Is there any way to Preload indexes to RAM on startup of mongodb

Hello everyone,
I am running a cron whose code is written in golang, and i am using mongoDb as database
There was 128GB Ram into my system in which DataBase is stored, and I am using different system for the code.
After the startup of Mongodb, when the cron runs for the first time it takes so much time to load indexes to ram which effects the overall time of it.
I have also added the indexes for some of the collections to improve the overall time of the query to execute, which does suits well when the Indexes are loaded to the RAM for that collection.

Is there any way to Preload indexes of all databases collections in RAM at the time of startup of Mongodb, for some warmup of database, so that it doesn’t takes time for executing the queries from db.

Can someone help me out to find the solution?

Maybe try running a “preload version of cron” before you start the “first cron” ?
the preload version only issues gets requests so that its related index will be cached in ram.

RAM is limited so the cache for index data is normally LRU.

I want some other alternative than this, like earlier there was a touch command which was valid in versions less than 4.2. Does mongodb has anything like this in recent versions?