Welcome!

Microservices Expo Authors: APM Blog, Elizabeth White, Liz McMillan, Pat Romanski, XebiaLabs Blog

Related Topics: Java IoT, Microservices Expo, IoT User Interface, Agile Computing

Java IoT: Article

Don’t Let Load Balancers Ruin Your Holiday Business

Proactive performance management

An eCommerce site that crashes seven times during the Christmas season being down for up to five hours each time it crashes is a site that loses a lot of money and reputation. It happened to one of our customers who told this story at our annual performance conference earlier this month. Among the several reasons that led to these crashes I want to share more details on one of them that I see more often with other websites as well. Load balancers on a round-robin instead of least-busy can easily lead to app server crashes caused by heap memory exhaustion. Let's dig into some details on how to identify these problems and how to avoid it.

The Symptom: Crashing Tomcat Instances
The website is deployed on six Tomcats with three front-end Apache Web Servers. During peak load hours individual Tomcat instances started showing growing response times and a growing number of requests in the Tomcat processing queue. After a while these instances crashed due to out-of-memory exceptions and with that also brought down the rest of the site as load couldn't be handled any more with the remaining servers. Figure 1 shows the actual flow of transactions through the system highlighting unevenly distributed response time in the application servers and functional errors being reported on all tiers (red-colored server icon):

Even with equally distributed load (Round Robin Load Balancer Setting) one of the Tomcats spiked in Response Time Contribution before crashing

Once the App Server started rejecting incoming connections we can observe the first ripple effect of errors. We can see a very high number of exceptions in the database layer, exceptions thrown between application tiers with the web app responding with HTTP 500s:

Within 30 minutes the application serves 43000 pages with an HTTP 500 Response correlating to Exceptions in the Database and Inter-Tier Communication

The Root Cause: Inefficient Database Statements and Connection Pool Usage
The exceptions caught in the Database Layer (JDBC) were already a very good hint of the root cause of this problem. A closer look at the Exceptions shows that connection pools are exhausted, which causes problems in the different components of the application:

Exhausted Connection Pool causes Exceptions that impact Data Access Layer as well as Widget Rendering

Looking at the performance breakdown by application layer reveals how much performance impact connection pooling has on the overall transaction response time:

Due to the connection pool problem a single request had to wait 3.8s on average to obtain a connection from the pool

Now - it was not only the size of the pool that was the problem - but - several very inefficient database statements that took long to execute for certain business transactions of the application. This caused the application server to hold on to the connection longer than normal. As the load balancer was configured with Round Robin the app server still got additional requests served. Eventually - just by the random nature of incoming requests - one app server received several of these requests that executed these inefficient database calls. Once the connection pool was exhausted the application started throwing exceptions that ultimately also led to a crash of the JVM. Once the first app server crashed, it didn't take too long to take the other app servers down as well.

The Solution: Optimizing App and Load Balancer
The problem was fixed by looking at the slowest database statements and optimizing them for performance by, e.g, adding indices on the database or making the SQL statements more efficient. They also optimized the pool size to accommodate the expected load during peak hours.

 

They started by optimizing SQL Statements that took long to execute and those that got executed several times within the same transaction

They also changed the load balancer setting from Round-Robin to Least-Busy, which was the preferred setting from the LB vendor but had simply forgotten to configure in the production environment.

The Result: Site Has Not Been Down Since
Since they made the changes to the application and the load balancer the site has never gone down since. Now - the next holiday season is coming up and they are ready for the next seasonal spikes. Even though they are really confident that everything will work without any problems, they learned their lesson and are approaching performance proactively through proper load testing.

Next Steps: Proactive Performance Management
The lesson learned was that these problems could have been found prior to the holiday shopping season by doing proper load testing. They did load testing before but never encountered this problem because of two reasons: 1) they didn't test using expected peak volumes for long enough sessions and 2) didn't use a tool that simulated real customer behavior variations (too few scripts and the scripts were too simple) that tested their highly interactive web site.

