It would be nice if libcurl had an option to set the maximum connection lifetime -- i.e. the maximum length of time a connection in the cache could be considered reusable (after which the old connection to the server would be closed and a new one established upon receiving a request following the expiration of the lifetime).
Such a setting is useful in situations where the HTTP service may have moved to a new IP address, but the prior server cannot or should not close the current connection (due to sudden power loss, lack of its own connection timeout mechanism, or where a race condition causes the server's FIN or RST packet to arrive after the client has already sent a pending request).
Yes, I can see how this can be useful. I don't have any plans to work on this myself. I'm moving this entry over to the Feature Request tracker as this is not a bug.