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Tokutek White Paper: A Comparison of Log-Structured Merge (LSM) and Fractal Tree Indexing

Wed, 08/06/2014 - 16:56

What data structure does your database use? It's not something the typical database user spends much time pondering. Since data structure is destiny, what data structure your database uses is a key point to consider in your selection process.

We know CouchDB uses a modified B+ tree. We've learned a lot fascinating details over the years about the use of Log-structured merge-trees in Cassandra, HBase and LevelDB. So B+ trees and LSMs seem familiar by now.

What may not be so familiar is Tokutek's Fractal Tree Indexing technology that is supposed to be even better than B+ trees and LSMs.

As a comparison between Fractal Tree Indexing and LSMs, Bradley Kuszmaul, Chief Architect at Tokutek, has written a detailed paper, a must read for the algorithmically inclined or someone interested in database internals: A Comparison of Log-Structured Merge (LSM) and Fractal Tree Indexing.

Here's a quick intro to Fractal Tree (FT) indexes:

Categories: Architecture

Sponsored Post: Apple, Gawker, FoundationDB, Monitis, Cie Games, BattleCry, Surge, Cloudant, CopperEgg, Logentries, Couchbase, MongoDB, BlueStripe, AiScaler, Aerospike, AppDynamics, ManageEngine, Site24x7

Tue, 08/05/2014 - 16:56

Who's Hiring?
  • Apple has multiple openings. Changing the world is all in a day's work at Apple. Imagine what you could do here. 
    • Software Developer in Test. The iOS Systems team is looking for a Quality Assurance engineer. In this role you will be expected to work hand-in-hand with the software engineering team to find and diagnose software defects. The ideal candidate will also seek out ways to further automate all aspects of our existing process. This is a highly technical role and requires in-depth knowledge of both white-box and black-box testing methodologies. Please apply here
    • Senior Software Engineer -iOS Systems. Do you love building highly scalable, distributed web applications? Does the idea of a fast-paced environment make your heart leap? Do you want your technical abilities to be challenged every day, and for your work to make a difference in the lives of millions of people? If so, the iOS Systems Carrier Services team is looking for a talented software engineer who is not afraid to share knowledge, think outside the box, and question assumptions. Please apply here.
    • Software Engineering Manager, IS&T WWDR Dev Systems. The WWDR development team is seeking a hands-on engineering manager with a passion for building large-scale, high-performance applications. The successful candidate will be collaborating with Worldwide Developer Relations (WWDR) and various engineering teams throughout Apple. You will lead a team of talented engineers to define and build large-scale web services and applications. Please apply here.
    • C++ Senior Developer and Architect- Maps. The Maps Team is looking for a senior developer and architect to support and grow some of the core backend services that support Apple Map's Front End Services. Ideal candidate would have experience with system architecture, as well as the design, implementation, and testing of individual components but also be comfortable with multiple scripting languages. Please apply here.

  • Systems & Networking Lead at Gawker. We are looking for someone to take the initiative on the lowest layers of the Kinja platform. All the way down to power and up through hardware, networking, load-balancing, provisioning and base-configuration. The goal for this quarter is a roughly 30% capacity expansion, and the goal for next quarter will be a rolling CentOS7 upgrade as well as to planning/quoting/pitching our 2015 footprint and budget. For the full job spec and to apply, click here: http://grnh.se/t8rfbw

  • Cie Games, small indie developer and publisher in LA, is looking for rock star Senior Game Java programmers to join our team! We need devs with extensive experience building scalable server-side code for games or commercial-quality applications that are rich in functionality. We offer competitive comp, great benefits, interesting projects, and exceptional growth opportunities. Check us out at http://www.ciegames.com/careers.

  • BattleCry, the newest ZeniMax studio in Austin, is seeking a qualified Front End Web Engineer to help create and maintain our web presence for AAA online games. This includes the game accounts web site, enhancing the studio website, our web and mobile- based storefront, and front end for support tools. http://jobs.zenimax.com/requisitions/view/540

  • FoundationDB is seeking outstanding developers to join our growing team and help us build the next generation of transactional database technology. You will work with a team of exceptional engineers with backgrounds from top CS programs and successful startups. We don’t just write software. We build our own simulations, test tools, and even languages to write better software. We are well-funded, offer competitive salaries and option grants. Interested? You can learn more here.

  • UI EngineerAppDynamics, founded in 2008 and lead by proven innovators, is looking for a passionate UI Engineer to design, architect, and develop our their user interface using the latest web and mobile technologies. Make the impossible possible and the hard easy. Apply here.

