cpp unix multithread socket blocking and non-blocking. What is blocking?

Question

At my multithread application I using AF_UNIX type of socket. Seems by default its blocking. The question is whats mean by "blocking"? Is it block the thread when it execute the ::recv or ::send calls or all threads on the application (like fgets do)?

If it block all threads/whole application, I guess need to use non-blocking sockets? If so, please, give the good example of how to set up AF_UNIX non-blocking socket and when need to set non-blocking mode (and how). How to ::recv ? thanks.

Answer 1

Blocking calls make the thread wait for the operation to complete. Use them when your thread cannot continue before the operation has completed, for example due to the data dependency on the input being received.

Non-blocking calls return as soon as the information is buffered for transmission, or the read operation is initiated. Use them when there are no data dependencies.

In general, blocking always means "blocks the current thread", not "block all threads in my process.

Answer 2

It only blocks the thread that makes the recv call.