Mongo DB - Limit memory usage

[Kaushik G]

Hi Team,

We are using mongo DB in a single node. I understand that this is not MongoDB is intended to do. But due to the sophistication of mongo's querying and other architectural/ business reasons we have chosen MongoDB. We are facing an issue now. We would be happy to get it resolved with your help.

Problem:-

We have to limit the memory utilisation of MongoDB.

ENV: Windows

Version: 3.2

What we know:-

1. MongoDB utilises as much memory as possible to give a better performance

2. When memory utilisation reaches a certain threshold percentage, MongoDB frees up the memory it holds

3. We are not able to see the memory utilisation of MongoDB service in Task Manager

We would be much obliged to hear from you. Thanks in advance.

Regards,

Kaushik

[Pravin Dwiwedi]

Kaushik, What issues you are facing?? Based on the issues there will be resolution. Also, in case of lower load/working set hardly you will see the RAM consumption by MongoDB  specially in case of WairedTiger. If you don't see high memory consumption then I don't think it should be an issue. In case of complex aggregation queries only RAM utilization would be very high otherwise MongoDB WiredTiger is very optimized for memory utilization. 

I am sure you are having WiredTiger Engine. In that case to some extent you can control the RAM using storage.wiredTiger.engineConfig.cacheSizeGB parameter in your Config File. this task is very critical task and before providing the value you will have to be aware of your working set.

Here you go for guidelines--

https://docs.mongodb.com/v3.2/reference/configuration-options/#storage.wiredTiger.engineConfig.cacheSizeGB

Regards

Pravin Dwiwedi