  • Software Engineer - Infrastructure & Big DataAppDynamics, leader in next generation solutions for managing modern, distributed, and extremely complex applications residing in both the cloud and the data center, is looking for a Software Engineers (All-Levels) to design and develop scalable software written in Java and MySQL for backend component of software that manages application architectures. Apply here.
Fun and Informative Events
  • OmniTI has a reputation for scalable web applications and architectures, but we still lean on our friends and peers to see how things can be done better. Surge started as the brainchild of our employees wanting to bring the best and brightest in Web Operations to our own backyard. Now in its fifth year, Surge has become the conference on scalability and performance. Early Bird rate in effect until 7/24!
Cool Products and Services
  • Couchbase, MongoDB and DataStax: Compared. Find out which database delivers great read/write latency while scaling well with both read-intensive and balanced workloads. Get the initial results here: http://info.couchbase.com/2014-Benchmark-Showdown-Results-LP.html.

  • Now track your log activities with Log Monitor and be on the safe side! Monitor any type of log file and proactively define potential issues that could hurt your business' performance. Detect your log changes for: Error messages, Server connection failures, DNS errors, Potential malicious activity, and much more. Improve your systems and behaviour with Log Monitor.

  • The NoSQL "Family Tree" from Cloudant explains the NoSQL product landscape using an infographic. The highlights: NoSQL arose from "Big Data" (before it was called "Big Data"); NoSQL is not "One Size Fits All"; Vendor-driven versus Community-driven NoSQL.  Create a free Cloudant account and start the NoSQL goodness

  • Finally, log management and analytics can be easy, accessible across your team, and provide deep insights into data that matters across the business - from development, to operations, to business analytics. Create your free Logentries account here.

  • CopperEgg. Simple, Affordable Cloud Monitoring. CopperEgg gives you instant visibility into all of your cloud-hosted servers and applications. Cloud monitoring has never been so easy: lightweight, elastic monitoring; root cause analysis; data visualization; smart alerts. Get Started Now.

  • Whitepaper Clarifies ACID Support in Aerospike. In our latest whitepaper, author and Aerospike VP of Engineering & Operations, Srini Srinivasan, defines ACID support in Aerospike, and explains how Aerospike maintains high consistency by using techniques to reduce the possibility of partitions.  Read the whitepaper: http://www.aerospike.com/docs/architecture/assets/AerospikeACIDSupport.pdf.

  • BlueStripe FactFinder Express is the ultimate tool for server monitoring and solving performance problems. Monitor URL response times and see if the problem is the application, a back-end call, a disk, or OS resources.

  • aiScaler, aiProtect, aiMobile Application Delivery Controller with integrated Dynamic Site Acceleration, Denial of Service Protection and Mobile Content Management. Cloud deployable. Free instant trial, no sign-up required.  http://aiscaler.com/

  • ManageEngine Applications Manager : Monitor physical, virtual and Cloud Applications.

  • www.site24x7.com : Monitor End User Experience from a global monitoring network.

If any of these items interest you there's a full description of each sponsor below. Please click to read more...

Categories: Architecture

Tumblr: Hashing Your Way to Handling 23,000 Blog Requests per Second

Mon, 08/04/2014 - 16:56

This is a guest post by Michael Schenck, SRE Staff Engineer at Tumblr.

At Tumblr, blogs (or Tumblelog) are one of our most highly trafficked faces on the internet.  One of the most convenient aspects of tumblelogs is their highly cacheable nature, which is fantastic because of the high views/post ratio the Tumblr network offers our users.  That said, it's not entirely trivial to scale out the perimeter proxy tier, let alone the caching tier, necessary for serving all of those requests.

This article describes the architecture of the portion of our perimeter responsible for blogs serving, one of our more highly trafficked perimeter end-points.

Here's how we do it.

Stats
Categories: Architecture

Stuff The Internet Says On Scalability For August 1st, 2014

Fri, 08/01/2014 - 17:05

Hey, it's HighScalability time:


From Systems Performance: Enterprise and the Cloud.
  • Quotable Quotes:
    • @shanselman: Wife: "How was your day?" Me: "I'm using Grunt to automate NuGet creation for AngularJS." Wife: "But will that scale?" Me: "Well played."
    • John Hagel: winners in the concentrating parts of the economy are increasingly determined by the ability to connect with, and build strong relationships with, the participants who are operating in fragmenting parts of the economy.
    • Jack Clark: This means that although Amazon still grew at a respectable rate, its actual revenues were clipped by the heightened competition. This is what happens when you sell goods with deflationary pricing, it seems.

  • Taxi app Hailo on Scaling micro-services Architecture on AWS: Micro-services + Containers + Scheduling on AWS will be a dominant architecture pattern in the next few years.

  • Netflix. Revisiting 1 Million Writes per second. How will Cassandra perform on AWS's new instance types? There's no big reveal so you'll have to decide for yourself. Good discussion on reddit and Hacker News.

