Have you ever used non-blocking socket connection mode?

Yes, non-blocking mode for socket connections is often used when implementing asynchronous data processing or working with multiple connections simultaneously without creating a separate thread for each.

For example, in network servers or clients, where it is important not to block program execution while waiting for data, the socket is set to non-blocking mode. Then, read or write operations return immediately if data is unavailable, allowing the program to continue executing and check the status later.

In Go, this can be done using the syscall package or by using ready-made abstractions, such as netpoll or libraries for asynchronous input-output.

An example of setting non-blocking mode (simplified):

conn, _ := net.Dial("tcp", "example.com:80")

// Get the file descriptor
fd := conn.(*net.TCPConn).File()

// Set non-blocking mode
syscall.SetNonblock(int(fd.Fd()), true)

// Now read/write operations will not block

This allows efficient handling of multiple connections within a single thread.