Welcome!

Microservices Expo Authors: Jyoti Bansal, Automic Blog, Kong Yang, Yeshim Deniz, XebiaLabs Blog

Related Topics: Java IoT, Microservices Expo, ColdFusion, Microsoft Cloud, Machine Learning

Java IoT: Article

Load Testing in Clustered Environments

Clustered Environments: Load Testing for Architectural Validation (P.S. Don’t Extrapolate!)

Load and performance testing web applications will allow you to determine whether or not your deployment will require a clustered environment. When the test results show that the current throughput is restricted by the capacity of the server but target workloads are not yet met, this is a situation where you can achieve higher scalability by implementing clusters to your environment. Clustering achieves higher scalability by introducing more servers or nodes to expand the capacity of the environment. Obviously, the benefits of adding hardware include higher capacity, reliability, availability, and scalability. But also consider that clustering also adds complexity to your deployment by requiring added maintenance and an increased need for deployment/upgrade automation. To ensure quality of the environment you must always validate your clustered environment and prove out the increased scalability. Use a methodical performance testing approach. Don't try to extrapolate! It's not as easy as "3 nodes in a cluster will support 3x the workload."

Why Cluster?
An efficiently tuned deployment will, in turn, display an efficient use of server resources (memory, CPU, i/o, etc). Using a cluster increases the number of servers and distributes the workload amongst several servers. This even distribution of the workload can dramatically increase scalability. Not only can this improve the end user experience by reaching higher workloads with predictable response times but it can increase the reliability and stability of the deployment. The cluster acts as a single server so the loss or shutdown of any of the nodes in the cluster will not result in loss of sessions or application data. In the end, the user experience is less frequently interrupted and isn't affected by a single maxed out server or a loss of a server.

Tuning Tips
When performance or load testing your application uncovers a clear need to introduce clusters or farms to support the target workload, you will want to take into account the following considerations: First you should configure the cluster efficiently for internal maintenance such as data synchronization and heartbeat communications. User sessions which live in memory are more quickly failed over to another node in the cluster instead of persisting them to the database. However, writing the sessions to disk is more permanent which may have its own advantages. Make sure you have tested the performance prices for data synchronization and heartbeat communications. The goal is to configure the cluster to increase scalability with as little overhead as possible.

Load Balancers
Load balancers are generally placed out in front of the clusters. These load balancers can be a software solution or a hardware solution. Their job is to distribute the load evenly to the nodes in the cluster. Just as important, LB's reroute traffic when one node of the cluster goes down. This allows for the "transparency" of several servers acting as one. There are several more mature algorithms for distribution than traditional "round robins." Smarter LB's takes into account the CPU and resource usage and overall load of each server and their job is to direct the request to the least loaded server. The number of active users doesn't always equate to more resources being actively used, rather it depends on the types of transactions being executed - lightweight vs. expensive transactions. Smart LB's will detect workload and direct incoming traffic based on resource usage. Often LB's will use sticky sessions based on the client's cookie and/or IP address to route subsequent requests to the same node of cluster where the user session lives. Whenload testing these types of environments, it's a requirement to have a load tool which supports IP Spoofing. This is used to generate the load of many virtual users using multiple IP addresses all from a single machine. Otherwise, the total load would go to a single cluster node.

Types of Clustering
Clustering can be achieved using a few common techniques. Vertical clustering adds capacity to the deployment by installing multiple nodes of a cluster on a single machine. With this approach you must take into consideration the physical limitations of that machine (CPU, memory, i/o) and be careful not over utilize resources; otherwise adding more nodes becomes pointless due to saturation. Horizontal clusters refer to deploying more physical machines. With this approach, each physical machine can run one or more of the nodes of the cluster. Cloud bursting is a way of having a node both within the LAN and a node in the Cloud to be turned "on" during high volume usage or be strategically placed in different geographical locations. The appropriate technique really depends on the specifics of your environment. If you need more capacity and you have beefy infrastructure servers but do not have enough web servers or app servers to fully utilize the underlying hardware, choose the vertical clustering approach by adding more nodes to the same machine. On the other hand, if more physical resources are needed to handle the workload, then build out a horizontal cluster by adding more hardware and deploying more nodes.

