Click here to close now.

Welcome!

Microservices Journal Authors: SmartBear Blog, Elizabeth White, Liz McMillan, Louis Evans, Pat Romanski

Related Topics: SDN Journal, Java, Microservices Journal, Virtualization, Cloud Expo, Big Data Journal

SDN Journal: Blog Feed Post

Back to Basics: Least Connections Is Not Least Loaded

When load balancing, "least connections" does not mean "least loaded"

Performance is important, and that means it's important that our infrastructure support the need for speed. Load balancing algorithms are an integral piece of the performance equation and can both improve - or degrade - performance.

That's why it's important to understand more about the algorithms than their general selection mechanism. Understanding that round robin is basically an iterative choice, traversing a list one by one is good - but understanding what that means in terms of performance and capacity on different types of applications and application workloads is even better.

We last checked out "fastest response time" and today we're diving into "least connections" which, as stated above, does not mean "least loaded."

INTRA-APPLICATION WORKLOADS 

The industry standard "Least connections" load balancing algorithm uses the number of current connections to each application instance (member) to make its load balancing decision. The member with the least number of active connections is chosen. Pretty simple, right?

The premise of this algorithm is a general assumption that fewer connections (and thus fewer users) means less load and therefore better performance. That's operational axiom #2 at work - if performance decreases as load increases it stands to reason that performance increases as load decreases.

That would be true (and in the early days of load balancing it was true) if all intra-application workloads required the same resources. Unfortunately, that's no longer true and the result is uneven load distribution that leads to unpredictable performance fluctuations as demand increases.

Consider a simple example: a user logging into a system takes at least one if not more database queries to validate credentials and then update the system to indicate the activity. Depending on the nature of the application, other intra-application activities will require different quantities of resources. Some are RAM heavy, others CPU heavy, others file or database heavy. Furthermore, depending on the user in question, the usage pattern will vary greatly. One hundred users can be logged into the same system (requiring at a minimum ten connections) but if they're all relatively idle, the system will be lightly loaded and performing well.

Conversely, another application instance may boast only 50 connections, but all fifty users are heavily active with database queries returning large volumes of data. The system is far more heavily loaded and performance may be already beginning to suffer.

When the next request comes in, however, the load balancer using a "least connections" algorithm will choose the latter member, increasing the burden on that member and likely further degrading performance.

The premise of the least connections algorithm is that the application instance with the fewest number of connections is the least loaded. Except, it's not.

The only way to know which application instance is the least loaded is to monitor its system variables directly, gathering CPU utilization and memory and comparing it against known maximums. That generally requires either SNMP, agents, or other active monitoring mechanisms that can unduly tax the system in and of itself by virtue of consuming resources.

This is a quandary for operations, because "application workload" is simply too broad a generalization. Certainly some applications are more I/O heavy than others, still others are more CPU or connection heavy. But all applications have both a general workload profile and an intra-application workload profile. Understanding the usage patterns - the intra-application workload profile - of an application is critical to being able to determine how best to not only choose a load balancing algorithm but specify any limitations that may provide better overall performance and use of capacity during execution.

As always, being aware of the capabilities and the limitations of a given load balancing algorithm will assist in choosing one that is best able to meet the performance and availability requirements of an application (and thus the business).

Read the original blog entry...

More Stories By Lori MacVittie

Lori MacVittie is responsible for education and evangelism of application services available across F5’s entire product suite. Her role includes authorship of technical materials and participation in a number of community-based forums and industry standards organizations, among other efforts. MacVittie has extensive programming experience as an application architect, as well as network and systems development and administration expertise. Prior to joining F5, MacVittie was an award-winning Senior Technology Editor at Network Computing Magazine, where she conducted product research and evaluation focused on integration with application and network architectures, and authored articles on a variety of topics aimed at IT professionals. Her most recent area of focus included SOA-related products and architectures. She holds a B.S. in Information and Computing Science from the University of Wisconsin at Green Bay, and an M.S. in Computer Science from Nova Southeastern University.

