R/C++/memory leaks

Ernest Turro wrote:

Dear all,
I have wrapped a C++ function in an R package. I allocate/ 
deallocate  memory using C++ 'new' and 'delete'. In order to allow  
user  interrupts without memory leaks I've moved all the delete  
statements  required after an interrupt to a separate C++ function  
freeMemory(),  which is called using on.exit() just before the .C 
() call.
I am concerned about the following. In square brackets you see  
R's  total virtual memory use (VIRT in `top`):
1) Load library and data [178MB] (if I run gc(), then [122MB])
2) Just before .C [223MB]
3) Just before freeing memory [325MB]
4) Just after freeing memory [288MB]
5) After running gc() [230MB]
So although the freeMemory function works (frees 37MB), R ends up   
using 100MB more after the function call than before it. ls()  
only  returns the data object so no new objects have been added to  
the  workspace.
Do any of you have any idea what could be eating this memory?
Many thanks,
Ernest
PS: it is not practical to use R_alloc et al because C++  
allocation/ deallocation involves constructors/destructors and  
because the C++  code is also compiled into a standalone binary (I  
would rather avoid  maintaining two separate versions).

Read the help page of gc(). You need to run it with reset=TRUE for
the usage to drop back to original. i.e. gc(reset=TRUE). gc() on its
own doesn't quite do what you think it would do.