Can Threads Share the same Client Socket?
Multiple threads can read and write to the same socket. Since everytime you accept, it shall extract the first connection on the queue of pending connections, create a new socket with the same socket properties and allocate a new file descriptor for that socket.
So only one thread per accepted connection.
If you are asking if you can do multiple write/read on an accepted connection, you will need locking features, hence loss of parallelism benefits. If you want to thread a long process and then write the result in the socket, use synchronization to write in the correct order.