Exaeta

Please fix. My game is messed up because of this. :/

This can be reproduced like this: Make world in 18w16a, visit end, import to 1.13-pre1.

It seems to only apply to old terrain, newly generated terrain has endermem. Also, if a portal generates that area becomes able to spawn endermen.

I have linux too, I'm running linux mint with MATE and I don't have this issue.

This is probably related to the Garbage Collector.

Try these options:

-server -XX:+AggressiveOpts -XX:+UseConcMarkSweepGC -XX:MaxGCPauseMillis=10 -XX:ConcGCThreads=16 -XX:-CMSClassUnloadingEnabled -XX:+AggressiveOpts -XX:ThreadStackSize=2048k -XX:ObjectAlignmentInBytes=64

Also your Java version might help.

I don't think it should attack them (maybe poke them, but it shouldn't chase them)