Socket or port exhaustion when making fast RPC calls to bitcoin core

[casey]

JsonRpc(Transport(SocketError(Error { kind: TimedOut, message: "connection timed out" })))

This is due to using too many sockets or ports. Probably ports, specifically local ephemeral ports.

This is the rust-jsonrpc issue: apoelstra/rust-jsonrpc#67

Need to reuse the socket, or add hyper transport to rust-jsonrpc.

Update: I'm not actually sure what's going on here. We tried the socket-reusing version and it didn't help.

We should:

• Test again with the latest PR version
• Do a comparison with bitcoin-cli. If bitcoin-cli doesn't have this problem, then it's a good indication that the issue is in jsonrpc.

[veryordinally]

Potentially explore moving to https://github.com/paritytech/jsonrpsee

[raphjaph]

maybe try again with this fix: apoelstra/rust-jsonrpc#72