Proxy produces the following error message: Caused by: java.io.IOException: Too many open files

Issue/Introduction:

While active, the proxy Agent can encounter an issue that causes a java exception similar to:

Critical error: Selector caught an exception:
java.lang.RuntimeException: This error should have been handled already
at com.uc4.proxy.Server.proxySocketError(Unknown Source)
at com.uc4.proxy.Server$3.socketError(Unknown Source)
at com.uc4.proxy.nbio.Acceptor.handleAccept(Unknown Source)
at com.uc4.proxy.nbio.SelectorThread.run(Unknown Source)
at com.uc4.proxy.nbio.SelectorThread.access$000(Unknown Source)
at com.uc4.proxy.nbio.SelectorThread$1.run(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.io.IOException: Too many open files
at sun.nio.ch.ServerSocketChannelImpl.accept0(Native Method)
at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:422)
at sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:250)

Cause:

This is caused by improper handling of new files being opened when reaching an OS-level maximum.

Environment:

Release:
Component: APROXY

Resolution:

As a workaround, you can stop the Proxy and set the ulimit for the system the proxy resides on to unlimited.

Additionally, the issue was found and fixed with:

Proxy 3.0.1 in Proxy released 05-20-2019

Hotfix-Description: Proxy aborts when the process file descriptor limit is reached.

Proxy aborts with JVM IOException when the process file descriptor limit is reached.