Watching Server java.lang.Unsafe.park(Native Method)

Operator kicks a player, and when player tries to rejoin, the following starts to happen:

[18:21:14] [User Authenticator #6/INFO]: UUID of player Betterllcoolace is b57f2d7c-c567-433c-b452-fb73a066ee49
[18:21:28] [User Authenticator #7/INFO]: UUID of player Betterllcoolace is b57f2d7c-c567-433c-b452-fb73a066ee49
[18:21:45] [User Authenticator #8/INFO]: UUID of player PV__nRT is c2ba6410-3c27-4638-ada4-63c651330dd2
[18:21:52] [User Authenticator #9/INFO]: UUID of player Diensn is 60754b49-9900-485c-8bdb-73575f8b8b9f
[18:21:53] [User Authenticator #10/INFO]: UUID of player Betterllcoolace is b57f2d7c-c567-433c-b452-fb73a066ee49
[18:21:57] [User Authenticator #11/INFO]: UUID of player Diensn is 60754b49-9900-485c-8bdb-73575f8b8b9f
[18:22:09] [Server Watchdog/FATAL]: A single server tick took 60.01 seconds (should be max 0.05)
[18:22:09] [Server Watchdog/FATAL]: Considering it to be crashed, server will forcibly shutdown.
[18:22:09] [Server Watchdog/ERROR]: This crash report has been saved to: /home/rob/Desktop/server/snapshot/./crash-reports/crash-2019-03-15_18.22.09-server.txt

Player trying to join server is stuck on screen saying "Encrypting" before being Timed Out.