Why does open jdk use so much memory when doing an android build and why isn't it closed automatically when the build is done?

Since I've gone on to use 2018.3, every time I've done a build out to android, Open Jdk starts up and eats a minimum of 2.5G of Ram. But after the build is done it doesn't get closed or release any of the ram it's using. Unity it'self doesn't seem to be using it as it's not needed until a build and terminating the process doesn't crash unity or have any other effects on the system. So while I understand it being needed for an android build, I can't understand why it needs so much ram or why it's not killed off after it's finished? Would anybody mind explaining that for me? Thanks in advance!