[Vm-dev] Object basicNew vs object shallowCopy

[Denis Kudriashov]

Hi.

I compared performance between object instantiation and object cloning. I
was wondering that instantiation almost twice faster than clone (primitive
70 vs 148).

Could you explain why it like that and could it be improved?

I was think that new object construction is much complex because it
requires to fill all object fields (header structure and etc).
And I was think that copy is just simple function like memcpy which just
copy bytes without any logic.

Here is my code:

object := Object new.
3 timesRepeat: [ Smalltalk garbageCollect ].
result1 := [ Object basicNew ] benchFor: 10 seconds.
3 timesRepeat: [ Smalltalk garbageCollect ].
result2 := [ object shallowCopy ] benchFor: 10 seconds.
{result1. result2}.
 "an Array(a BenchmarkResult(518,021,045 iterations in 10 seconds 2
milliseconds. 51,791,746 per second) a BenchmarkResult(302,807,253
iterations in 10 seconds 4 milliseconds. 30,268,618 per second))"

(I run it on latest Pharo on Mac SpurVM)

Best regards,
Denis
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