Click here to close now.

Welcome!

Big Data Journal Authors: Pat Romanski, Liz McMillan, Ian Khan, Roger Strukhoff, Harry Trott

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.

@BigDataExpo Stories
SYS-CON Events announced today that AIC, a leading provider of OEM/ODM server and storage 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. AIC is a leading provider of both standard OTS, off-the-shelf, and OEM/ODM server and storage solutions. With expert in-house design capabilities, validation, manufacturing and production, AIC's broad selection of products are highly flexible and are conf...
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 Blue Box has been named “Bronze Sponsor” of SYS-CON's DevOps Summit New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Blue Box delivers Private Cloud as a Service (PCaaS) to a worldwide customer base. Built on a technology platform leveraging decades of operational expertise in cloud and distributed systems, Blue Box Cloud is a managed private cloud product available in both hosted and on-prem versions. Each Blue Box ...
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...
As cloud gives an opportunity to businesses to buy services externally – how is cloud impacting your customers? In his General Session at 15th Cloud Expo, Fabio Gori, Director of Worldwide Cloud Marketing at Cisco, provided answers to big questions: Do you see hybrid cloud as where the world is going? What benefits does it bring? And how does Cisco connect all of these clouds? He also discussed Intercloud and Cisco’s investment on it.
SYS-CON Events announced today that B2Cloud, a provider of enterprise resource planning software, 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. B2cloud develops the software you need. They have the ideal tools to help you work with your clients. B2Cloud’s main solutions include AGIS – ERP, CLOHC, AGIS – Invoice, and IZUM
There is no doubt that Big Data is here and getting bigger every day. Building a Big Data infrastructure today is no easy task. There are an enormous number of choices for database engines and technologies. To make things even more challenging, requirements are getting more sophisticated, and the standard paradigm of supporting historical analytics queries is often just one facet of what is needed. As Big Data growth continues, organizations are demanding real-time access to data, allowing immed...
The world's leading Cloud event, Cloud Expo has launched Microservices Journal on the SYS-CON.com portal, featuring over 19,000 original articles, news stories, features, and blog entries. DevOps Journal is focused on this critical enterprise IT topic in the world of cloud computing. Microservices Journal offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. Follow new article posts on T...
SYS-CON Media announced today that @ThingsExpo Blog launched with 7,788 original stories. @ThingsExpo Blog offers top articles, news stories, and blog posts from the world's well-known experts and guarantees better exposure for its authors than any other publication. @ThingsExpo Blog can be bookmarked. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago.
SYS-CON Events announced today that CenturyLink, Inc., a leader in the network services market, has been named “Platinum Sponsor” of 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. CenturyLink is the third largest telecommunications company in the United States and is recognized as a leader in the network services market by technology industry analyst firms. The company is a global leader in cloud infrastructure and ...
A new definition of Big Data & the practical applications of the defined components & associated technical architecture models This presentation introduces a new definition of Big Data, along with the practical applications of the defined components and associated technical architecture models. In his session at Big Data Expo, Tony Shan will start with looking into the concept of Big Data and tracing back the first definition by Doug Laney, and then he will dive deep into the description of 3V...
SYS-CON Events announced today that MangoApps 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., and the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. MangoApps provides private all-in-one social intranets allowing workers to securely collaborate from anywhere in the world and from any device. Social, mobile, and eas...
The security devil is always in the details of the attack: the ones you've endured, the ones you prepare yourself to fend off, and the ones that, you fear, will catch you completely unaware and defenseless. The Internet of Things (IoT) is nothing if not an endless proliferation of details. It's the vision of a world in which continuous Internet connectivity and addressability is embedded into a growing range of human artifacts, into the natural world, and even into our smartphones, appliances, a...
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...
SYS-CON Events announced today that CodeFutures, a leading supplier of database performance tools, has been named a “Sponsor” of SYS-CON's 16th International Cloud Expo®, which will take place on June 9–11, 2015, at the Javits Center in New York, NY. CodeFutures is an independent software vendor focused on providing tools that deliver database performance tools that increase productivity during database development and increase database performance and scalability during production.
Containers and microservices have become topics of intense interest throughout the cloud developer and enterprise IT communities. Accordingly, attendees at the upcoming 16th Cloud Expo at the Javits Center in New York June 9-11 will find fresh new content in a new track called PaaS | Containers & Microservices Containers are not being considered for the first time by the cloud community, but a current era of re-consideration has pushed them to the top of the cloud agenda. With the launch ...
SYS-CON Events announced today the IoT Bootcamp – Jumpstart Your IoT Strategy, being held June 9–10, 2015, in conjunction with 16th Cloud Expo and Internet of @ThingsExpo at the Javits Center in New York City. This is your chance to jumpstart your IoT strategy. Combined with real-world scenarios and use cases, the IoT Bootcamp is not just based on presentations but includes hands-on demos and walkthroughs. We will introduce you to a variety of Do-It-Yourself IoT platforms including Arduino, Ras...
The only place to be June 9-11 is Cloud Expo & @ThingsExpo 2015 East at the Javits Center in New York City. Join us there as delegates from all over the world come to listen to and engage with speakers & sponsors from the leading Cloud Computing, IoT & Big Data companies. Cloud Expo & @ThingsExpo are the leading events covering the booming market of Cloud Computing, IoT & Big Data for the enterprise. Speakers from all over the world will be hand-picked for their ability to explore the economic...
Buzzword alert: Microservices and IoT at a DevOps conference? What could possibly go wrong? Join this panel of experts as they peel away the buzz and discuss the important architectural principles behind implementing IoT solutions for the enterprise. As remote IoT devices and sensors become increasingly intelligent, they become part of our distributed cloud environment, and we must architect and code accordingly. At the very least, you’ll have no problem filling in your buzzword bingo cards.
SOA Software has changed its name to Akana. With roots in Web Services and SOA Governance, Akana has established itself as a leader in API Management and is expanding into cloud integration as an alternative to the traditional heavyweight enterprise service bus (ESB). The company recently announced that it achieved more than 90% year-over-year growth. As Akana, the company now addresses the evolution and diversification of SOA, unifying security, management, and DevOps across SOA, APIs, microser...