@MicroservicesExpo Stories
A few weeks ago, SmartBear hosted API Craft Boston with the folks from Akana, Ian Goldsmith and Laura Heritage, to talk about microservices. It was an extremely informative presentation of where microservices came from, what it solves, and considerations around how it might fit into an organizational API strategy. It’s one thing to read everyone else’s opinions on blogs, twitter, etc. It’s great to go to workshops and conferences, but this was so intelligently presented (and for a meetup too)...
Chef and Canonical announced a partnership to integrate and distribute Chef with Ubuntu. Canonical is integrating the Chef automation platform with Canonical's Machine-As-A-Service (MAAS), enabling users to automate the provisioning, configuration and deployment of bare metal compute resources in the data center. Canonical is packaging Chef 12 server in upcoming distributions of its Ubuntu open source operating system and will provide commercial support for Chef within its user base.
While DevOps most critically and famously fosters collaboration, communication, and integration through cultural change, culture is more of an output than an input. In order to actively drive cultural evolution, organizations must make substantial organizational and process changes, and adopt new technologies, to encourage a DevOps culture. Moderated by Andi Mann, panelists will discuss how to balance these three pillars of DevOps, where to focus attention (and resources), where organizations m...
Today, the demand for new applications is growing at an unprecedented rate throughout lines of business and across industries. Customer expectations for mobile and e-commerce capabilities are transforming software development speed and quality into a competitive differentiator for even the most unlikely businesses. For existing software development shops, the proliferation of platforms, increasing need for total global uptime, and accelerating pace of industry disruption by fast-paced startups h...
of cloud, colocation, managed services and disaster recovery solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. TierPoint, LLC, is a leading national provider of information technology and data center services, including cloud, colocation, disaster recovery and managed IT services, with corporate headquarters in St. Louis, MO. TierPoint was formed through the strategic combination of some of t...
How do you securely enable access to your applications in AWS without exposing any attack surfaces? The answer is usually very complicated because application environments morph over time in response to growing requirements from your employee base, your partners and your customers. In his session at 16th Cloud Expo, Haseeb Budhani, CEO and Co-founder of Soha, will share five common approaches that DevOps teams follow to secure access to applications deployed in AWS, Azure, etc., and the frict...
SYS-CON Events announced today that Soha will exhibit at SYS-CON's DevOps Summit New York, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Soha delivers enterprise-grade application security, on any device, as agile as the cloud. This turnkey, cloud-based service enables customers to solve secure application access and delivery challenges that traditional or virtualized network solutions cannot solve because they are too expensive, inflexible and operational...
SYS-CON Events announced today that Vicom Computer Services, Inc., a provider of technology and service solutions, will exhibit at SYS-CON's 16th International Cloud Expo®, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. They are located at booth #427. Vicom Computer Services, Inc. is a progressive leader in the technology industry for over 30 years. Headquartered in the NY Metropolitan area. Vicom provides products and services based on today’s requirements...
SYS-CON Events announced today that Ciqada will exhibit at SYS-CON's @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Ciqada™ makes it easy to connect your products to the Internet. By integrating key components - hardware, servers, dashboards, and mobile apps - into an easy-to-use, configurable system, your products can quickly and securely join the internet of things. With remote monitoring, control, and alert messaging capability, you will mee...
What exactly is a cognitive application? In her session at 16th Cloud Expo, Ashley Hathaway, Product Manager at IBM Watson, will look at the services being offered by the IBM Watson Developer Cloud and what that means for developers and Big Data. She'll explore how IBM Watson and its partnerships will continue to grow and help define what it means to be a cognitive service, as well as take a look at the offerings on Bluemix. She will also check out how Watson and the Alchemy API team up to off...
Thought experiment: let’s say your app gets a message from somewhere, perhaps from another app, but you don’t know from where. The message contains the number 47 but no other information. What should your app do with the message? The answer: nothing. There’s no way for your app to make any sense out of a single datum with no context, no additional information or metadata about the datum itself. Now, let’s scale up this thought experiment to a data lake. There are a few common definitions o...
The 17th International Cloud Expo has announced that its Call for Papers is open. 17th International Cloud Expo, to be held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, APM, APIs, Microservices, Security, Big Data, Internet of Things, DevOps and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding bu...
Change becomes the central principle of today’s enterprises, and thus business agility becomes the most important characteristic our organizations must exhibit. Agile Architecture lays out a best practice approach for achieving this agility – and thus drives and coordinates the other revolutions, as both digital and DevOps are about being able to deal with change better as well.
The concept and subsequent adoption of 'Containerization'' is growing at a rapid speed with the support of almost every other major player in the industry. This concept is much more efficient than the Virtualization which has been a major option for Infrastructure optimization in the past decade. The following factors distinguish a Container from a Virtual Machine. Containers contain Only the Application Specific libraries and binaries. They do not include a guest operating system. Rather ...
There's a real buzz about microservices and containers in the application development and DevOps communities, and of course these are topics we've been talking about a great deal lately here at XebiaLabs too. Microservices and containers offer many attractive features, not least the potential for enhanced flexibility, and a robust architecture based on best-fit services. What we at XebiaLabs are really interested in is how organizations can effectively deliver microservices-based apps to bett...
SYS-CON Events announced today that Column Technologies, a global technology solutions company, will exhibit at SYS-CON's DevOps Summit 2015 New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Established in 1998, Column Technologies is a leader in application performance and infrastructure management for commercial and federal markets. The company is headquartered in the United States, with a diverse and talented team of more than 350 employees around th...
Financial services organizations were among the earliest enterprise adopters of cloud computing. The ability to leverage massive compute, storage and networking resources via RESTful APIs and automated tools like Chef and Puppet made it possible for their high-horsepower IT users to develop a whole new array of applications. Companies like Wells Fargo, Fidelity and BBVA are visible, vocal and engaged supporters of the OpenStack community, running production clouds for applications ranging from d...
As we recently previewed (read more about our London PoP in Jesse's post), Blue Box is opening a new Data Center in London, but hadn't announced the provider. Today we're excited to partner with TelecityGroup, whom we've selected as our data center partner in London. We chose their Powergate location, which is one of the U.K.'s most advanced, flexible and energy efficient carrier-neutral data centres. Why does that matter to you? Well, when customers choose Blue Box, they're trusting us with ...
Cloud Expo New York is happening from June 9 - 11. This event brings together the worlds of Cloud Computing, DevOps, IoT, WebRTC, Big Data and SDDC. We hope to see you there-members of the Blue Box team will exhibit in booth 218 next to the DevOps area. Plus, our Chief Product Officer, Hernan Alvarez, will present his talk "The Cloud Has a Down-and-Dirty Lining" as part of the Operations track in the DevOps Summit portion of the event on June 9 at 11 am. Learn more about his session her...
The 5th International DevOps Summit, co-located with 17th International Cloud Expo – being held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the...