  • TrueTime in Google's Spanner was one of its most buzzworthy innovations. Who doesn't like atomic clocks as a way to time-stamp transactions anywhere in the world? What if you don't have spare atomic clocks? Hybrid Logical Clocks: HLC captures the causality relationship like LC, and enables easy identification of consistent snapshots in distributed systems. Dually, HLC can be used in lieu of PT clocks since it maintains its logical clock to be always close to the PT clock.

  • Vertical integration for the win. Apple is building out their own CDN with many terabits of capacity. Capable of handling traffic bursts from software downloads. Or maybe something else? More from Dan Rayburn in Apple’s CDN Now Live: Has Paid Deals With ISPs, Massive Capacity In Place

  • Clouds make a lot of money on their network pricing. Chris Swan explores this marketing magic in Cloud Price Wars – What about the network?: there haven’t been any major shifts in network pricing.

  • Scaling with Microservices and Vertical Decomposition: The architecture of otto.de is based on the concept of vertical decomposition: the whole system is vertically split into several loosely coupled applications. Every “vertical” is responsible for a single business domain such as “Order”, “Search & Navigation”, “Product”, etc. It has its own presentation layer, persistence layer and a separate database. From the development perspective, every vertical is implemented by exactly one team and no code is shared between the different systems.

Don't miss all that the Internet has to say on Scalability, click below and become eventually consistent with all scalability knowledge (which means this post has many more items to read so please keep on reading)...

Categories: Architecture

Paper: ZooKeeper: Wait-free coordination for Internet-scale systems

Thu, 07/31/2014 - 16:56

Do you really need to roll your own? ZooKeeper: Wait-free coordination for Internet-scale systems: In this paper, we describe ZooKeeper, a service for coordinating processes of distributed applications. Since ZooKeeper is part of critical infrastructure, ZooKeeper aims to provide a simple and high performance kernel for building more complex coordination primitives at the client. It incorporates elements from group messaging, shared registers, and distributed lock services in a replicated, centralized service. The interface exposed by Zoo-Keeper has the wait-free aspects of shared registers with an event-driven mechanism similar to cache invalidations of distributed file systems to provide a simple, yet powerful coordination service.

 

The ZooKeeper interface enables a high-performance service implementation. In addition to the wait-free property, ZooKeeper provides a per client guarantee of FIFO execution of requests and linearizability for all requests that change the ZooKeeper state. These design decisions enable the implementation of a high performance processing pipeline with read requests being satisfied byvlocal servers. We show for the target workloads, 2:1 to 100:1 read to write ratio, that ZooKeeper can handle tens to hundreds of thousands of transactions per second. This performance allows ZooKeeper to be used extensively by client applications.

ZooKeeper achieves throughput values of hundreds of thousands of operations per second for read-dominant workloads by using fast reads with watches, both of which served by local replicas. Although our consistency guarantees for reads and watches appear to be weak, we have shown with our use cases that this combination allows us to implement efficient and sophisticated coordination protocols at the client even though reads are not precedence-ordered and the implementation of data objects is wait-free. The wait-free property has proved to be essential for high performance.

Although we have described only a few applications, there are many others using ZooKeeper. We believe such a success is due to its simple interface and the powerful abstractions that one can implement through this interface. Further, because of the high-throughput of ZooKeeper, applications can make extensive use of it, not only course-grained locking.

Related Articles
Categories: Architecture

Preventing the Dogpile Effect - Problem and Solution

Wed, 07/30/2014 - 16:56

This is a guest repost Przemek Sobstel, who believes that dogpile effect issue is not covered enough, especially in the PHP world. Orignal article: Preventing dogpile effect.

The Dogpile effect occurs when cache expires and websites are hit by numerous requests the same time. From my own experiences working on big-traffic websites this is what I consider best the best solution. It was used sucessfully in the wild and it worked. Many people mention storing two redundant values FRESH + STALE, but for big traffic websites it was killing our network. We thought it worth sharing our solution and starting a discussion for sharing experiences.

Preventing Dogpiles
Categories: Architecture

The Great Microservices vs Monolithic Apps Twitter Melee

Mon, 07/28/2014 - 16:56

Once upon a time a great Twitter melee was fought for the coveted title of Consensus Best Way to Structure Systems. The competition was between Microservices and Monolithic Apps. 

Flying the the logo of Microservices, from a distant cloud covered land, is the Kingdom of Netflix, whose champion was Sir Adrian Cockcroft (who has pledged fealty to another). And for the Kingdom of ThoughtWorks we have Sir Sam Newman as champion.

Flying the logo of the Monolithic App is champion Sir John Allspaw, from the fair Kingdom of Etsy.

Knights from the Kingdom of Digital Ocean and several independent realms filled out the list.

To the winner goes a great prize: developer mindshare and the favor of that most fickle of ladies, Lady Luck.

May the best paradigm win.

