Re: Optimize memory allocation code

On Fri, Sep 25, 2020 at 7:32 PM Li Japin <japinli(at)hotmail(dot)com> wrote:
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>
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> > On Sep 26, 2020, at 8:09 AM, Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > On Sat, Sep 26, 2020 at 12:14 AM Li Japin <japinli(at)hotmail(dot)com> wrote:
> >>
> >> Hi, hackers!
> >>
> >> I find the palloc0() is similar to the palloc(), we can use palloc() inside palloc0()
> >> to allocate space, thereby I think we can reduce duplication of code.
> >
> > The code is duplicated on purpose. There's a comment at the beginning
> > that mentions it:
> >
> > /* duplicates MemoryContextAllocZero to avoid increased overhead */
> >
> > Same for MemoryContextAllocZero() itself.
>
> Thanks! How big is this overhead? Is there any way I can test it？

Profiler. For example, oprofile. In hot areas of the code (memory
allocation is very hot), profiling is the first step.

merlin