Asynchronous Experiment

Project Directory

Create a new project directory named "sync-async".

The remainder of our work will be in this directory.

/sync-async

names1.txt

Create a text file named "names1.txt".

Put any names/content you like into the file and save.

Asha
Wilma
Zandra

names2.txt

Create a text file named "names2.txt".

Put any names/content you like into the file and save.

Bob
Kofi
Mark

Report File

Create a new report text file named "sync-async.txt". Enter the two labels as shown.

file: sync-async.txt

** Synchronous Computation **

** Asynchronous Computation **

Code for Experiment

Save this Node.js source into a file named "sync.js".

This code reads two files and logs (prints to console) status messages.

const
	fs = require('fs'),
	path1 = 'names1.txt',
	path2 = 'names2.txt',
	log = (obj) => console.log(obj.toString());

let fileContents1, fileContents2;

log('starting tasks');
log(`started reading ${path1}`);
fileContents1 = fs.readFileSync(path1);
log(`started reading ${path2}`);
fileContents2 = fs.readFileSync(path2);
log('finished tasks');

Run

Run the node file

> node sync

Observations

Observe the output.

Jot (into your report file) down a few basic observations. Do both file reads appear to run at the same time? Does the computation wait at any point?

Note: your report can be short -- a few lines.

Note that you may like to tweak the experiment, e.g., adding more log lines, etc.

log('starting tasks');
etc.

Code for Experiment

Save this Node.js source into a file named "async.js".

This time, you'll need to log (print to console) your own status messages. It may take a few runs to get them into the locations that give you the most helpful output.

hints

Add status messages in each callback function as well as in the main code
You may be able to find a strategic location to print a courtesy message like "please wait..."

const
	fs = require('fs'),
	path1 = 'names1.txt',
	path2 = 'names2.txt',
	log = (obj) => console.log(obj.toString());
	
const callbackFct1 = (err, aFileContents) => {
	if (err) throw err;
}

const callbackFct2 = (err, aFileContents) => {
	if (err) throw err;
}

fs.readFile(path1, callbackFct1);
fs.readFile(path1, callbackFct2);

Run

Run the node file

> node sync

Observations

Observe the output.

Jot (into your report file) down a few basic observations. Do both file reads appear to run at the same time? Does the computation wait at any point?

Note that you may like to tweak the experiment, e.g., adding more log lines, etc.

log('starting tasks');
etc.