socket buffer size could be increased

[chu11]

On very large clusters we've seen listeners lose packets (grep for port 2293 (8851 in hex) on /proc/net/udp).

The suspicion is that during large bursts of traffic the default socket buffer size is too small (typically 200k).

While games can be played with increasing the number of listener threads tweaking the heartbeat/up-down timeout, ultimately an increase in socket buffer size would surely help.