We use Go for a soft realtime application (RTB), and it works well enough. We essentially have two performance issues, one being the particular database we use (which is not directly related to Go itself), the other one being GC pressure. Before Go 1.3, too many allocations were _very_ noticeable with GC pauses sometimes being close to 100ms (which is a problem when your maximum RTT is 100ms), but Go 1.3 improved things enormously. I'm confident things will get even better with Go 1.4.
When you're 90ms into your bid calc and Go pauses for 10ms STW you will loose all your connections and timeout your bids.
It's fine for basic stuff but if you want to really listen to full RTB bid stream and have real time responses you need pauseless GC to win. Or you have to budget for considerably less time to make a decision.
Also there are places in RTB where you have 10ms RTT and Go fails ought right in that situation at scale. :-)
