… Is this a trick question? The object, provided by the library (net/http which is about as default as they come) sets “DefaultMaxIdleConnsPerHost” to 2. This is significant because if you finish a connection and you’ve got more than 2 idles, it slams that connection close. If you have a lot of simultaneous fast lived requests to the same IP (say a load balanced IP), your go programs will exhaust the ephemeral port list quickly. It’s one of the most common “gotchas” I see where Go programs work great in dev and blow themselves apart in prod.

https://dev.to/gkampitakis/http-connection-churn-in-go-34pl is a fairly decent write up.