OpenEuphoria

Re: allocate() and free()

• Posted by Aku <aku at inbox.as> Dec 02, 2000
• 517 views

I have made a program in VB that free memory that do not used by the
operating system. I use this code:

 a = space(10485760)  ' Allocate 10 MB of memory for variable 'a'
                      ' with spaces.
 '-------- the free memory decreases...
 a = ""               ' Free that 10 MB.
 '-------- ...then increases again.


I tried run this in Euphoria:

object a
? getc(0)
a = repeat(' ', 10485760)
? getc(0)
a = ""
? getc(0)


And this is a test:

object a
? getc(0)                    -- Here, my free memory: 110 MB
a = repeat(' ', 10485760)
? getc(0)                    -- Here, my free memory:  30 MB
                             -- [ repeat(' ', 10485760) uses 80 MB
                             --   of memory!!! ]
a = ""
? getc(0)                    -- Here, my free memory is STILL 30 MB!


I can free memory that is used in VB, why not in Euphoria?

______________________________________________________________________
R> free() does not give memory back to the operating
R> system. It simply puts it into a pool of free memory
R> that's controlled by Euphoria. It will be used by future
R> calls to allocate().

R> When the pool is exhausted, allocate() will get
R> more memory from the operating system, but
R> free() will never give it back.

R> I don't know of any language that gives
R> heap space back to the operating system.
R> It would be a tricky business, since you can
R> theoretically only give back space at the end
R> of the heap, not an arbitrary piece in the middle
R> somewhere.

R> In Windows, this is all virtual memory anyway.
R> The operating system can swap out pages
R> of memory that aren't being actively used,
R> to make room for active programs to run.

R> Regards,
R>    Rob Craig
R>    Rapid Deployment Software
R>    http://www.RapidEuphoria.com