Thingworx Tomcat CPU usage 100%

Hi ,

My thingworx server(deployed in a virutal machine) beomce very slow suddenly today (it has running for months smoothly) .  Whatever action you made in the thingworx composer, will cause the cpu usage up to 100% and it's occupied by the tomcat process, the memory usage is 65%, that's fine.   

Meanwhile,  in the Monitor->connected users , I notice there're more than 100 Administrator users.  I didn't notice how many Administrators list there , but I'm sure only one Administrator connected when the cpu is 100%. (please check the attached picture).  I've tried to terminate the other connected Administrator, but they appear again constantly. 

I've tried to restart the tomcat and the VM , but it doesn't help. 

Any idea about it ? 

===Versions===

Thingworx 8.4.4 + Postgresql 10.x + Windows server 2016

========tomcat config======

-Dserver -Dd64
-XX:+UseG1GC
-Dfile.encoding=UTF-8
-Djava.library.path=C:\Tomcat 9.0\webapps\Thingworx\WEB-INF\extensions
-Dcatalina.home=C:\Tomcat 9.0
-Dcatalina.base=C:\Tomcat 9.0
-Djava.io.tmpdir=C:\Tomcat 9.0\temp
-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
-Djava.util.logging.config.file=C:\Tomcat 9.0\conf\logging.properties
-Xms5500m
-Xmx5500m
-XX:PermSize=64m
-XX:MaxPermSize=512m
-agentlib:jdwp=transport=dt_socket,address=1043,server=y,suspend=n

Regards,

Sean