This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
This is actually an operating system issue. Linux treats everything as a file - if there are too many connections open on the machine, you'll get that message. Have your sys admin look at the max number of open file handles on the system to make sure it isn't set too low. Also, make sure you aren't opening system resources like Sockets and the such and failing to close them - poor programming practices can cause that error as well.