Singular

I'm struggling with a memory clean up/possible memory leak problem. Calling simple code like

builds up (variable) memory (I'm checking memory(0) and also direct system output coincides with this observation), although I would expect that after "kill r" everything is cleaned up (there are no further variables and processes defined). I realized it since I'm calling code like that a lot of times inside the same (c++) session. It seems to me that memory is lost whenever something is printed (output and info/warning messages). My question though is two-fold:
Is this actually a bug in the code or I'm I forgetting to clean up something? I'm mainly interested to have this properly working through the c++ interface. (I'm using interpreter functions directly from within c++, like iiAllStart), the same memory loss happens also happens when called from the singular binary.
Or is there a way to reset the whole interpreter environment from within c++ without a full restart?

(If you're interested: I'm actually building a simple Singular interface for Mathematica via its LibraryLink function to have fast interaction with Singular. Everything except from this memory problem works like a beauty.)

There several things still taking memory legally:
- standard.lib is always loaded (see listvar(proc))
- the kernel introduces some variables (Top, ZZ, QQ, etc.)
- polynomials rings over ZZ/p (for p<2^15) create 2 tables of size 2*p bytes
which is cached for the next ring creation
- the last output is cached (to be accessed via _) -
this cache is cleared, if the value depends on a ring and the ring is killed.

If I understand correctly theses things don't grow indefinitely (i.e. once they are initialized they stay more or less the same size depending on their current value), so that's not a problem for me.
To illustrate where I have memory building up consider the following code:

Running this piece of code several times inside the same session expands the used memory after every repetition. Since I run code like that a lot of times in the same session I eventually run out of memory. One observation that I made is that there is no memory increase if I drop the constant 'a' in the ring definition. I also checked out other examples and I couldn't not find a pattern in which cases there is memory building up.

The example you provide does not have a memory leak
in the current (development) version of Singular

Awesome, I just pulled the newest version and it indeed works nicely. Thanks a lot!