I have two servers running 12.04.4 and 14.04.1 respectively. Both have nginx (port 80) and a Java process (port 8080).

As expected, the lsof output for the Java process on the 12.04 machine shows a couple of established connections for port 8080 (e.g. TCP 127.0.0.1:8080->127.0.0.1:58067 (ESTABLISHED))

The 14.04 machine however does not. It only shows the listening port (TCP *:8080 (LISTEN)). I'm sure there are active connections though (confirmed by access logs, Java process status output, etc).

What has changed from 12.04 to result in this behavior? Can this change be the cause for the "Too many open files" errors I'm getting since moving from 12.04 to 14.04?

12.04:

$ dpkg -l lsof linux-image-virtual openjdk-7-jre nginx
||/ Name                                        Version
+++-===========================================-===========================================
ii  linux-image-virtual                         3.2.0.59.70
ii  lsof                                        4.81.dfsg.1-1build1
ii  nginx                                       1.6.1-1~precise
ii  openjdk-7-jre                               7u65-2.5.1-4ubuntu1~0.12.04.1

14.04:

$ dpkg -l lsof linux-image-virtual openjdk-7-jre nginx-full
||/ Name                                  Version                 Architecture            Description
+++-=====================================-=======================-=======================
ii  linux-image-virtual                   3.13.0.32.38            amd64
ii  lsof                                  4.86+dfsg-1ubuntu2      amd64
ii  nginx-full                            1.4.6-1ubuntu3          amd64
ii  openjdk-7-jre:amd64                   7u65-2.5.1-4ubuntu1~0.1 amd64