The opening blow was wielded by the highly ranked Sir Cockcroft, a veteran of many tournaments:

Categories: Architecture

Stuff The Internet Says On Scalability For July 25th, 2014

Fri, 07/25/2014 - 17:15

Hey, it's HighScalability time:


It's systems all the way down. Bugs That Call Us Home.
  • 1 million users in just 4 days: Yo;  30 billion: Pinterest Pins
  • Quotable Quotes:
    • @GlennF: Amazon still dreams it is a startup, like a dog dreaming of chasing rabbits, twitching its legs while asleep.
    • @mfdii: Nobody knows how git works. We all just type in commands like monkeys trying to write Shakespeare. #devopsdays 
    • Benedict Evans: When you pull these strands together, smartphones don't just increase the size of the internet by 2x or 3x, but more like 5x or 10x. It's not just how many devices, but how different those devices are, that has the multiplier effect.
    • @Aaronontheweb: @codinghorror I broke this rule for myself last week. Spent 3 days fixing a problem that we finally solved by a $0.06/hour AWS bill increase
    • Physicist George Ellis: Barring something very unforeseen – the possible tests of the very large and the very small are coming towards the limits of whatever will be possible.
    • The Master Switch: Once the industry had concluded that its profits could be maximized if more people listened to fewer stations, the government, acting as if the business of America were only business, did the industry’s bidding, showing only the most feeble awareness of its consequences for the American ideal of free expression.

  • Ex-Googlers try to recreate Spanner with CockroachDB (awesome name!), which is A Scalable, Geo-Replicated, Transactional Datastore. The design is here and looks good. There's an article on Wired. Good discussion on HackerNews. A globally distributed transactional database it's not, yet, but it's early days yet. After all, they can only work in the dark.

  • Useful post on Handling 1 Billion requests a week with Symfony2. Symfony2 provides good performance and a nice development environment. HAProxy distributes to application servers. Varnish in every application’s server to keep high availability – without having a single point of failure (SPOF). Redis and MySQL for storing data. MySQL is mostly used as a third-tier cache layer (Varnish > Redis > MySQL) for non-expiring resources. 

  • The truest form of the Interest Graph on the net? Details on how Pinterest scales their data infrastructure to create a personalized discovery engine. 20 terabytes of new data each day. 10 petabytes of data in S3. 100 regular Mapreduce users run over 2,000 jobs each day through Qubole. 6 standing Hadoop clusters comprised of over 3,000 nodes. 

  • Just like Captain Kirk. Shifts In Algorithm Design: Now today, in the 21st century, we have a better way to attack problems. We change the problem, often to one that is more tractable and useful. In many situations solving the exact problem is not really what a practitioner needs. If computing X exactly requires too much time, then it is useless to compute it. A perfect example is the weather: computing tomorrow’s weather in a week’s time is clearly not very useful. The brilliance of the current approach is that we can change the problem. 

  • Wet Computing Could Put a Terabyte in a Tablespoon: Researchers from the University of Michigan and New York University demonstrated how plastic nanoparticles, deposited in a liquid, can form a one-bit cluster—the essential building block for information storage. It's called "wet computing," and the technique mimics other biological processes found in nature, like DNA in living cells.

  • Daniel Eloff: The world is not just going massively multicore, it's going heterogeneous core. The one core fits all model of programming is going away. Big performance and efficiency gains can be had from splitting your application among different types of specialized processors. Programmable hardware with FPGAs seems like a natural extension of this trend.

Don't miss all that the Internet has to say on Scalability, click below and become eventually consistent with all scalability knowledge (which means this post has many more items to read so please keep on reading)...

Categories: Architecture

Sponsored Post: Apple, Asana, FoundationDB, Cie Games, BattleCry, Surge, Dreambox, Chartbeat, Monitis, Netflix, Salesforce, Cloudant, CopperEgg, Logentries, Gengo, Couchbase, MongoDB, BlueStripe, AiScaler, Aerospike, LogicMonitor, AppDynamics, ManageEngin

Tue, 07/22/2014 - 17:00

Who's Hiring?
  • Apple has multiple openings. Changing the world is all in a day's work at Apple. Imagine what you could do here. 
    • Software Developer in Test. The iOS Systems team is looking for a Quality Assurance engineer. In this role you will be expected to work hand-in-hand with the software engineering team to find and diagnose software defects. The ideal candidate will also seek out ways to further automate all aspects of our existing process. This is a highly technical role and requires in-depth knowledge of both white-box and black-box testing methodologies. Please apply here
    • Senior Software Engineer -iOS Systems. Do you love building highly scalable, distributed web applications? Does the idea of a fast-paced environment make your heart leap? Do you want your technical abilities to be challenged every day, and for your work to make a difference in the lives of millions of people? If so, the iOS Systems Carrier Services team is looking for a talented software engineer who is not afraid to share knowledge, think outside the box, and question assumptions. Please apply here.
    • Software Engineering Manager, IS&T WWDR Dev Systems. The WWDR development team is seeking a hands-on engineering manager with a passion for building large-scale, high-performance applications. The successful candidate will be collaborating with Worldwide Developer Relations (WWDR) and various engineering teams throughout Apple. You will lead a team of talented engineers to define and build large-scale web services and applications. Please apply here.
    • C++ Senior Developer and Architect- Maps. The Maps Team is looking for a senior developer and architect to support and grow some of the core backend services that support Apple Map's Front End Services. Ideal candidate would have experience with system architecture, as well as the design, implementation, and testing of individual components but also be comfortable with multiple scripting languages. Please apply here.