How to Load Test a Cluster?
It's important to take a methodical approach to load testing a clustered environment. Load patterns such as ramping tests allow you to identify the current capacity as well as increased scalability as you add more nodes to the cluster. Remember that doubling the number of nodes in a cluster does not equate to doubling its capacity. Many components impact its performance gain such as the communications between the nodes used to just make the cluster work properly. The resource cost increases dramatically with the number of nodes. Capacity is relative and is dependent on myriad other components within the infrastructure. For example, adding another node to the cluster may give the application layer 2x the throughput (although this is not really possible due to "housekeeping" from internal administration overhead to maintain that cluster), but let's say the single webserver out front is already using all its worker threads, then requests will be queued while waiting for a thread to become available and overall throughput will not increase. Only through the analysis of load test results will you completely understand the increased scalability effects of a cluster. Consider another scenario: You have identified a need for building out a cluster of application servers, however you deploy too many nodes resulting in a backlog of requests on the shared database. Performance and load testing will uncover this vulnerability and many other potential scenarios that could otherwise go undetected. Having a comparison analysis feature built right into the load tool will allow you to run tests back to back, after turning on/off nodes in the cluster, and quickly visualize the differences. Also, having the tool with a built-in cloud load generation feature will save time and money setting up and maintaining the performance architecture environment, especially for high load tests.

The Right Approach?
Adding clustering to a deployment allows a web application to achieve higher workloads and gives the advantage of higher availability. However, you must conduct performance tests in order to build out an efficient cluster which meets your goals. Don't forget to weigh the benefits vs. added maintenance complexity/cost. Clusters require a high level of expertise to implement and maintain so they aren't the best solution in every situation. Make sure all moving parts are documented and insist on a complete architectural diagram for future systems administrators (diagrams to include hierarchical transaction pathways as well as location of each node in the cluster including the admin consoles). In the end it's all about delivering the best possible end user experience and in many cases clustering is an excellent solution for increasing scalability of your web deployments.

More Stories By Rebecca Clinard

Rebecca Clinard is a Senior Performance Engineer at Neotys, a provider of load testing software for Web applications. Previously, she worked as a web application performance engineer for Bowstreet, Fidelity Investments, Bottomline Technologies and Timberland companies, industries spanning retail, financial services, insurance and manufacturing. Her expertise lies in creating realistic load tests and performance tuning multi-tier deployments. She has been orchestrating and conducting performance tests since 2001. Clinard graduated from University of New Hampshire with a BS and also holds a UNIX Certificate from Worcester Polytechnic Institute.

