Re: Slowdown around 5.0.5-dev-0

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Oct 18, 2015 1:40 PM, "Sebastian Gniazdowski" <sgniazdowski@xxxxxxxxx>
wrote:
>
> On 18 October 2015 at 18:19, Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>
wrote:
> >
> > I'm strongly inclined to think that's more likely an artifact of the
> > testing method than of the test itself have you tried running the
> > tests in the opposite order?
>
> It starts new zsh process – the one in "$current_zsh" variable – and
> feeds it with the same script file, giving in arguments pid of main
> Zsh, name of tested Zsh and name of test function to run. This should
> imply full separation of the tests. That's why order shouldn't matter.

Sorry, I didn't mean order of zsh versions, I meant did you try doing
array_test before string_test within each version.

> You are quite right that the memory usage isn't "high from the
> beginning". It starts from 41 MB, goes to 164, 279, etc. in quite
> controlled way. Previous version of the script awaited 3 seconds
> before doing first check, that's why it started from values of 100 MB,
> and I rather misinterpreted this. How to interpret these still high
> values is now open.

String is stored as one contiguous block of bytes, so each time it exceeds
the size of the current heap block an entire new large-enough block is
allocated, and no previous block can never be re-used because the string
never shrinks.

> Tried a new test function:
>
> Its memory usage is low for all Zsh versions: ~2.5 MB, (e.g. 2.7, 2.9,
> 2.8, 2.6, 2.9, 2.8, 2.6, 2.9, 2.9, 2.8).

For functions the test would also need to compare run time / CPU usage - I
would not expect memory usage to be interesting unless the function
declared locals.