  • Cie Games, small indie developer and publisher in LA, is looking for rock star Senior Game Java programmers to join our team! We need devs with extensive experience building scalable server-side code for games or commercial-quality applications that are rich in functionality. We offer competitive comp, great benefits, interesting projects, and exceptional growth opportunities. Check us out at http://www.ciegames.com/careers.

  • BattleCry, the newest ZeniMax studio in Austin, is seeking a qualified Front End Web Engineer to help create and maintain our web presence for AAA online games. This includes the game accounts web site, enhancing the studio website, our web and mobile- based storefront, and front end for support tools. http://jobs.zenimax.com/requisitions/view/540

  • FoundationDB is seeking outstanding developers to join our growing team and help us build the next generation of transactional database technology. You will work with a team of exceptional engineers with backgrounds from top CS programs and successful startups. We don’t just write software. We build our own simulations, test tools, and even languages to write better software. We are well-funded, offer competitive salaries and option grants. Interested? You can learn more here.

  • Asana. As an infrastructure engineer you will be designing software to process, query, search, analyze, and store data for applications that are continually growing in scale. You will work with a world-class team of engineers on deploying and operating existing systems, and building new ones for problems that are unique to our problem space. Please apply here.

  • Operations Engineer - AWS Cloud. Want to grow and extend a cutting-edge cloud deployment? Take charge of an innovative 24x7 web service infrastructure on the AWS Cloud? Join DreamBox Learning’s creative team of engineers, designers, and educators. Help us radically change education in an environment that values collaboration, innovation, integrity and fun. Please apply here. http://www.dreambox.com/careers

  • Chartbeat measures and monetizes attention on the web. Our traffic numbers are growing, and so is our list of product and feature ideas. That means we need you, and all your unparalleled backend engineer knowledge to help up us scale, extend, and evolve our infrastructure to handle it all. If you've these chops: www.chartbeat.com/jobs/be, come join the team!

  • The Salesforce.com Core Application Performance team is seeking talented and experienced software engineers to focus on system reliability and performance, developing solutions for our multi-tenant, on-demand cloud computing system. Ideal candidate is an experienced Java developer, likes solving real-world performance and scalability challenges and building new monitoring and analysis solutions to make our site more reliable, scalable and responsive. Please apply here.

  • Sr. Software Engineer - Distributed Systems. Membership platform is at the heart of Netflix product, supporting functions like customer identity, personalized profiles, experimentation, and more. Are you someone who loves to dig into data structure optimization, parallel execution, smart throttling and graceful degradation, SYN and accept queue configuration, and the like? Is the availability vs consistency tradeoff in a distributed system too obvious to you? Do you have an opinion about asynchronous execution and distributed co-ordination? Come join us

  • Human Translation Platform Gengo Seeks Sr. DevOps Engineer. Build an infrastructure capable of handling billions of translation jobs, worked on by tens of thousands of qualified translators. If you love playing with Amazon’s AWS, understand the challenges behind release-engineering, and get a kick out of analyzing log data for performance bottlenecks, please apply here.

  • UI EngineerAppDynamics, founded in 2008 and lead by proven innovators, is looking for a passionate UI Engineer to design, architect, and develop our their user interface using the latest web and mobile technologies. Make the impossible possible and the hard easy. Apply here.

  • Software Engineer - Infrastructure & Big DataAppDynamics, leader in next generation solutions for managing modern, distributed, and extremely complex applications residing in both the cloud and the data center, is looking for a Software Engineers (All-Levels) to design and develop scalable software written in Java and MySQL for backend component of software that manages application architectures. Apply here.
Fun and Informative Events
  • OmniTI has a reputation for scalable web applications and architectures, but we still lean on our friends and peers to see how things can be done better. Surge started as the brainchild of our employees wanting to bring the best and brightest in Web Operations to our own backyard. Now in its fifth year, Surge has become the conference on scalability and performance. Early Bird rate in effect until 7/24!
Cool Products and Services
  • A third party vendor benchmarked the performance of three databases: Couchbase Server, MongoDB and DataStax Enterprise. The databases were benchmarked with two different workloads (read-intensive / balanced) via YCSB on dedicated servers. Read.