Their strategy for proactive performance management is that they:

  1. Perform load tests on the production system during low traffic hours (2 a.m.-6 a.m.), accepting the risk of minor sales losses in case of a crash, versus major sales losses during the holiday shopping season.
  2. Multiply the hourly load test volume by 2.5 since their actual peaks are 10 hours long.
  3. Use a load testing service that uses real browsers in different locations around the U.S.
  4. Use an APM solution that identifies problems within the application while running the load test.

If you want to read more on common performance problems that are not found prior to moving to production check out my recent series of blogs: Supersized Content, Deployment Mistakes or Excessive Logging

More Stories By Michael Kopp

Michael Kopp has over 12 years of experience as an architect and developer in the Enterprise Java space. Before coming to CompuwareAPM dynaTrace he was the Chief Architect at GoldenSource, a major player in the EDM space. In 2009 he joined dynaTrace as a technology strategist in the center of excellence. He specializes application performance management in large scale production environments with special focus on virtualized and cloud environments. His current focus is how to effectively leverage BigData Solutions and how these technologies impact and change the application landscape.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@MicroservicesExpo Stories
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with the 19th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world and ThingsExpo Silicon Valley Call for Papers is now open.
While DevOps promises a better and tighter integration among an organization’s development and operation teams and transforms an application life cycle into a continual deployment, Chef and Azure together provides a speedy, cost-effective and highly scalable vehicle for realizing the business values of this transformation. In his session at @DevOpsSummit at 19th Cloud Expo, Yung Chou, a Technology Evangelist at Microsoft, will present a unique opportunity to witness how Chef and Azure work tog...
When scaling agile / Scrum, we invariable run into the alignment vs autonomy problem. In short: you cannot have autonomous self directing teams if they have no clue in what direction they should go, or even shorter: Alignment breeds autonomy. But how do we create alignment? and what tools can we use to quickly evaluate if what we want to do is part of the mission or better left out? Niel Nickolaisen created the Purpose Alignment model and I use it with innovation labs in large enterprises to de...
In his general session at 18th Cloud Expo, Lee Atchison, Principal Cloud Architect and Advocate at New Relic, discussed cloud as a ‘better data center’ and how it adds new capacity (faster) and improves application availability (redundancy). The cloud is a ‘Dynamic Tool for Dynamic Apps’ and resource allocation is an integral part of your application architecture, so use only the resources you need and allocate /de-allocate resources on the fly.
Using new techniques of information modeling, indexing, and processing, new cloud-based systems can support cloud-based workloads previously not possible for high-throughput insurance, banking, and case-based applications. In his session at 18th Cloud Expo, John Newton, CTO, Founder and Chairman of Alfresco, described how to scale cloud-based content management repositories to store, manage, and retrieve billions of documents and related information with fast and linear scalability. He addres...
SYS-CON Events announced today that Numerex Corp, a leading provider of managed enterprise solutions enabling the Internet of Things (IoT), will exhibit at the 19th International Cloud Expo | @ThingsExpo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Numerex Corp. (NASDAQ:NMRX) is a leading provider of managed enterprise solutions enabling the Internet of Things (IoT). The Company's solutions produce new revenue streams or create operating...
Analysis of 25,000 applications reveals 6.8% of packages/components used included known defects. Organizations standardizing on components between 2 - 3 years of age can decrease defect rates substantially. Open source and third-party packages/components live at the heart of high velocity software development organizations. Today, an average of 106 packages/components comprise 80 - 90% of a modern application, yet few organizations have visibility into what components are used where.
SYS-CON Events announced today that Tintri Inc., a leading producer of VM-aware storage (VAS) for virtualization and cloud environments, will exhibit at the 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Tintri VM-aware storage is the simplest for virtualized applications and cloud. Organizations including GE, Toyota, United Healthcare, NASA and 6 of the Fortune 15 have said “No to LUNs.” With Tintri they mana...
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, will compare the Jevons Paradox to modern-day enterprise IT, e...
