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 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
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
  1. DZone
  2. Data Engineering
  3. Databases
  4. The Redux of the Fallacies of Distributed Computing

The Redux of the Fallacies of Distributed Computing

Understand the fallacies of distributed computing — the network is reliable and latency is zero — in order to avoid them.

Oren Eini user avatar by
Oren Eini
·
Sep. 29, 18 · Opinion
Like (3)
Save
Tweet
Share
4.03K Views

Join the DZone community and get the full member experience.

Join For Free

The fallacies of distributed computing are a topic that is very near and dear to my heart. These are a set of assertions describing false assumptions that distributed applications invariably make.

The first two are:

  • The network is reliable.
  • Latency is zero.

Whenever I talk about distributed computing, the fallacies come up. And they trip people up, over and over and over again. Even people who should know better.

Which is why I read this post with horror, mostly for the following quote:

"As networks become more redundant, partitions become an increasingly rare event. And even if there is a partition, it is still possible for the majority partition to be available. Only the minority partition must become unavailable. Therefore, for the reduction in availability to be perceived, there must be both a network partition, and also clients that are able to communicate with the nodes in the minority partition (and not the majority partition)."

Now, to be clear, Daniel literally has a Ph.D. in CS and has published several papers on the topic. It is possible that he is speaking in very precise terms that don’t necessarily match the way I read this statement. But even so, I believe that this statement is absolutely and horribly wrong.

A network partition is rare, you say? This reading from 2014 paper for ACM Queue shows that this is anything but. Oh, sure, in the grand scheme of things, a network partition is an extremely rare event in a properly maintained data center, let’s say that this is a 1 / 500,000 chance for that happening (rough numbers from the Google Chubby paper). That still gives you 61 outages (!) in a few weeks.

Go and read the ACM paper, it makes for fascinating reading, in the same way, you can’t look away from a horror movie however much you want to.

And this is talking just about network partitions. The problem is that from the perspective of the individual nodes, that is not nearly the only reason why you might get a partition:

  • If running a server using a managed platform, you might hit a stop the world GC collection event. In some cases, this can be minutes.
  • In an unmanaged language, your malloc() may be doing maintenance tasks and causing an unexpected block in a bad location.
  • You may be swapping to disk.
  • The OS might have decided to randomly kill your process (Linux OOM killer).
  • Your workload has hit some critical point (see the Expires section) and cause the server to wait a long time before it can reply.
  • Your server is on a VM that was moved between physical machines.
  • A certificate expired on one machine, but not on others, meaning that it can contact others, but cannot be contacted directly (except that already existing connections still work).

All of these are before we consider the fact that we are dealing with imperfect software and that there may be bugs, that humans are tinkering with the system (such as deploying a new version) and mess things up, etc.

So no, I utterly reject the idea that partitions are rare events in any meaningful manner. Sure, they are rare, but a million to one event? We can do million packets per second. That means that something that is incredibly rare can still happen multiple times a day. In practice, you need to be aware that your software will be running in a partition, and that you will need a way to handle that.

And go read the fallacies again, maybe print them and stick them on a wall somewhere nearby. If you are working with a distributed system, it is important to remember these fallacies, because they will trip you up.

Distributed Computing Fallacy Partition (database)

Published at DZone with permission of Oren Eini, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Upgrade Guide To Spring Data Elasticsearch 5.0
  • Asynchronous HTTP Requests With RxJava
  • Why Open Source Is Much More Than Just a Free Tier
  • What Is Policy-as-Code? An Introduction to Open Policy Agent

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

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: