NodeJS cache mysql data whith clustering enabled

I want to cache data that I got from my MySQL DB and for this I am currently storing the data in an object.

Before querying the database, I check if the needed data exists in the meantioned object or not. If not, I will query and insert it.

This works quiet well and my webserver is now just fetching the data once and reuses it.

My concern is now: Do I have to think of concurrent writes/reads for such data structures that lay in the object, when using nodejs's clustering feature?