Throughout history, various leaders have risen up and tried to unify the world by conquest. Fortunately, none of their plans have succeeded. The world goes on just fine with each country ruling itself; no single ruler is necessary. That’s how it is with the container platform ecosystem, as well. There’s no need for one all-powerful, all-encompassing container platform. Think about any other technology sector out there – there are always multiple solutions in every space. The same goes for conta...
SYS-CON Events announced today the Enterprise IoT Bootcamp, being held November 1-2, 2016, in conjunction with 19th Cloud Expo | @ThingsExpo at the Santa Clara Convention Center in Santa Clara, CA. Combined with real-world scenarios and use cases, the Enterprise IoT Bootcamp is not just based on presentations but with hands-on demos and detailed walkthroughs. We will introduce you to a variety of real world use cases prototyped using Arduino, Raspberry Pi, BeagleBone, Spark, and Intel Edison. Y...
Let's recap what we learned from the previous chapters in the series: episode 1 and episode 2. We learned that a good rollback mechanism cannot be designed without having an intimate knowledge of the application architecture, the nature of your components and their dependencies. Now that we know what we have to restore and in which order, the question is how?
Whether they’re located in a public, private, or hybrid cloud environment, cloud technologies are constantly evolving. While the innovation is exciting, the end mission of delivering business value and rapidly producing incremental product features is paramount. In his session at @DevOpsSummit at 19th Cloud Expo, Kiran Chitturi, CTO Architect at Sungard AS, will discuss DevOps culture, its evolution of frameworks and technologies, and how it is achieving maturity. He will also cover various st...
If you’re responsible for an application that depends on the data or functionality of various IoT endpoints – either sensors or devices – your brand reputation depends on the security, reliability, and compliance of its many integrated parts. If your application fails to deliver the expected business results, your customers and partners won't care if that failure stems from the code you developed or from a component that you integrated. What can you do to ensure that the endpoints work as expect...
Enterprise IT has been in the era of Hybrid Cloud for some time now. But it seems most conversations about Hybrid are focused on integrating AWS, Microsoft Azure, or Google ECM into existing on-premises systems. Where is all the Private Cloud? What do technology providers need to do to make their offerings more compelling? How should enterprise IT executives and buyers define their focus, needs, and roadmap, and communicate that clearly to the providers?
More and more companies are looking to microservices as an architectural pattern for breaking apart applications into more manageable pieces so that agile teams can deliver new features quicker and more effectively. What this pattern has done more than anything to date is spark organizational transformations, setting the foundation for future application development. In practice, however, there are a number of considerations to make that go beyond simply “build, ship, and run,” which changes ho...
SYS-CON Events announced today that eCube Systems, a leading provider of middleware modernization, integration, and management solutions, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. eCube Systems offers a family of middleware evolution products and services that maximize return on technology investment by leveraging existing technical equity to meet evolving business needs. ...
SYS-CON Events announced today that Commvault, a global leader in enterprise data protection and information management, has been named “Bronze Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Commvault is a leading provider of data protection and information management solutions, helping companies worldwide activate their data to drive more value and business insight and to transform moder...
The many IoT deployments around the world are busy integrating smart devices and sensors into their enterprise IT infrastructures. Yet all of this technology – and there are an amazing number of choices – is of no use without the software to gather, communicate, and analyze the new data flows. Without software, there is no IT. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists will look at the protocols that communicate data and the emerging data analy...
Large enterprises today are juggling an enormous variety of network equipment. Business users are asking for specific network throughput guarantees when it comes to their critical applications, legal departments require compliance with mandated regulatory frameworks, and operations are asked to do more with shrinking budgets. All these requirements do not easily align with existing network architectures; hence, network operators are continuously faced with a slew of granular parameter change req...