In fact, the mongod process is very much paralleled, which is usually good, but in my case, starts to eat all memory and from a large load and sometimes crashes. Need to limit the number of sarkerov (or thread pool, what's he got) to, say, more than 5 is never created and put the rest in turn. Can't find the setting.
And it turns out so much voraciously:

I would like to settle down.