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bpo-32403: Faster date and datetime constructors#4993

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abalkin merged 6 commits into
python:masterfrom
pganssle:faster_datetime_constructors
Jan 16, 2018
Merged

bpo-32403: Faster date and datetime constructors#4993
abalkin merged 6 commits into
python:masterfrom
pganssle:faster_datetime_constructors

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@pganssle

@pganssle pganssle commented Dec 23, 2017 •
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This fixes bpo-32403 and bpo-32404. The first one is a performance enhancement, the second is a bugfix.

Using this script to benchmark the alternate constructors, I see significant improvements in speed across the board (note that since the subclasses don't take the fast path, they are a reasonable proxy for the speed from before this patch). You can see the results on my laptop (using the debug build, not the profiling optimized build) below:

Running with N = 10000, k=20
                   |           datetime           |       DateTimeSubclass       
=================================================================================
constructor        |  1416.5  [1463.9 (±71) ns]   |  1494.8  [1569.2 (±119) ns]  
fromordinal        |  1081.5  [1117.2 (±24) ns]   |  2180.7  [2357.3 (±279) ns]  
fromisoformat      |   928.8   [962.5 (±34) ns]   |  2834.8  [3179.7 (±281) ns]  
fromtimestamp      |  1504.3  [1600.9 (±63) ns]   |  3625.1  [3869.6 (±280) ns]  
utcfromtimestamp   |  1178.6  [1281.2 (±172) ns]  |  3242.6  [3445.0 (±205) ns]  
combine            |  1060.1  [1111.0 (±73) ns]   |  2808.7  [3013.0 (±236) ns]  
now                |  1219.3  [1325.0 (±216) ns]  |  3625.5  [3892.7 (±300) ns]  
today              |  4868.5  [5261.0 (±565) ns]  |  7189.5  [7663.0 (±436) ns]  
=================================================================================
                   |             date             |         DateSubclass         
=================================================================================
constructor        |  974.5   [1010.1 (±39) ns]   |  1114.7  [1298.8 (±229) ns]  
fromordinal        |  1059.7  [1109.4 (±59) ns]   |  1923.1  [2258.8 (±375) ns]  
fromisoformat      |  817.5   [905.1 (±123) ns]   |  1734.1  [2160.8 (±542) ns]  
fromtimestamp      |  1285.4  [1484.7 (±378) ns]  |  2363.6  [3038.6 (±783) ns]  
today              |  4551.7  [4976.6 (±584) ns]  |  5828.9  [6883.9 (±934) ns]  
=================================================================================

For comparision, here is the same script run against master:

Running with N = 10000, k=20
                   |           datetime           |       DateTimeSubclass       
=================================================================================
constructor        |  1335.9  [1350.3 (±24) ns]   |  1406.0  [1426.9 (±15) ns]   
fromordinal        |  1905.0  [1948.3 (±42) ns]   |  2011.5  [2055.4 (±32) ns]   
fromisoformat      |   918.1   [929.3 (±6) ns]    |  2660.8  [2707.7 (±25) ns]   
fromtimestamp      |  1570.1  [1611.8 (±28) ns]   |  1732.1  [1766.3 (±30) ns]   
utcfromtimestamp   |  1202.7  [1234.5 (±18) ns]   |  1334.9  [1371.7 (±26) ns]   
combine            |  2584.9  [2626.3 (±22) ns]   |  2722.8  [2759.8 (±25) ns]   
now                |   1317.2  [1338.2 (±9) ns]   |  1509.7  [1563.7 (±24) ns]   
today              |  5027.1  [5096.9 (±71) ns]   |  5237.6  [5334.9 (±73) ns]   
=================================================================================
                   |             date             |         DateSubclass         
=================================================================================
constructor        |   912.8   [928.8 (±15) ns]   |   996.4   [1003.9 (±7) ns]   
fromordinal        |  1662.9  [1706.4 (±40) ns]   |  1773.6  [1820.7 (±41) ns]   
fromisoformat      |   818.5   [829.0 (±9) ns]    |  1630.0  [1743.3 (±289) ns]  
fromtimestamp      |  2155.2  [2213.4 (±41) ns]   |  2321.9  [2486.9 (±590) ns]  
today              |  5502.0  [5624.6 (±76) ns]   |  5679.8  [5845.4 (±445) ns]  
=================================================================================

https://bugs.python.org/issue32403

@bedevere-bot

bedevere-bot commented Jan 12, 2018

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A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

@abalkin abalkin self-assigned this Jan 12, 2018
@pganssle pganssle force-pushed the faster_datetime_constructors branch from 6c6115c to 92ac0c4 Compare January 13, 2018 17:36
@pganssle pganssle force-pushed the faster_datetime_constructors branch from 92ac0c4 to b438cbe Compare January 13, 2018 17:39
@pganssle

pganssle commented Jan 13, 2018

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@abalkin I believe I fixed the style issues.

@abalkin abalkin merged commit 9f1b7b9 into python:master Jan 16, 2018
@pganssle pganssle mentioned this pull request Feb 22, 2018
Merged
@pganssle pganssle deleted the faster_datetime_constructors branch October 25, 2018 14:29
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