I have this twemproxy_sentinel setup that uses their default port 22122 as entry and forwards the requests to underlying redis servers running on port 6380, 6381.
Every now and then, the port 22122 becomes unavailable. Thus clients using the redis would not be able to connect. telnet to it would close instantly. All I needed to do was to /etc/init.d/nutcracker restart and things would be back to normal. All along, the sentinel and redis services are working. Only the twemproxy seems to get cut off. Before the time of restart, the nutcracker service is still running (ps would show it's running). The logs do not show any indication of things failing.
I'm not sure why this happens and tried to dig through the logs of both the redis servers, redis sentinel and twemproxy logs. I also tried looking into /var/log/messages and tried to ensure file-max won't be blocking the # of ports being opened.
Wonder where I can start to look into why things would go down.
Realized I've overlooked that max-files doesn't necessarily allows nutcracker to use those ports but merely allows the system to use so many ports. It is back to normal after actually enabling nutcracker to open more ports.