ranger: Improve intsRanger performance #202
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This uses an indirection trick to avoid an allocation in intsRanger.Range call, signficantly improving its performance during iteration. The trick involves calling reflect.ValueOf on the address of the field instead of using its concrete value. This avoids an allocation performed by the Go runtime to convert the int value to an interface value. In order to use this trick, the interpretation of the 'i' field needed to be changed from "next index" to "previous index" and its initialization needed to be offset by -1. Following is the impact of this change in the relevant benchmark: name old time/op new time/op delta IntsRanger-4 61.0ns ± 2% 23.1ns ± 1% -62.12% (p=0.000 n=10+9) name old alloc/op new alloc/op delta IntsRanger-4 15.0B ± 0% 0.0B -100.00% (p=0.000 n=9+10) name old allocs/op new allocs/op delta IntsRanger-4 1.00 ± 0% 0.00 -100.00% (p=0.000 n=10+10)
sauerbraten
reviewed
Dec 15, 2022
|
Very cool, I think the new intsRanger code is still pretty easy to read, so am definitely gonna merge this. Thank you! |
This demonstrates function calling is cheaper than pipeline execution in the current implementation.
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This uses an indirection trick to avoid an allocation in intsRanger.Range call, signficantly improving its performance during iteration.
The trick involves calling reflect.ValueOf on the address of the field instead of using its concrete value. This avoids an allocation performed by the Go runtime to convert the int value to an interface value.
In order to use this trick, the interpretation of the 'i' field needed to be changed from "next index" to "previous index" and its initialization needed to be offset by -1.
Following is the impact of this change in the relevant benchmark:
Additionally, it adds a benchmark to assert custom renderer performance.
It's now possible to execute templates with guaranteed zero memory allocations (during execution) by using a combination of int and custom rangers and either simple field access or custom renderers.