  • Now track your log activities with Log Monitor and be on the safe side! Monitor any type of log file and proactively define potential issues that could hurt your business' performance. Detect your log changes for: Error messages, Server connection failures, DNS errors, Potential malicious activity, and much more. Improve your systems and behaviour with Log Monitor.

  • The NoSQL "Family Tree" from Cloudant explains the NoSQL product landscape using an infographic. The highlights: NoSQL arose from "Big Data" (before it was called "Big Data"); NoSQL is not "One Size Fits All"; Vendor-driven versus Community-driven NoSQL.  Create a free Cloudant account and start the NoSQL goodness

  • Finally, log management and analytics can be easy, accessible across your team, and provide deep insights into data that matters across the business - from development, to operations, to business analytics. Create your free Logentries account here.

  • CopperEgg. Simple, Affordable Cloud Monitoring. CopperEgg gives you instant visibility into all of your cloud-hosted servers and applications. Cloud monitoring has never been so easy: lightweight, elastic monitoring; root cause analysis; data visualization; smart alerts. Get Started Now.

  • Whitepaper Clarifies ACID Support in Aerospike. In our latest whitepaper, author and Aerospike VP of Engineering & Operations, Srini Srinivasan, defines ACID support in Aerospike, and explains how Aerospike maintains high consistency by using techniques to reduce the possibility of partitions.  Read the whitepaper: http://www.aerospike.com/docs/architecture/assets/AerospikeACIDSupport.pdf.

  • LogicMonitor is the cloud-based IT performance monitoring solution that enables companies to easily and cost-effectively monitor their entire IT infrastructure stack – storage, servers, networks, applications, virtualization, and websites – from the cloud. No firewall changes needed - start monitoring in only 15 minutes utilizing customized dashboards, trending graphs & alerting.

  • BlueStripe FactFinder Express is the ultimate tool for server monitoring and solving performance problems. Monitor URL response times and see if the problem is the application, a back-end call, a disk, or OS resources.

  • aiScaler, aiProtect, aiMobile Application Delivery Controller with integrated Dynamic Site Acceleration, Denial of Service Protection and Mobile Content Management. Cloud deployable. Free instant trial, no sign-up required.  http://aiscaler.com/

  • ManageEngine Applications Manager : Monitor physical, virtual and Cloud Applications.

  • www.site24x7.com : Monitor End User Experience from a global monitoring network.

If any of these items interest you there's a full description of each sponsor below. Please click to read more...

Categories: Architecture

StackOverflow Update: 560M Pageviews a Month, 25 Servers, and It's All About Performance

Mon, 07/21/2014 - 17:00

The folks at Stack Overflow remain incredibly open about what they are doing and why. So it’s time for another update. What has Stack Overflow been up to?

The network of sites that make up StackExchange, which includes StackOverflow, is now ranked 54th for traffic in the world; they have 110 sites and are growing at a rate of 3 or 4 a month; 4 million users; 40 million answers; and 560 million pageviews a month.

This is with just 25 servers. For everything. That’s high availability, load balancing, caching, databases, searching, and utility functions. All with a relative handful of employees. Now that’s quality engineering.

This update is based on The architecture of StackOverflow (video) by Marco Cecconi and What it takes to run Stack Overflow (post) by Nick Craver. In addition, I’ve merged in comments from various sources. No doubt some of the details are out of date as I meant to write this article long ago, but it should still be representative. 

Stack Overflow still uses Microsoft products. Microsoft infrastructure works and is cheap enough, so there’s no compelling reason to change. Yet SO is pragmatic. They use Linux where it makes sense. There’s no purity push to make everything Linux or keep everything Microsoft. That wouldn’t be efficient. 

Stack Overflow still uses a scale-up strategy. No clouds in site. With their SQL Servers loaded with 384 GB of RAM and 2TB of SSD, AWS would cost a fortune. The cloud would also slow them down, making it harder to optimize and troubleshoot system issues. Plus, SO doesn’t need a horizontal scaling strategy. Large peak loads, where scaling out makes sense, hasn’t  been a problem because they’ve been quite successful at sizing their system correctly.

So it appears Jeff Atwood’s quote: "Hardware is Cheap, Programmers are Expensive", still seems to be living lore at the company.

Marco Ceccon in his talk says when talking about architecture you need to answer this question first: what kind of problem is being solved?

First the easy part. What does StackExchange do? It takes topics, creates communities around them, and creates awesome question and answer sites. 

The second part relates to scale. As we’ll see next StackExchange is growing quite fast and handles a lot of traffic. How does it do that? Let’s take a look and see….

Stats
Categories: Architecture

Stuff The Internet Says On Scalability For July 18th, 2014

Fri, 07/18/2014 - 17:01

Hey, it's HighScalability time:


The one is many. Lichen composed of possibly 400 distinct species.
  • Quotable Quotes:
    • The Master Switch: Selling radio sets—the old revenue model—was a good if limited business, for ultimately few households would need more than one radio every few years. But advertising revenues could expand indefinitely—or so it seemed then.
    • Larry Page: It’s pretty difficult to solve big problems in four years. I think it’s probably pretty easy to do it in 20 years. I think our whole system is setup in a way that makes it difficult for leaders of really big companies.

