[Python-Dev] PEP 550 v4: Decimal examples and performance (original) (raw)

Stefan Krah stefan at bytereef.org
Sun Aug 27 06:39:42 EDT 2017

On Sat, Aug 26, 2017 at 12:21:44PM -0400, Yury Selivanov wrote:

On Sat, Aug 26, 2017 at 7:45 AM, Stefan Krah <stefan at bytereef.org> wrote: >> This generic caching approach is similar to what the current C >> implementation of decimal does to cache the the current decimal >> context, and has similar performance characteristics. > > I think it'll work, but can we agree on hard numbers like max 2% slowdown > for the non-threaded case and 4% for applications that only use threads?

I'd be very surprised if wee see any noticeable slowdown at all. The way ContextVars will implement caching is very similar to the trick you use now.

I'd also be surprised, but what do we do if the PEP is accepted and for some yet unknown reason the implementation turns out to be 12-15% slower?

The slowdown related to the module-state/heap-type PEPs wasn't immediately obvious either; it would be nice to have actual figures before the PEP is accepted.

Stefan Krah

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