I also have this issue. Percona 5.7.14-8 on Ubuntu Server 12.04. I’ve had it regularly before and the fix I put into place was based on this thread (adding a ulimit in systemd for a really high max files):
That has been in place for almost 3 months and now it’s appearing again during overnight backups on one of our servers. While I can still log into the server with the local mysql client, TCP connections are no longer available. We can’t use sockets because that has other issues with our software. I also just found this open bug ticket, though there’s no activity on it from the developers:
Any ideas? This is the second bug we have with Percona 5.7 that’s going unresolved.