s QuerySet classes and caches the result of every single SELECT query in memcached with an infinite expiry time. The cache key includes a “generation” ID for each dependent database table, and the generation is changed every single time a table is updated. For apps with infrequent writes, this strategy should work really well—but if a popular table is being updated constantly the cache will be all but useless. Impressively, the system is transaction-aware—cache entries created during a transaction are held in local memory and only pushed to memcached should the transaction complete successfully. # 28th February 2010, 10:55 pm

Reexamining Python 3 Text I/O. Python 3.1’s IO performance is a huge improvement over 3.0, but still considerably slower than 2.6. It turns out it’s all to do with Python 3’s unicode support: When you read a file in to a string, you’re asking Python to decode the bytes in to UTF-8 (the new default encoding) at the same time. If you open the file in binary mode Python 3 will read raw bytes in to a bytestring instead, avoiding the conversion overhead and performing only 4% slower than the equivalent code in Python 2.6.4. # 28th January 2010, 1:28 pm

Why I like Redis

I’ve been getting a lot of useful work done with Redis recently.

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What’s New In Python 3.1. Lots of stuff, but the best bits are an ordered dictionary type (congrats, Armin), a Counter class for counting unique items in an iterable (I do this on an almost daily basis) and a bunch of performance improvements including a rewrite of the Python 3.0 IO system in C. # 28th June 2009, 3:02 pm

Django tip: Caching and two-phased template rendering. Neat trick for expensive pages which can be mostly cached with the exception of the “logged in as” bit—run them through the template system twice, caching the intermediary generated template. # 19th May 2009, 1:34 am

ProjectPlan—unladen-swallow. A branch of Python 2.6 aiming to radically improve performance (the target is a 5x improvement), by compiling Python to machine code using LLVM’s JIT engine. I think this is a Google 20% time project (or maybe not, see the comments). An early version without LLVM is already available for download. # 30th March 2009, 10:09 am

simplejson 2.0.1. Python’s simplejson JSON library got a whole lot faster while I wasn’t looking. # 1st October 2008, 10:55 pm