[fpc-pascal] Inclocked/declocked

Ryan Joseph ryan at thealchemistguild.com
Tue Sep 12 06:23:42 CEST 2017

> On Sep 12, 2017, at 2:35 AM, Sven Barth via fpc-pascal <fpc-pascal at lists.freepascal.org> wrote:
> I've rechecked and the thing is as follows:
> - the IncLocked call happens each time you assign a dynamic array to
> another dynamic array variable or a by-value parameter (this also
> includes being part of a record, but not a class instance or TP-style
> object)
> - the DecLocked call happens each time the array is cleared (as long as
> the reference count is > 0 this only means a decrement of the count)
> which happens if you assign Nil, assign a different array (the
> destination array is "cleared") or if the array variable goes out of scope
> The two routines are also used in context of Ansi- and UnicodeString
> variables as well as reference counted interfaces (aka COM-style
> interfaces).
> In contrast to what I wrote earlier the compiler does however not ensure
> a unique array if you only change an element, so given the following
> example:

I removed the dynamic arrays from the my code and replaced with static arrays which fixed the performance problem I was having.

It’s still not clear when this was being called (how could I track in the debugger?) but I consider this a pretty serious bug and I wouldn’t use dynamic arrays in high performance code.

If I had to guess I would say it was from SetLength but 16%? When I replaced with static arrays and used ReAllocMem instead this didn’t happen so what are those 2 functions doing to eat up so much CPU?

	Ryan Joseph

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