  • The Master Switch: The inventors we remember are significant not so much as inventors, but as founders of “disruptive” industries, ones that shake up the technological status quo. Through circumstance or luck, they are exactly at the right distance both to imagine the future and to create an independent industry to exploit it.

  • You thought you were clever and safe? Reality doesn't like that. The fallacy of distributed transactions: In other words, as far as the queue is concerned, the transaction committed, and the message is gone. As far as the database is concerned, that transaction was rolled back, and never happened. Of course, the chance that something like that can happen in one of your systems? Probably one in a million.

  • How do you make Cassandra 50% faster? You add batching of replies. You fix your thread pools. And you get rid of unecessary endcoding and decoding phases like with Thrift. Of course now the bottleneck has moved and the process starts again.

  • Everyday Algorithms: Elevator Allocation. Though I'm pretty sure my contextualized and personalized elevator scheduling goes something like: for him, slow as possible. And they and the crosswalk lights must be in cahoots, because I get the same fine service.

  • Simon Wardley: Anyhow, this is what I don't get. Micro services has become a big thing - good. So, why do we have to continuously create 'new' terms to describe what is already happening? < Why have new songs when they use all the same words? What changes is the context. A new binding requires a new word. It's like a linguistic method of versioning. 10 years ago all the words around that eras version of microservices would be different, so we need a new word now to reflect a new world.

  • Programmers really want the database to work as a queue. It just never works in the end. But if you are Antirez and are a programmer and have your own database then you can make that happen. Queues and databases

  • Another case of breaking one thing in to two parts and then arguing which part is more important. In reference to the debate over Linus' quote on data structures: "Bad programmers worry about the code. Good programmers worry about data structures and their relationships." < Good and evil. Light and dark. Mind and Body. Starsky and Hutch. They are defined in terms of each other and make no sense without each other. They are a single system. 

  • New russian 8-core CPU. It may not be the fastest CPU, but it won't break in the field and hardly ever jams when covered in mud or sand.

Don't miss all that the Internet has to say on Scalability, click below and become eventually consistent with all scalability knowledge (which means this post has many more items to read so please keep on reading)...

Categories: Architecture

10 Program Busting Caching Mistakes

Wed, 07/16/2014 - 17:00

While Ten Caching Mistakes that Break your App by Omar Al Zabir is a few years old, it is still a great source of advice on using caches, especially on the differences between using a local in-memory cache and when using a distributed cache.

Here are the top 10 mistakes (summarized):
  1. Relying on a default serializer. Default serializers can use a lot of CPU, especially for complex types. Give some thought to the best serialization and deserialization method for your language and environment.
  2. Storing large objects in a single cache item. Because of serialization and deserialization costs, under concurrent load, frequent access to large object graphs can kill your server's CPU. Instead, break up the larger graph into smaller subgraphs and cache them separately. Retrieve only the smallest unit you need.
  3. Using cache to share objects between threads. Race conditions, when writes are involved, develop if parts of a program are accessing the same cached items simultaneously. Some sort of external locking mechanism is needed. 
  4. Assuming items will be in cache immediately after storing them. Never assume an item will be in a cache, even after it was just written, because a cache can flush items when memory gets tight. Code should always check for a null return value from a cache.
  5. Storing entire collection with nested objects. Storing an entire collection when you need to get a particular item results in poor performance because of the serialization overhead. Cache individual items separately so they can be retrieved separately. 
  6. Storing parent-child objects together and also separately. Sometimes an object will simultaneously be contained in two or more parent objects. To not have the same object stored in two different places in the cache store it on its own under its own key. The parent objects will then read the objects when access is needed.
  7. Caching Configuration settings. Store configuration data in a static variable that is local to your process. Accessing cached data is expensive so you want to avoid that cost when possible.
  8. Caching Live Objects that have open handle to stream, file, registry, or network. Don't cache objects the have references to resources like files, streams, memory, etc. When the cached item is removed from the cache those resources will not be deleted and system resources will leak. 
  9. Storing same item using multiple keys. It can be convenient to access an item by a key and an index number.  This can work when a cache is in-memory because the cache can contain a reference to the same object which means changes to the object will be seen through both access paths. When using a remote cache any updates won't be visible so the objects will get out of sync. 
  10. Not updating or deleting items in cache after updating or deleting them on persistent storage. Items in a remote cache are stored as a copy, so updating an object won't update the cache. The cache must specifically be updated for the changes to be seen by anyone else. With an in-memory cache changes to an object will be seen by everyone. Same for deletion. Deleting an object won't delete it from the cache. It's up to the program make sure cached items are deleted correctly.
Categories: Architecture

Bitly: Lessons Learned Building a Distributed System that Handles 6 Billion Clicks a Month

Mon, 07/14/2014 - 17:00

Have you ever wondered how bitly makes money? A URL shortener can’t be that hard to write, right? Sean O'Connor, Lead Application Developer at bitly, answers the how can bitly possibly make money question immediately in a talk he gave on bitly at the Bacon conference.