@MicroservicesExpo Stories
Is your application too difficult to manage? Do changes take dozens of developers hundreds of hours to execute, and frequently result in downtime across all your site’s functions? It sounds like you have a monolith! A monolith is one of the three main software architectures that define most applications. Whether you’ve intentionally set out to create a monolith or not, it’s worth at least weighing the pros and cons of the different architectural approaches and deciding which one makes the most s...
In large enterprises, environment provisioning and server provisioning account for a significant portion of the operations team's time. This often leaves users frustrated while they wait for these services. For instance, server provisioning can take several days and sometimes even weeks. At the same time, digital transformation means the need for server and environment provisioning is constantly growing. Organizations are adopting agile methodologies and software teams are increasing the speed ...
To more closely examine the variety of ways in which IT departments around the world are integrating cloud services, and the effect hybrid IT has had on their organizations and IT job roles, SolarWinds recently released the SolarWinds IT Trends Report 2017: Portrait of a Hybrid Organization. This annual study consists of survey-based research that explores significant trends, developments, and movements related to and directly affecting IT and IT professionals.
Cloud Expo, Inc. has announced today that Aruna Ravichandran, vice president of DevOps Product and Solutions Marketing at CA Technologies, has been named co-conference chair of DevOps at Cloud Expo 2017. The @DevOpsSummit at Cloud Expo New York will take place on June 6-8, 2017, at the Javits Center in New York City, New York, and @DevOpsSummit at Cloud Expo Silicon Valley will take place Oct. 31-Nov. 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Developers want to create better apps faster. Static clouds are giving way to scalable systems, with dynamic resource allocation and application monitoring. You won't hear that chant from users on any picket line, but helping developers to create better apps faster is the mission of Lee Atchison, principal cloud architect and advocate at New Relic Inc., based in San Francisco. His singular job is to understand and drive the industry in the areas of cloud architecture, microservices, scalability ...
Back in February of 2017, Andrew Clay Schafer of Pivotal tweeted the following: “seriously tho, the whole software industry is stuck on deployment when we desperately need architecture and telemetry.” Intrigue in a 140 characters. For me, I hear Andrew saying, “we’re jumping to step 5 before we’ve successfully completed steps 1-4.”
This recent research on cloud computing from the Register delves a little deeper than many of the "We're all adopting cloud!" surveys we've seen. They found that meaningful cloud adoption and the idea of the cloud-first enterprise are still not reality for many businesses. The Register's stats also show a more gradual cloud deployment trend over the past five years, not any sort of explosion. One important takeaway is that coherence across internal and external clouds is essential for IT right n...
Enterprise architects are increasingly adopting multi-cloud strategies as they seek to utilize existing data center assets, leverage the advantages of cloud computing and avoid cloud vendor lock-in. This requires a globally aware traffic management strategy that can monitor infrastructure health across data centers and end-user experience globally, while responding to control changes and system specification at the speed of today’s DevOps teams. In his session at 20th Cloud Expo, Josh Gray, Chie...
Software as a service (SaaS), one of the earliest and most successful cloud services, has reached mainstream status. According to Cisco, by 2019 more than four-fifths (83 percent) of all data center traffic will be based in the cloud, up from 65 percent today. The majority of this traffic will be applications. Businesses of all sizes are adopting a variety of SaaS-based services – everything from collaboration tools to mission-critical commerce-oriented applications. The rise in SaaS usage has m...
The proper isolation of resources is essential for multi-tenant environments. The traditional approach to isolate resources is, however, rather heavyweight. In his session at 18th Cloud Expo, Igor Drobiazko, co-founder of elastic.io, drew upon his own experience with operating a Docker container-based infrastructure on a large scale and present a lightweight solution for resource isolation using microservices. He also discussed the implementation of microservices in data and application integrat...
We'd all like to fulfill that "find a job you love and you'll never work a day in your life" cliché. But in reality, every job (even if it's our dream job) comes with its downsides. For you, the constant fight against shadow IT might get on your last nerves. For your developer coworkers, infrastructure management is the roadblock that stands in the way of focusing on coding. As you watch more and more applications and processes move to the cloud, technology is coming to developers' rescue-most r...
2016 has been an amazing year for Docker and the container industry. We had 3 major releases of Docker engine this year , and tremendous increase in usage. The community has been following along and contributing amazing Docker resources to help you learn and get hands-on experience. Here’s some of the top read and viewed content for the year. Of course releases are always really popular, particularly when they fit requests we had from the community.
Keeping pace with advancements in software delivery processes and tooling is taxing even for the most proficient organizations. Point tools, platforms, open source and the increasing adoption of private and public cloud services requires strong engineering rigor – all in the face of developer demands to use the tools of choice. As Agile has settled in as a mainstream practice, now DevOps has emerged as the next wave to improve software delivery speed and output. To make DevOps work, organization...
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
Even for the most seasoned IT pros, the cloud is complicated. It can be difficult just to wrap your head around the many terms and acronyms that make up the cloud dictionary-not to mention actually mastering the technology. Unfortunately, complicated cloud terms are often combined to the point that their meanings are lost in a sea of conflicting opinions. Two terms that are used interchangeably (but shouldn't be) are hybrid cloud and multicloud. If you want to be the cloud expert your company ne...
In his general session at 19th Cloud Expo, Manish Dixit, VP of Product and Engineering at Dice, discussed how Dice leverages data insights and tools to help both tech professionals and recruiters better understand how skills relate to each other and which skills are in high demand using interactive visualizations and salary indicator tools to maximize earning potential. Manish Dixit is VP of Product and Engineering at Dice. As the leader of the Product, Engineering and Data Sciences team at D...
In his session at 20th Cloud Expo, Scott Davis, CTO of Embotics, will discuss how automation can provide the dynamic management required to cost-effectively deliver microservices and container solutions at scale. He will discuss how flexible automation is the key to effectively bridging and seamlessly coordinating both IT and developer needs for component orchestration across disparate clouds – an increasingly important requirement at today’s multi-cloud enterprise.
SYS-CON Events announced today that CollabNet, a global leader in enterprise software development, release automation and DevOps solutions, will be a Bronze Sponsor of SYS-CON's 20th International Cloud Expo®, taking place from June 6-8, 2017, at the Javits Center in New York City, NY. CollabNet offers a broad range of solutions with the mission of helping modern organizations deliver quality software at speed. The company’s latest innovation, the DevOps Lifecycle Manager (DLM), supports Value S...
The human body is the most complex machine ever created! With a complex network of interconnected organs, millions of cells and the most advanced processor, human body is the most automated system in this planet. In this article, we will draw comparisons between working of a human body to that of a datacenter. We will learn how self-defense and self-healing capabilities of our human body is similar to firewalls and intelligent monitoring capabilities in our datacenters. We will draw parallels b...
Cloud adoption is often driven by a desire to increase efficiency, boost agility and save money. All too often, however, the reality involves unpredictable cost spikes and lack of oversight due to resource limitations. In his session at 20th Cloud Expo, Joe Kinsella, CTO and Founder of CloudHealth Technologies, will tackle the question: “How do you build a fully optimized cloud?” He will examine: Why TCO is critical to achieving cloud success – and why attendees should be thinking holisticall...