We're testing MongoDB 3.2 for a use case that have many collections in mongodb. We've script that creates 100K collections in single database at a time.

Case 1: We tried to create these collections with open files=64000(default set in mongod init script)

Result 1: The mongod stopped with too many open files when created collections reached to ~30K.

Case 2: Modified the mongod init script to set limit nofile 999999 999999.

Result 2: Created 100K collections without any error. Also applied indexes to these collections. No issues found.

Can we change the nofile value to 999999 permanently? How is it going to affect in production env?

What would be the good practice to avoid/mitigate the open files issues with WiredTiger with this such use case?

Any help would be appreciated.

Thanks in advance!