Looks like your operating system is running out of open file descriptors, this problem commonly comes because of operating system limitation and not application.
You need to determine the following:
What is the current ulimit set at?
How fast are the file handles being taken?
Also take a thread dump, after analyzing the above collected data, if you need to increase the limit for number of open file descriptors, you can either set the ulimit parameter in server.sh file(depends on the IS version) or run the following command on operating system which needs root access, so that might be done by System Administrator:
“ulimit -n nnnn (Where is nnnn is the desired number of open files)”
BTW which OS are you using ?