Hadoop Package

This page describes how to use the hadoop package in VisTrails. This package works on Mac and Linux.

Installation

Install vistrails

Get vistrails using git and check out a version supporting the hadoop package:

git clone http://vistrails.org/git/vistrails.git
cd vistrails
git checkout 976255974f2b206f030b2436a5f10286844645b0

On mac you can link this to the binary using vistrails/scripts/mac_update_bin.sh.

Install BatchQ-PBS and the RemotePBS package

This python package is used for communication over ssh. Get it with:

git clone https://github.com/rexissimus/BatchQ-PBS

Copy BatchQ-PBS/batchq to your vistrails python installations site-packages folder.

Copy BatchQ-PBS/batchq/contrib/vistrails/RemotePBS to ~/.vistrails/userpackages/

Install the hadoop package

git clone git://vgc.poly.edu:src/vistrails-hadoop.git
ln -s `pwd`/vistrails-hadoop/hadoop  ~/.vistrails/userpackages/hadoop

Modules used with the hadoop package

Dialogs.PasswordDialog

Used to specify a password to the remote machine

Remote PBS.Machine

Represents a remote machine running SSH.

• server - the server url
• username - the remote server username, default is your local username
• password - your password, connect the PasswordDialog to here
• port - the remote ssh port, set to 0 if using an ssh tunnel

Connecting to the Poly cluster through vgchead

The hadoop job submitter runs on gray02.poly.edu. If you are outside the poly network you need to use a ssh tunnel to get through the firewall.

Add this to ~/.ssh/config:

Host vgctunnel
HostName vgchead.poly.edu
LocalForward 8101 gray02.poly.edu:22

Host gray02
HostName localhost
Port 8101
ForwardX11 yes

Set up a tunnel to gray02 by running:

ssh vgctunnel

In vistrails, create a Machine module with host=gray02 and port=0. Now you have a connection that can be used by the hadoop package

HadoopStreaming

Runs a hadoop job on a remote cluster.

• CacheArchive - Jar files to upload
• CacheFiles - Other files to upload
• Combiner - combiner file to use after mapper. Can be same as reducer.
• Environment - Environment variables
• Identifier - A unique string identifying each new job. The job files on the server will be called ~/.vistrails-hadoop/.batchq.%Identifier%.*
• Input - The input file/directory to process
• Mapper - The mapper program (required)
• Output - The output directory name
• Reducer - The reducer program (optional)
• Workdir - The server workdir (Default is ~/.vistrails-hadoop)

HDFSEnsureNew

Deletes file/directory from remote HDFS storage

HDFSGet

Retrieve file/directory from remote HDFS storage. Used to get the results.

• Local File - Destination file/directory
• Remote Location - Source file/directory in HDFS storage

HDFSPut

Upload file/directory to remote HDFS storage. Used to upload mappers, reducers and data files.

• Local File - Source file/directory
• Remote Location - Destination file/directory in HDFS storage

PythonSourceToFile

PythonSource that is written to a file. Used to create mapper/reducer files.

URICreator

Creates links to locations in HDFS storage for input data and other files

Deleting a job

To make sure a job can be executed from the beginning:

• Clear the vistrails cache
• Delete the job in the job monitor by selecting it an pressing "Del"

Example

Lets try using gray02.poly.edu to run basic example with a mapper that returns info about the machine it was executed on.

You will need an account on vgchead. In a terminal run:

ssh vgctunnel

Enter your password and keep the window open. Open vistrails-hadoop/example_nodeinfo.vt. It contains a working hadoop workflow.

Enter the machine info by going to Preferences->Module Packages, select RemoteQ and click "configure...". Enter this in the configuration:

server	gray02
username	<yourusername>
port	0
password	True
defaultFS	hdfs://gray02.poly.edu:8020/user/<yourusername>/
uris	hdfs:///user/tommy/wikitext-big-notitle.csv#wikitext-big-notitle.csv

Execute the workflow. The workflow will halt while waiting for the job to finish. Pressing cancel will detach the running job an add it to the Job Monitor. The status of the execution can be checked by right-clicking HadoopStreaming and (for hadoop) selecting "View Standard error". The job can be resumed by re-executing the workflow in vistrails. Once it completes the spreadsheet will list info about the 20 lines processed by the mapper. (usually the same)

Using Amazon AWS

First do the AWS_Setup.

AWS uses "*.pem" key files for access. Make sure you have one, then edit ~/.ssh/config and add

Host aws
HostName ec2-54-201-233-14.us-west-2.compute.amazonaws.com
IdentityFile ~/.ssh/<yourusername>.pem 

after replacing the host name and path to your key file. Enter the machine info by going to Preferences->Module Packages, select RemoteQ, click "configure...", and enter this in the configuration:

server	aws
username	hadoop
port	0
password	False
defaultFS	s3n://<yourusername>/
uris	s3://cs9223/wikitext-big-notitle.csv#wikitext-big-notitle.csv

Change defaultFS to your s3 bucket

An example file is available at vistrails-hadoop/aws.vt. It contains a working hadoop workflow. Change the S3 bucket instances to point to your bucket and execute. When it finishes you should see the same result as in the Example above.