Assignments
Data-Intensive Distributed Computing (Winter 2024)

Assignment 0: Warmup due 4:00 pm, Jan. 24

The purpose of this assignment is to serve as a warmup exercise and a practice "dry run" for the submission procedures of subsequent assignments. You'll have to write a bit of code but this assignment is mostly about the "mechanics" of setting up your Hadoop development environment. In addition to running single-node Hadoop (also known as "local mode"), either on the Linux student CS environment or on your own machine, you'll also try running jobs on the Datasci cluster.

The general setup is as follows: you will complete your assignments and check everything into a private Git repo. Shortly after the assignment deadline, we'll pull your repo for marking.

Setting up Hadoop and Spark

Hadoop and Spark are already installed in the linux.student.cs.uwaterloo.ca environment (you just need to do some simple config). Alternatively, you may wish to install everything locally on your own machine. For both, see the software page for more details.

Bespin is a library that contains reference implementations of "big data" algorithms in MapReduce and Spark. We'll be using it throughout this course. Go and run the Word Count in MapReduce and Spark example as shown in the Bespin README (clone and build the repo, download the data files, run word count in both MapReduce in Spark, and verify output). Assuming you are using linux.student.cs.uwaterloo.ca (or if you have properly set up your local environment), this task should be as simple as copying and pasting commands from the Bespin README.

Time to write some code!

Create a private repo called bigdata2024w on UW GitLab. If you're not already familiar with Git, there are plenty of good tutorials online: do a simple web search and find one you like.

What you're going to do now is to copy the MapReduce word count example into you own private repo. Start with this pom.xml: copy it into your bigdata2024w repo.

Next, copy:

• bespin/src/main/java/io/bespin/java/mapreduce/wordcount/WordCountSimple.java over to
• bigdata2024w/src/main/java/ca/uwaterloo/cs451/a0/WordCountSimple.java.

Tip: mkdir -p creates parent directories as needed.

Open up this new version of WordCountSimple.java using a text editor (or your IDE of choice) and change the Java package to ca.uwaterloo.cs451.a0.

Now, in the bigdata2024w/ base directory, you should be able to run Maven to build your package:

$ mvn clean package

Once the build succeeds, you should be able to run the word count demo program in your own repository:

$ hadoop jar target/assignments-1.0.jar ca.uwaterloo.cs451.a0.WordCountSimple \
   -input data/Shakespeare.txt -output wc

You should be running this in the Linux student CS environment or on your own machine. Note that you'll need to copy over the Shakespeare collection in data/. The output should be exactly the same as the same program in Bespin, but the difference here is that the code is now in a repository under your control.

Let's make a simple modification to word count: I would like to know the distribution (counts) of all words that follow the word "perfect". That is, for the phrase "perfect x", I want to know how many times each word appears as the x, where x is any non-zero-length word. To reduce noise, I am not interested in x's that appear only once.

Important: To be clear, use the "words" as generated by the class io.bespin.java.util.Tokenizer class in Bespin. This will ensure consistent handling of corner cases involving empty strings, words containing punctuation, etc.

A Simple Modification to Word Count

Create a program called PerfectX in the package ca.uwaterloo.cs451.a0 that implements the specifications above.

$ hadoop jar target/assignments-1.0.jar ca.uwaterloo.cs451.a0.PerfectX \
   -input data/Shakespeare.txt -output cs451-bigdatateach-a0-shakespeare

You shouldn't need to write more than a couple lines of code (beyond changing class names and other boilerplate). We'll go over the Hadoop API in more detail in class, but the changes should be straightforward.

Answer the following questions:

Question 1. In the Shakespeare collection, what is the most frequent x and how many times does it appear? (Answer this question with command-line tools.)

You can run the above instructions using check_assignment0_public_linux.py as follows:

$ wget https://www.student.cs.uwaterloo.ca/~cs451/assignments/check_assignment0_public_linux.py 
$ chmod +x check_assignment0_public_linux.py
$ ./check_assignment0_public_linux.py bigdatateach

We'll be using exactly this script to check your assignment in the Linux Student CS environment (obviously, with your username instead of bigdatateach). Important: Make sure that your code runs there even if you do development on your own machine.

Using the Datasci Cluster

The software page has details on getting started with the Datasci cluster. Make sure you've properly set up the proxy to view the cluster Resource Manager (RM) webapp. Getting access to the RM webapp is important—you'll need it to track your job status and for debugging purposes.

Once you've ssh'ed into the Datasci cluster, you should be able to run your copy of the word count program (copied over from Bespin) from your assignments repo bigdata2024w/:

$ hadoop jar target/assignments-1.0.jar ca.uwaterloo.cs451.a0.WordCountSimple \
   -input /data/cs451/enwiki-20180901-sentences-0.1sample.txt -output wc-wiki

Note that we're running word count over a larger collection here: a 10% sample of English Wikipedia totaling 1.87 GB (here's a chance to exercise your newly-acquired HDFS skills to confirm for yourself).

Question 2. Run word count on the Datasci cluster and make sure you can access the Resource Manager webapp. What is your application id? It looks something like application_XXXXXXXXXXXXX_XXXX and can be found in the Resource Manager webapp. If you ran word count multiple times, any id will do.

Question 3. For this word count job, how many mappers ran in parallel?

Question 4. From the word count program, how many times does "waterloo" appear in the sample Wikipedia collection?

Now run your PerfectX program on the sample Wikipedia data:

$ hadoop jar target/assignments-1.0.jar ca.uwaterloo.cs451.a0.PerfectX \
   -input /data/cs451/enwiki-20180901-sentences-0.1sample.txt -output cs451-bigdatateach-a0-wiki

Question 5. In the sample Wikipedia collection, what are the 10 most frequent x's and how many times does each appear? (Answer this question with command-line tools.)

Note that the Datasci cluster is a shared resource, and how fast your jobs complete will depend on how busy it is. You're advised to begin the assignment early as to avoid long job queues. "I wasn't able to complete the assignment because there were too many jobs running on the cluster" will not be accepted as an excuse if your assignment is late.

You can run the above instructions using check_assignment0_public_datasci.py as follows:

$ wget https://www.student.cs.uwaterloo.ca/~cs451/assignments/check_assignment0_public_datasci.py
$ chmod +x check_assignment0_public_datasci.py
$ ./check_assignment0_public_datasci.py bigdatateach

We'll be using exactly this script to check your assignment on the Datasci cluster (with your username instead of bigdatateach).

Turning in the Assignment

At this point, you should have a Git repo bigdata2024w/ and inside the repo, you should have the word count program copied over from Bespin, and the new perfect x count implementation, along with your pom.xml. Commit these files. Next, create a file called assignment0.md inside bigdata2024w/. In that file, put your answers to the above questions (1—5). Use the Markdown annotation format: here's a simple guide.

Note: DO NOT commit data/ or target/ (or any results that you may have generated), so your repo should be very compact — it should only have five files: two Java source files, pom.xml, and assignment0.md. You can add a .gitignore file if you wish. Make sure you do not add assignment?_marks.md to .gitignore, because it prevents us from pushing your mark report to the repository

Here's an example .gitignore file that ignores all files other than the ones you need to submit (for this and future assignments).

# Ignore everything but descend into subdirectories
*
!*/

# But not these files...
!.gitignore
!pom.xml
!src/**
!*.md
# on a later assignment you're asked to submit a chart in PDF form.
!*.pdf