Currently I found that jetty / tomcat on Linux will have many CLOSE_WAIT on busy system especially your network is not in good condition.

These CLOSE_WAIT will disappear untill you stop the server. These CLOSE_WAIT will use up all of you tcp connection and hang up your web server. Many people claimed that is the bug of jvm. Although I have tried most java ver., the problem still exist.

Here is another dirty way to fix that issue... although it is not the best solution........
add the following lines to /etc/sysctl.conf

net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_keepalive_intvl = 2
net.ipv4.tcp_keepalive_probes = 2
net.ipv4.tcp_keepalive_time = 1800

And then execute

sysctl -p

or do a reboot