https://en.wikipedia.org/wiki/Unix_domain_socket#:~:text=The....
Puma creates a `UnixServer` which is a ruby stdlib class, using the defaults, which is extending `UnixSocket` which is also using the defaults
https://github.com/puma/puma/blob/fba741b91780224a1db1c45664...
Those defaults are creating a socket of type `SOCK_STREAM`, which is a tcp socket
> SOCK_STREAM will create a stream socket. A stream socket provides a reliable, bidirectional, and connection-oriented communication channel between two processes. Data are carried using the Transmission Control Protocol (TCP).
https://github.com/ruby/ruby/blob/5124f9ac7513eb590c37717337...
You still have the tcp overhead when using a local unix socket with puma, but you do not have any network overhead.
UDS using SOCK_STREAM does not do that; ie, it is not using IPPROTO_TCP.
> SOCK_STREAM will create a stream socket. A stream socket provides a reliable, bidirectional, and connection-oriented communication channel between two processes. Data are carried using the Transmission Control Protocol (TCP).
> SOCK_DGRAM will create a datagram socket.[b] A Datagram socket does not guarantee reliability and is connectionless. As a result, the transmission is faster. Data are carried using the User Datagram Protocol (UDP).
> SOCK_RAW will create an Internet Protocol (IP) datagram socket. A Raw socket skips the TCP/UDP transport layer and sends the packets directly to the network layer.
I don't claim to be an expert, I just have a certain confidence that I'm able to comprehend words I read. It seems you can have 3 types of sockets, raw, udp, or tcp.
