Re: Memory allocation strategy

[Jon Paris <jon.paris@xxxxxxxxxxxxxx>]

On Jan 7, 2011, at 9:39 AM, rpg400-l-request@xxxxxxxxxxxx wrote:

> Strategy 2: I get one "big" block of memory and only do a reallocation if the data doesn't fit. (more work on my side)
>
> Doesn't the system do strategy 2 under the hood already? If I allocate 100 bytes the system probably allocates a page (or so) and not only 100 bytes. So a realloc should not trigger another allocation of a whole page.?!


I'm not sure why you need to do "work". As you surmise if you do a realloc the system will attempt to add additional memory to the end of the currently allocated block. If that is not possible (due to other allocations) then it will obtain an alternate allocation of sufficient size and copy the data from your existing allocation to the new one. This is why realloc returns a pointer - because the reallocated space may not be in the same location as the original. 

Jon Paris

www.Partner400.com
www.SystemiDeveloper.com