How to control number of running worker processes for MongoDB?

Question

Well, as the question simply explains itself, let me clear it up little more.

I am running MongoDB primarily for read-only purposes at back-end. My crons do the writes and they don't really push it hard when they are triggered. Some updates, some new documents etc.

The thing is requests usually do not even hit the application level because of entire page caching handled within MemCached by Nginx. So the application doesn't query database for another hour per page.

But so far as I can see in my process list, there are 21 MongoDB worker processes that are using none of the CPU but reasonably large amount of memory because of the previous queries.

I checked the configuration settings and googled around but couldn't find any answer.. So, is there any way to limit those processes or at least to tell MongoDB reduce/empty its memory usage after a while?

Answer 1

Workers are using for talking to config server and other replica as well apart from just serving user request. This is documented in here.

we can limit net.maxIncomingConnections as par recommendation on this page to limit the number of workers processing user request. But this should be used with precaution as setting this number too low and then sending more concurrent calls will result in some calls being queued.