Comment by oasisbob
4 hours ago
Open TCP connections can also be wildly cheap and efficient - Apple Push Notifications (APNS) and Android's push systems maintain open TCP connections to just about every mobile device on this planet.
An open connection is just a bit of state on either end. The C10K problem has been solved for ages.
Anyone remember consuming Twitter hoses back in the day? Those were also long-lived persistent connections for efficiency reasons.
Not only this but the spec explictly allows provider-terminated connections followed by a 429 with a respected "Retry-After" if you want to definitely kick "slow" feeds. This combined with HTTP2/3 multiplexing makes holding feeds open pretty cheap.