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str_repeat performance

php.internals

[ ]

3 years ago

Hello internals!

I have noted some strange points about `str_repeat` performance. It looks
like the lesser `$times` argument is, the bigger is execution time (only if
we consider big numbers).

For example, `str_repeat('%d ', 12500);` is a lot slower than
`str_repeat('%d ', 1250000)`.

First case (slow one):
https://3v4l.org/ZAoGi

Second case (fast one):
https://3v4l.org/YIdQM

Best regards,
Yevhen

Christoph Becker

3 years ago

On 10.09.2022 at 14:19, Eugene Sidelnyk wrote:

> I have noted some strange points about `str_repeat` performance. It looks
> like the lesser `$times` argument is, the bigger is execution time (only if
> we consider big numbers).
>
> For example, `str_repeat('%d ', 12500);` is a lot slower than
> `str_repeat('%d ', 1250000)`.
>
> First case (slow one):
> https://3v4l.org/ZAoGi
>
> Second case (fast one):
> https://3v4l.org/YIdQM

It seems you have misinterpreted the results.  4.792213439941406E-5 is
certainly much smaller than 0.013129949569702148, for instance.

--
Christoph M. Becker

[ ]

3 years ago

Oh, yes. Sorry for that.

Thanks for pointing out.

On Sat, Sep 10, 2022 at 3:23 PM Christoph M. Becker <cmbecker69@gmx.de>
wrote:

Hans Henrik Bergan

3 years ago

maybe you'll find
$t=microtime(true) - $startTime;
var_dump($t,number_format($t,10));

interesting, https://3v4l.org/Ejia3

On Sat, 10 Sept 2022 at 17:11, Eugene Sidelnyk <zsidelnik@gmail.com> wrote: