How does mongodb clear the memory it occupies

  mongodb, question

Recently, I learned to use mongodb, and found that it takes up a lot of memory. After searching online, I found that many of them use use admin. Db.runcommand ({closealldatabases: 1}) to clear memory, i found no such command in 3.0.图片描述

Is this command cancelled in 3.0 or is my method of opening incorrect? I have checked the manual and found no similar substitute command. Is this command still available in the latest version? If so, how should it be used?

I have also been studying mongodb recently. I recommend you a mongodb study material.http://www.hubwiz.com/course/54bdfcb188dba012b4b95c9c/