Welcome!

Industrial IoT Authors: Pat Romanski, William Schmarzo, Elizabeth White, Stackify Blog, Yeshim Deniz

Related Topics: Java IoT, Industrial IoT, Microsoft Cloud, Open Source Cloud, Machine Learning , Apache

Java IoT: Article

Caching: Up and Down the Stack

Boston Web Performance Meetup Wrap-up

The other month I presented Caching Up and Down the Stack at the Boston Web Performance meetup. It was great to get the chance to present to the 60+ people who came out for the talk. Unsurprisingly, many of the people there knew a lot about caching in all of the different levels I touched on, and some great conversation developed.

I covered six of the major areas of caching available to web devs today. On the HTML / JS / CSS side, you can use client asset caches, full-page HTTP caches (like Varnish) and partial template caches. On the back end, you can use generated code caches, manually cache objects in memory or nearby services or even enable your database’s query cache (though, as the audience reminded me, if you’re using MySQL, just don’t. See below for why). Caching at each layer has advantages and disadvantages, and throughout, you’ll only be effective if you know what you’re caching, why you’re caching it and if you measure the improvement of doing so. If you want to know more, check out the slides on Slideshare.

Obviously, this is a huge topic, and I didn’t come anywhere close to doing it justice. The audience came up with several interesting points, both during and afterwards.

1. One of the first questions I got was about a comparison between a cached an uncached page load. I showed this graph:

The main takeaway from this is the drop in bandwidth. 500k isn’t a trivial amount to download, especially when spread over 20-odd files, and doubly so when on a mobile browser. That’s a great improvement when cached, but somebody asked, “Why did the number of requests change?” It turns out that specifying a file as cacheable doesn’t necessarily imply that a connection to the server is unnecessary. For instance, files with an etag header set will validate against the server, and the server will return a 304 Unmodified if the etag matches. On the other hand, if the Cache-Control header is set with “public” and an appropriate max-age directive, the content doesn’t have to be validated, and the browser may entirely eliminate the HTTP request.These days, this can actually be quite effective, as the ratio of time spent downloading content vs. establishing connections is lower than it has ever been. If you’ve got content that doesn’t change (because it’s versioned in the filename, for instance), set it as Cache-Control: public, max-age=large-number!

2. In the words of one wise audience member, “The MySQL query cache sucks. Never use it.” I don’t disagree. But why? Consider the following properties of this cache:

  • It only caches exact matches on queries.
  • It is invalidated every time anything in the table changes.

If you think about your data and access patterns, there’s a good chance one or both of these properties make the MySQL query cache unsuitable for production use. Few apps have large, static data sets and unpredictable but highly repetitive queries. In most cases, the query cache will spend its time in two states – cold and empty, or flushing itself. Neither will make your application appreciably faster.

Instead, consider caching objects at a coarser granularity once you’ve retrieved them from the DB, or consider adding a proper set of indices to ensure that common queries to your tables are quick.

3. Though I spent most of my time on object caching, I neglected to mention one of the most effective places to cache language objects: in memory on the machine it’s used on! Object caching is generally any type of caching that’s done by retrieving an object from a slower data store (that may involve an expensive computation), and storing the result in an easy-to-lookup place. While memcache in great for this, and has the advantage of scaling independently of your app itself, sometimes just stashing an object in a global dictionary can be the best solution. Plus, especially if the set is bounded or never changes, invalidation and cleanup can be as easy as waiting until your next deploy to reboot the app servers!

All in all, it was great to see everybody out, and I’m looking forward to the next Boston Web Performance Meet-up!

Related Articles

The 5 Critical Things You Need to Know to Assure Optimal Performance in the Cloud

QoS, Wherefore Art Thou

Solving Slow Database Performance In Java and MySQL

More Stories By TR Jordan

A veteran of MIT’s Lincoln Labs, TR is a reformed physicist and full-stack hacker – for some limited definition of full stack. After a few years as Software Development Lead with Thermopylae Science and Techology, he left to join Tracelytics as its first engineer. Following Tracelytics merger with AppNeta, TR was tapped to run all of its developer and market evangelism efforts. TR still harbors a not-so-secret love for Matlab-esque graphs and half-baked statistics, as well as elegant and highly-performant code. Read more of his articles at www.appneta.com/blog or visit www.appneta.com.

IoT & Smart Cities Stories
While the focus and objectives of IoT initiatives are many and diverse, they all share a few common attributes, and one of those is the network. Commonly, that network includes the Internet, over which there isn't any real control for performance and availability. Or is there? The current state of the art for Big Data analytics, as applied to network telemetry, offers new opportunities for improving and assuring operational integrity. In his session at @ThingsExpo, Jim Frey, Vice President of S...
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, provided an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settl...
@CloudEXPO and @ExpoDX, two of the most influential technology events in the world, have hosted hundreds of sponsors and exhibitors since our launch 10 years ago. @CloudEXPO and @ExpoDX New York and Silicon Valley provide a full year of face-to-face marketing opportunities for your company. Each sponsorship and exhibit package comes with pre and post-show marketing programs. By sponsoring and exhibiting in New York and Silicon Valley, you reach a full complement of decision makers and buyers in ...
Two weeks ago (November 3-5), I attended the Cloud Expo Silicon Valley as a speaker, where I presented on the security and privacy due diligence requirements for cloud solutions. Cloud security is a topical issue for every CIO, CISO, and technology buyer. Decision-makers are always looking for insights on how to mitigate the security risks of implementing and using cloud solutions. Based on the presentation topics covered at the conference, as well as the general discussions heard between sessio...
The Internet of Things is clearly many things: data collection and analytics, wearables, Smart Grids and Smart Cities, the Industrial Internet, and more. Cool platforms like Arduino, Raspberry Pi, Intel's Galileo and Edison, and a diverse world of sensors are making the IoT a great toy box for developers in all these areas. In this Power Panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists discussed what things are the most important, which will have the most profound e...
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, compared the Jevons Paradox to modern-day enterprise IT, examin...
Rodrigo Coutinho is part of OutSystems' founders' team and currently the Head of Product Design. He provides a cross-functional role where he supports Product Management in defining the positioning and direction of the Agile Platform, while at the same time promoting model-based development and new techniques to deliver applications in the cloud.
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
LogRocket helps product teams develop better experiences for users by recording videos of user sessions with logs and network data. It identifies UX problems and reveals the root cause of every bug. LogRocket presents impactful errors on a website, and how to reproduce it. With LogRocket, users can replay problems.
Data Theorem is a leading provider of modern application security. Its core mission is to analyze and secure any modern application anytime, anywhere. The Data Theorem Analyzer Engine continuously scans APIs and mobile applications in search of security flaws and data privacy gaps. Data Theorem products help organizations build safer applications that maximize data security and brand protection. The company has detected more than 300 million application eavesdropping incidents and currently secu...