Just wait until they figure out how to use arena/stack-based memory.
I have been debugging that problem for some time. The charts in the article are quite similar to the ones I got when I initially came across the problem.
Wonder how many threads does their process have? and how many cores on the machine?
There are environment variables that can adjust the behavior of malloc. They should try setting MALLOC_ARENA_MAX=4 and see if the memory usage goes down.