Writing a URL shortner that works is easy, says Sean, writing one that scales and is highly available, is not so easy.

Bitly doesn’t make money with a Shortening as a Service service, bitly makes money on an analytics product that mashes URL click data with with data they crawl from the web to help customers understand what people are paying attention to on the web. 

Analytics products began as a backend service that crawled web server logs. Logs contained data from annotated links along with cookie data to indicate where on a page a link was clicked, who clicked it, what the link was, etc. But the links all went back to the domain of the web site. The idea of making links go to a different domain than your own so that a 3rd party can do the analytics is a scary proposition, but it’s also kind of genius.

While this talk is not on bitly’s architecture, it is a thoughtful exploration on the nature of distributed systems and how you can solve bigger than one box problems with them.

Perhaps my favorite lesson from his talk is this one (my gloss):

SOA + queues + async messaging is really powerful. This approach isolates components, lets work happen concurrently, lets boxes fail independently, while still having components be easy to reason about.

I also really like his explanation for why event style messages are better than command style messages. I’ve never heard it put that way before.

Sean talks from a place of authentic experience. If you are trying to make a jump from a single box mindset to a multibox way of thinking, this talk is well worth watching. 

So let’s see what Sean has to say about distributed systems...

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Categories: Architecture

Stuff The Internet Says On Scalability For July 11th, 2014

Fri, 07/11/2014 - 17:01

Hey, it's HighScalability time:


Yesterday in history: Nikola Tesla's Birthday, born in 1856. The greatest geek who ever lived?
  • 10Gbps: New world record broadband speed of 10 Gbps over copper.
  • Quotable Quotes:
    • @BenedictEvans: There were 40m internet users when Netscape IPOed. The time's not far off when a startup with 40m users will be too small to get funded.
    • Scott Aaronson: In any case, the question I asked myself about CLEVER/PageRank was not the one that, maybe in retrospect, I should have asked: namely, “how can I leverage the fact that I know the importance of this idea before most people do, in order to make millions of dollars?”
    • chub79: µservices aren't technological as much as they are cultural.
    • @Elmood: I thought of a new term when talking about code: "It's made from unmaintainium."
    • @lxt: Amazing how quickly a bunch of nines go up in smoke.
    • @martinrue: Knock knock. Race condition. Who's there?

  • The Master Switch: The Rise and Fall of Information Empires by Tim Wu: History shows a typical progression of information technologies: from somebody’s hobby to somebody’s industry; from jury-rigged contraption to slick production marvel; from a freely accessible channel to one strictly controlled by a single corporation or cartel—from open to closed system. History also shows that whatever has been closed too long is ripe for ingenuity’s assault: in time a closed industry can be opened anew, giving way to all sorts of technical possibilities and expressive uses for the medium before the effort to close the system likewise begins again.

  • Tim Freeman indulges a well developed Technothantos Complex and comes up with a great big list of outage postmortems. You'll find the usual, outages from configuration issues, failover failures, quorumnesia, protocol flapping, bugs in not your stuff that causes bugs in your stuff, power outages, capacity problems, JPOBs (just plain old bugs), DDOS attacks, and good old operator error. 

  • Pinterest describes PinLater, An asynchronous job execution system. PinLater executes hundreds of different job types at a processing rate of over 100,000 per second. So you may say yet another async job system, but it's clear keeping such a critical part of their infrastructure in house makes sense. The article is a good explanation of a fairly standard approach. It used Thrift for the API, it's written in Java, Twitter’s Finagle is used for the RPC framework. MySQL is "used for relatively low throughput use cases and those that schedule jobs over long periods and thus can benefit from storing jobs on disk rather than purely in memory." Redis is "used for high throughput job queues that are normally drained in real time." Horizontal scaling is via sharding. 

  • In science class we did this one day, but I just couldn't do it. Dissecting Message Queues. Tyler Treat looks at both brokerless and brokered queues by looking a throughput benchmarks, latency benchmarks, and through qualitative analysis. No winner was declared, but if you are making a choice in this area it's well worth reading. 

  • 40 Million hits a day on WordPress using a $10 VPS. Sure, it's a static site, but still a good example of what can be done these days. Stack: Nginx + PHP-FPM (aka LEMP Stack) + Microcaching. 

Don't miss all that the Internet has to say on Scalability, click below and become eventually consistent with all scalability knowledge (which means this post has many more items to read so please keep on reading)...

Categories: Architecture