cache/buffers growing constantly (2.4.20aa1)

Dear list,

I am constantly running a process creating child processes, running them for a while, then terminating, restarting and so on...
The process restarted over and over again is the same (same executable) the launching process doesn't stop.
Running this for a while (or increasing the number of "launchers" but keeping the launched process the same all the time lets the buffers/cache constantly grow up to the point where all memory is taken and the machine starts swapping...

Q:Is there any way to limit the cache/buffe usage? And, if yes, how?

Thanks for the help,

Immanuel