Sometimes agents disconnected

Sometimes my agents disconnected from controller.

I don’t know what’s going on, but I checked the controller server resources and there seems to be something unusual.

first, high CPU %

second, high memory
controller server is using 16GB of RAM, Jenkins min/max heap size settings are both 8GB

thrid, GC time

fourth, Http mean times

I doubt this problem came from specific http request(/api/xml GET).

Is it the right direction for me to think like this?