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faster Hash#except
Reported by Grant Hollingworth | June 10th, 2008 @ 05:02 PM
The current version of Hash#except uses include?, which is incredibly slow for a long list of keys.
This patch is based on a similar one for Merb. The Merb ticket includes benchmarks.
Comments and changes to this ticket
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Jeremy Kemper June 10th, 2008 @ 10:24 PM
- State changed from “new” to “open”
- Assigned user set to “Jeremy Kemper”
It already uses Set#include?, not Array#include?, so the benchmark is not equivalent.
Could you base a patch off the recent change made to Hash#slice?
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Grant Hollingworth June 11th, 2008 @ 04:49 AM
Okay, updated benchmarks:
except: small hash, 100 000 times
user system total real
except_reject 1.250000 0.010000 1.260000 ( 1.318881)
except_each 0.440000 0.000000 0.440000 ( 0.454850)
except: small hash, 100 000 times
user system total real
except_reject! 1.310000 0.020000 1.330000 ( 1.358561)
except_each! 0.150000 0.000000 0.150000 ( 0.155681)
big hash, 1000 times
user system total real
except_reject 6.550000 0.050000 6.600000 ( 6.696907)
except_each 1.720000 0.020000 1.740000 ( 1.780731)
big hash, 1000 times
user system total real
except_reject! 8.710000 0.100000 8.810000 ( 9.683930)
except_each! 0.080000 0.000000 0.080000 ( 0.105305)
I changed the keys from a Set to an Array, like in Hash#slice. Is that what you meant?
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Grant Hollingworth June 11th, 2008 @ 04:54 AM
- no changes were found...
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Repository June 11th, 2008 @ 08:47 AM
- State changed from “open” to “resolved”
(from [a797375c99efc88ee1438925cdc016305c66166c]) Performance: speed up Hash#except. [#382 state:resolved]
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Repository June 11th, 2008 @ 08:47 AM
(from [634e462a0b70ddae2f21dbddddd07e7b340bb69c]) Performance: speed up Hash#except. [#382 state:resolved]
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Mislav September 13th, 2008 @ 07:38 PM
- Tag set to “activesupport, core_ext, patch, tested”
This performance optimization breaks because it's using "clone" instead of "dup".
Consider these scenarios which are valid, but which both fail now:
obj1.freeze obj2 = obj1.except(...) # Mocha expectations obj1.expects(:delete).never obj2 = obj1.except(...)Using "dup" in place of "clone" solves both problems. Patch attached
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Grant Hollingworth
Jeremy Kemper
Mislav
Repository