[AWS]EC2 Instance, why the jvm memory is initiallized when the instance is rebooted

Unlike regular computer, server computer runs 24 hours a day.

In detail, it runs until shutdown, not 24 hours a day

In this case, memory is stacked in server

For example,

Even if user who has accessed my web site leaves my web site,

the object used by accessed user was still remain 

so memory is stacked

java's garbage collector removes object that considerd to be less likely to usable

In other words, objects that have not been removed are considerd to be usabled 

When a lot of objects are accumulated like this, memory is accumulated on the server because the object must be managed by memory.

In this case, memory is initialized by reboot the server

I'll explain why memory was initialized by comparing it to a real computer use case

If you reboot the computer with the game running, the computer will start up with the game closed.

Likewise, If you reboot the server, object was removed and so memory is initialized

But if you use this way for manage server, it is not recommended  

because rebooting the server causes inconvenience to users

For cloud environment, you can use two server

so if one breaks down by memory error, you can concentrate traffic to another server

and replace the break down server with a new one 

This way, you can continue to operate normally without the server going down.