Solution to Blocking system call by worker thread in Node.js

Question

I recently learnt about user level threads and kernel level threads in Operating System book by tanenbaum. Since user level threads are handled by library packages and since had worked with node.js a bit, i concluded that node.js uses libuv for handling worker threads and hence uses user level threading.

But I wanted to know how node.js deals with the case when some worker thread makes a system call that is blocking and then the kernel will block the entire process even if some threads are capable of running.

Answer 1

But I wanted to know how node.js deals with the case when some worker thread makes a system call that is blocking and then the kernel will block the entire process even if some threads are capable of running.

This isn't what happens in a modern OS. Just because one thread in a process is reading/writing from the disk, the OS does NOT block the entire process from doing anything with its other threads.

Modern hardware uses DMA (Direct Memory Access) for reading/writing to disks precisely so that the CPU does not have to be blocked while a block of data is read from or written to a disk.