Click here to close now.



Welcome!

Microservices Expo Authors: Jason Bloomberg, Elizabeth White, Anders Wallgren, Pat Romanski, Cloud Best Practices Network

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
If we look at slow, traditional IT and jump to the conclusion that just because we found its issues intractable before, that necessarily means we will again, then it’s time for a rethink. As a matter of fact, the world of IT has changed over the last ten years or so. We’ve been experiencing unprecedented innovation across the board – innovation in technology as well as in how people organize and accomplish tasks. Let’s take a look at three differences between today’s modern, digital context...
The battle over bimodal IT is heating up. Now that there’s a reasonably broad consensus that Gartner’s advice about bimodal IT is deeply flawed – consensus everywhere except perhaps at Gartner – various ideas are springing up to fill the void. The bimodal problem, of course, is well understood. ‘Traditional’ or ‘slow’ IT uses hidebound, laborious processes that would only get in the way of ‘fast’ or ‘agile’ digital efforts. The result: incoherent IT strategies and shadow IT struggles that lead ...
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 18th International Cloud Expo, which will take place on June 7–9, 2016, at the Javits Center in New York City, NY, and the 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...
As software organizations continue to invest in achieving Continuous Delivery (CD) of their applications, we see increased interest in microservices architectures, which–on the face of it–seem like a natural fit for enabling CD. In microservices (or its predecessor, “SOA”), the business functionality is decomposed into a set of independent, self-contained services that communicate with each other via an API. Each of the services has their own application release cycle, and are developed and depl...
SYS-CON Events announced today that Alert Logic, Inc., the leading provider of Security-as-a-Service solutions for the cloud, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. Alert Logic, Inc., provides Security-as-a-Service for on-premises, cloud, and hybrid infrastructures, delivering deep security insight and continuous protection for customers at a lower cost than traditional security solutions. Ful...
At the heart of the Cloud Native model is a microservices application architecture, and applying this to a telco SDN scenario offers enormous opportunity for product innovation and competitive advantage. For example in the ETSI NFV Ecosystem white paper they describe one of the product markets that SDN might address to be the Home sector. Vendors like Alcatel market SDN-based solutions for the home market, offering Home Gateways – A virtual residential gateway (vRGW) where service provider...
SYS-CON Events announced today that VAI, a leading ERP software provider, will exhibit at SYS-CON's 18th International Cloud Expo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. VAI (Vormittag Associates, Inc.) is a leading independent mid-market ERP software developer renowned for its flexible solutions and ability to automate critical business functions for the distribution, manufacturing, specialty retail and service sectors. An IBM Premier Business Part...
SYS-CON Events announced today that Catchpoint Systems, Inc., a provider of innovative web and infrastructure monitoring solutions, has been named “Silver Sponsor” of SYS-CON's DevOps Summit at 18th Cloud Expo New York, which will take place June 7-9, 2016, at the Javits Center in New York City, NY. Catchpoint is a leading Digital Performance Analytics company that provides unparalleled insight into customer-critical services to help consistently deliver an amazing customer experience. Designed...
SYS-CON Events announced today that AppNeta, the leader in performance insight for business-critical web applications, will exhibit and present at SYS-CON's @DevOpsSummit at Cloud Expo New York, which will take place on June 7-9, 2016, at the Javits Center in New York City, NY. AppNeta is the only application performance monitoring (APM) company to provide solutions for all applications – applications you develop internally, business-critical SaaS applications you use and the networks that deli...
In the Bimodal model we find two areas of IT - the traditional kind where the main concern is keeping the lights on and the IT focusing on agility and speed, where everything needs to be faster. Today companies are investing in new technologies and processes to emulate their most agile competitors. Gone are the days of waterfall development and releases only every few months. Today's IT and the business it powers demands performance akin to a supercar - everything needs to be faster, every sc...
The (re?)emergence of Microservices was especially prominent in this week’s news. What are they good for? do they make sense for your application? should you take the plunge? and what do Microservices mean for your DevOps and Continuous Delivery efforts? Continue reading for more on Microservices, containers, DevOps culture, and more top news from the past week. As always, stay tuned to all the news coming from@ElectricCloud on DevOps and Continuous Delivery throughout the week and retweet/favo...
In most cases, it is convenient to have some human interaction with a web (micro-)service, no matter how small it is. A traditional approach would be to create an HTTP interface, where user requests will be dispatched and HTML/CSS pages must be served. This approach is indeed very traditional for a web site, but not really convenient for a web service, which is not intended to be good looking, 24x7 up and running and UX-optimized. Instead, talking to a web service in a chat-bot mode would be muc...
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 Interoute, owner-operator of one of Europe's largest networks and a global cloud services platform, has been named “Bronze Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2015 at the Javits Center in New York, New York. Interoute is the owner-operator of one of Europe's largest networks and a global cloud services platform which encompasses 12 data centers, 14 virtual data centers and 31 colocation centers, with connections to 195 ad...
With microservices, SOA and distributed architectures becoming more popular, it is becoming increasingly harder to keep track of where time is spent in a distributed application when trying to diagnose performance problems. Distributed tracing systems attempt to address this problem by following application requests across service boundaries, persisting metadata along the way that provide context for fine-grained performance monitoring.
Web performance issues and advances have been gaining a stronger presence in the headlines as people are becoming more aware of its impact on virtually every business, and 2015 was no exception. We saw a myriad of major outages this year hit some of the biggest corporations, as well as some technology integrations and other news that we IT Ops aficionados find very exciting. This past year has offered several opportunities for growth and evolution in the performance realm — even the worst failu...
Are you someone who knows that the number one rule in DevOps is “Don’t Panic”? Especially when it comes to making Continuous Delivery changes inside your organization? Are you someone that theorizes that if anyone implements real automation changes, the solution will instantly become antiquated and be replaced by something even more bizarre and inexplicable?
Welcome to the first top DevOps news roundup of 2016! At the end of last year, we saw some great predictions for 2016. While we’re excited to kick off the new year, this week’s top posts reminded us to take a second to slow down and really understand the current state of affairs. For example, do you actually know what microservices are – or aren’t? What about DevOps? Does the emphasis still fall mostly on the development side? This week’s top news definitely got the wheels turning and just migh...
Test automation is arguably the most important innovation to the process of QA testing in software development. The ability to automate regression testing and other repetitive test cases can significantly reduce the overall production time for even the most complex solutions. As software continues to be developed for new platforms – including mobile devices and the diverse array of endpoints that will be created during the rise of the Internet of Things - automation integration will have a huge ...
I recently spotted a five-year-old blog post by Mike Gualtieri of Forrester, where he suggests firing your quality assurance (QA) team to improve your quality. He got the idea from a client who actually tried and succeeded with this counterintuitive move. The thinking goes that without a QA team to cover for them, developers are more likely to take care of quality properly – or risk getting the dreaded Sunday morning wakeup call to fix something. Gualtieri’s post generated modest buzz at th...