The more I think about it, the more I'm convinced of it.

The biggest selling point of Node folks has been the "single threaded, event driven" model, right? Unlike JavaScript, other languages work on a "blocking" basis i.e. you run a statement or command and the program "waits" until the I/O is complete. For example, you issue open('xyz.txt', 'rb').read() in python and the program waits or blocks until the underlying driver is able to read that whole text file (which could take arguably long time if said file is too large in size).

But with the Nodejs equivalent, you just issue the statement and then pass the "event handler" so that your program is never in the "waiting state". The whole premise of Node/JS event-callback is that "you don't call us, we will call you".

This is all nice in theory but if this were indeed true then Nodejs scripts should be blazing fast compared to Python and even Java considering that most programs we write are I/O heavy and 99% of time, they're just waiting for an input from a File/URI/User? If this event callback model indeed worked as effectively as claimed, Node would have been the numero one and only language being used today?

I think I'm starting to understand why that isn't the case. This whole "single threaded, event driven" thing is just a farce. You can also replicate the same thing that Node.js is doing in your Java or Python too by applying multi-threading (i.e. one thread just "waits" for the I/O in the background while the other keeps doing its job). All you've done here is just handed or delegated that complexity of multi-threading to Node.js?

Realistically, it's impossible to wait or block an I/O request while at the same time also letting the other part of the code engage in other tasks, that's the very definition of multi-threading. Doing "async" is impossible without multiple threads in that sense. Node must have a thread pool of sorts where one of them is engaged in the wait/block while another is running your JS code further. When the wait is over, the control is then passed to the "event handler" function it was bound to in that other thread.

What Node is selling as "single threaded" applies to application or business logic we are writing, node itself can't be single threaded. I feel it's better to just implement multi-threading in your own code (as needed) instead of using something convoluted and confusing like Node.js. What say you?