Yes, but this is very unusual. In a web server, you have pool of threads that can respond to incoming connections. When one is blocking, another is ready to go. All the transition are handled transparently by the kernel.
In node.js, each process used to be single thread. There's now a hokey threading model with limited shared memory areas.[1] Annoyingly, this is also Android's threading model.
Yes, but this is very unusual. In a web server, you have pool of threads that can respond to incoming connections. When one is blocking, another is ready to go. All the transition are handled transparently by the kernel.