[intellij-idea] How can I give the Intellij compiler more heap space?

I like to share a revelation that I had. When you build a project, Intellij Idea runs a java process that resides in its core(ex: C:\Program Files\JetBrains\IntelliJ IDEA 2020.3\jbr\bin). The "build process heap size", as mentioned by many others, changes the heap size of this java process. However, the main java process is triggered later by the Idea's java process, hence have different VM arguments. I noticed that the max heap size of this process is 1/3 of the Idea's java process, while min heap is the half of max(1/6). To round up:

When you set 9g heap on "build process heap size" the actual heap size for the compiler is max 3g and min 1,5g. And no need for restart is neccessary.

PS: tested on version 2020.3