About asynchronous methods and threads

Question

What is really going on behind the scenes with asynchronous functions?

Does it open a new thread and allow the OS to start and run it?

If so, could this cause deadlocks or other thread problems?

Here is an example of an asynchronous method:

var fs = require('fs')
var file = process.argv[2]

fs.readFile(file, function (err, contents) {
  var lines = contents.toString().split('\n').length - 1
  console.log(lines)
})

Answer 1

In fs.readFile(file,callback). This is a non-blocking call that means.

• The node stores the main thread callbackin the event table and associate it with the event that will be emitted whenever the read process is executed.
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