180k products are not a very big number . It sounds like the site loads too many products than it needs. There is no easy way to spot that, but if you has captured memory dumps before the site restarts then Application support should be able to look into it and provide some guidance 

@Quan Mai: I cannot thank you enough for taking the time to respond to our posts!

The issue was related to our custom products indexing job where we load the whole catalog to custom index it in FIND.

Using your tutorial here of traversing the catalog contributed in resolving the issue: https://leanpub.com/epicommercerecipes/read_sample 

This brings another question to my mind related to memory management. I understand there is an expiry time for VariantContent cached in the memory.

But shouldn't the memory forced to free these cached objects if it reaches its maximum capacity? I guess cached objects should have higher priority than any other objects in memory.

Thanks again for the help.

You are very welcome. 

Yes in theory asp.net will trim the cache if there is a memory pressure. However you might have setting that keep the threshold high (e.g the cache will not be trimmed until it reaches 95% ) and you might have auto heal rule that restarts the instance if it reaches, says, 90%. Is it the case?

if you are running Cms11+ and are using scheduled job you have a way to reduce cache time 

We turned off auto heal for troubleshooting this issue. The issue was still occuring.

Yes, we do use CMS 11.11.2. My understaning is contents loaded by schedule job have very short expiration time if I am not mistaken

I misread it a little bit, so you are trying to use the recipe to resolve the problem, not that it caused the problem :) . As long as you load content in batches AND you don't have too aggressive memory management thresholds (I would suggest to start with all default settings), it should be fine. 

And yes, CMS 11 allows you to reduce the caching time, as if you are indexing the content you just need them once, then discard.

Wait a second, why don't you have the blue badge below your name?

Do you need help with commerce certifiication?!! :)