DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports
Events Video Library
Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
View Events Video Library
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

Integrating PostgreSQL Databases with ANF: Join this workshop to learn how to create a PostgreSQL server using Instaclustr’s managed service

Mobile Database Essentials: Assess data needs, storage requirements, and more when leveraging databases for cloud and edge applications.

Monitoring and Observability for LLMs: Datadog and Google Cloud discuss how to achieve optimal AI model performance.

Automated Testing: The latest on architecture, TDD, and the benefits of AI and low-code tools.

Related

  • Towards a Knowledge Graph Economy. The Year of the Graph Newsletter, Summer 2020
  • Positive Impact of Graph Technology and Neural Networks on Cybersecurity
  • Getting Started With ReGraph — The Graph Visualization Toolkit for React
  • How to Leverage the MuleSoft Anypoint Visualizer

Trending

  • Understanding Git
  • Creating a Deep vs. Shallow Copy of an Object in Java
  • The Emergence of Cloud-Native Integration Patterns in Modern Enterprises
  • Application Integration for IoT Devices: A Detailed Guide To Unifying Your Ecosystem
  1. DZone
  2. Software Design and Architecture
  3. Cloud Architecture
  4. MapReduce: Detecting Cycles in a Network Graph

MapReduce: Detecting Cycles in a Network Graph

Ricky Ho user avatar by
Ricky Ho
·
Jan. 04, 13 · Interview
Like (0)
Save
Tweet
Share
6.64K Views

Join the DZone community and get the full member experience.

Join For Free

I recently received an email from an audience of my blog on Map/Reduce algorithm design regarding how to detect whether a graph is acyclic using Map/Reduce.  I think this is an interesting problem and can imagine there can be wide range of application to it.

Although I haven't solved this exact problem in the past, I'd like to sketch out my thoughts on a straightforward approach, which may not be highly optimized.  My goal is to invite other audience who has solved this problem to share their tricks.

To define the problem:  Given a simple directed graph, we want to tell whether it contains any cycles.

Lets say the graph is represented in incidence edge format where each line represent an edge from one node to another node.  The graph can be split into multiple files.

node1, node2
node4, node7
node7, node1
....

Here is a general description of the algorithm.

We'll maintain two types of graph data.

  1. A set of link files where each line represent an edge in the graph.  This file will be static.
  2. A set of path files where each line represent a path from one node to another node.  This file will be updated in each round of map/reduce.
The general idea is to grow the path file until either the path cannot grow further, or the path contain a cycle, we'll use two global flags to keep track of that: "change" flag to keep track of whether new path is discovered, and "cycle" flag to keep track whether a cycle is detected.

The main driver program will create the initial path file by copying the link file.  And it will set the initial flag condition:  Set cycle and change flag to true.  In each round, the driver will
  • Check if the cycle is still false and change is true, exit if this is not the case
  • Otherwise, it will clear the change flag and invoke the map/reduce
Within each round, the map function will do the following
  • Emit the tuple [key=toNode, value=fromNode] if it is a path
  • Emit the tuple [key=fromNode, value=toNode] if it is a link
This ensure a path and all extended link reaches the same reducer, which will do the following
  • Check to see if the beginning point of the path is the same as the endpoint of the link.  If so, it detects a cycle and mark the cycle flag to be true.
  • Otherwise, it compute the product of every path to every link, and form the new path which effectively extend the length by one.

The following diagram illustrates the algorithm ...



Graph (Unix) MapReduce Network

Published at DZone with permission of Ricky Ho, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Related

  • Towards a Knowledge Graph Economy. The Year of the Graph Newsletter, Summer 2020
  • Positive Impact of Graph Technology and Neural Networks on Cybersecurity
  • Getting Started With ReGraph — The Graph Visualization Toolkit for React
  • How to Leverage the MuleSoft Anypoint Visualizer

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 3343 Perimeter Hill Drive
  • Suite 100
  • Nashville, TN 37211
  • support@dzone.com

Let's be friends: