|By Michael Kopp||
|November 4, 2012 09:00 AM EST||
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:
- 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.
- Multiply the hourly load test volume by 2.5 since their actual peaks are 10 hours long.
- Use a load testing service that uses real browsers in different locations around the U.S.
- 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
The IoT is changing the way enterprises conduct business. In his session at @ThingsExpo, Eric Hoffman, Vice President at EastBanc Technologies, discuss how businesses can gain an edge over competitors by empowering consumers to take control through IoT. We'll cite examples such as a Washington, D.C.-based sports club that leveraged IoT and the cloud to develop a comprehensive booking system. He'll also highlight how IoT can revitalize and restore outdated business models, making them profitable...
May. 29, 2016 02:00 PM EDT Reads: 2,955
The IoTs will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, will demonstrate how to move beyond today's coding paradigm and share the must-have mindsets for removing complexity from the development proc...
May. 29, 2016 01:00 PM EDT Reads: 1,976
Customer experience has become a competitive differentiator for companies, and it’s imperative that brands seamlessly connect the customer journey across all platforms. With the continued explosion of IoT, join us for a look at how to build a winning digital foundation in the connected era – today and in the future. In his session at @ThingsExpo, Chris Nguyen, Group Product Marketing Manager at Adobe, will discuss how to successfully leverage mobile, rapidly deploy content, capture real-time d...
May. 29, 2016 12:45 PM EDT Reads: 1,675
SYS-CON Events announced today that ContentMX, the marketing technology and services company with a singular mission to increase engagement and drive more conversations for enterprise, channel and SMB technology marketers, has been named “Sponsor & Exhibitor Lounge Sponsor” of SYS-CON's 18th Cloud Expo, which will take place on June 7-9, 2016, at the Javits Center in New York City, New York. “CloudExpo is a great opportunity to start a conversation with new prospects, but what happens after the...
May. 29, 2016 10:30 AM EDT Reads: 1,301
What a difference a year makes. Organizations aren’t just talking about IoT possibilities, it is now baked into their core business strategy. With IoT, billions of devices generating data from different companies on different networks around the globe need to interact. From efficiency to better customer insights to completely new business models, IoT will turn traditional business models upside down. In the new customer-centric age, the key to success is delivering critical services and apps wit...
May. 29, 2016 10:30 AM EDT Reads: 1,271
Join us at Cloud Expo | @ThingsExpo 2016 – June 7-9 at the Javits Center in New York City and November 1-3 at the Santa Clara Convention Center in Santa Clara, CA – and deliver your unique message in a way that is striking and unforgettable by taking advantage of SYS-CON's unmatched high-impact, result-driven event / media packages.
May. 29, 2016 10:00 AM EDT Reads: 2,510
In his keynote at 18th Cloud Expo, Andrew Keys, Co-Founder of ConsenSys Enterprise, will provide an overview of the evolution of the Internet and the Database and the future of their combination – the Blockchain. Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life ...
May. 29, 2016 09:45 AM EDT Reads: 2,027
SYS-CON Events announced today that BMC Software has been named "Siver 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. BMC is a global leader in innovative software solutions that help businesses transform into digital enterprises for the ultimate competitive advantage. BMC Digital Enterprise Management is a set of innovative IT solutions designed to make digital business fast, seamless, and optimized from mainframe to mo...
May. 29, 2016 09:30 AM EDT Reads: 2,307
SYS-CON Events announced today that MobiDev 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. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex software systems for startups and enterprises. Since 2009 it has grown from a small group of passionate engineers and business managers to a full-scale mobile software company with over 200 develope...
May. 29, 2016 08:15 AM EDT Reads: 2,750
SoftLayer operates a global cloud infrastructure platform built for Internet scale. With a global footprint of data centers and network points of presence, SoftLayer provides infrastructure as a service to leading-edge customers ranging from Web startups to global enterprises. SoftLayer's modular architecture, full-featured API, and sophisticated automation provide unparalleled performance and control. Its flexible unified platform seamlessly spans physical and virtual devices linked via a world...
May. 29, 2016 07:00 AM EDT Reads: 2,304
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...
May. 29, 2016 06:45 AM EDT Reads: 2,956
Companies can harness IoT and predictive analytics to sustain business continuity; predict and manage site performance during emergencies; minimize expensive reactive maintenance; and forecast equipment and maintenance budgets and expenditures. Providing cost-effective, uninterrupted service is challenging, particularly for organizations with geographically dispersed operations.
May. 29, 2016 06:00 AM EDT Reads: 2,175
As cloud and storage projections continue to rise, the number of organizations moving to the cloud is escalating and it is clear cloud storage is here to stay. However, is it secure? Data is the lifeblood for government entities, countries, cloud service providers and enterprises alike and losing or exposing that data can have disastrous results. There are new concepts for data storage on the horizon that will deliver secure solutions for storing and moving sensitive data around the world. ...
May. 29, 2016 06:00 AM EDT Reads: 1,355
SYS-CON Events announced today TechTarget has been named “Media 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. TechTarget is the Web’s leading destination for serious technology buyers researching and making enterprise technology decisions. Its extensive global networ...
May. 29, 2016 05:15 AM EDT Reads: 3,274
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...
May. 29, 2016 04:30 AM EDT Reads: 3,255
SYS-CON Events announced today that MangoApps 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. MangoApps provides modern company intranets and team collaboration software, allowing workers to stay connected and productive from anywhere in the world and from any device. For more information, please visit https://www.mangoapps.com/.
May. 29, 2016 03:30 AM EDT Reads: 1,001
The essence of data analysis involves setting up data pipelines that consist of several operations that are chained together – starting from data collection, data quality checks, data integration, data analysis and data visualization (including the setting up of interaction paths in that visualization). In our opinion, the challenges stem from the technology diversity at each stage of the data pipeline as well as the lack of process around the analysis.
May. 29, 2016 02:45 AM EDT Reads: 1,502
Designing IoT applications is complex, but deploying them in a scalable fashion is even more complex. A scalable, API first IaaS cloud is a good start, but in order to understand the various components specific to deploying IoT applications, one needs to understand the architecture of these applications and figure out how to scale these components independently. In his session at @ThingsExpo, Nara Rajagopalan is CEO of Accelerite, will discuss the fundamental architecture of IoT applications, ...
May. 29, 2016 02:00 AM EDT Reads: 1,348
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 18th International CloudExpo®, which will take place on June 7-9, 2016, at the Javits Center in New York City, New York, 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.
May. 29, 2016 01:30 AM EDT Reads: 2,490
In his session at 18th Cloud Expo, Bruce Swann, Senior Product Marketing Manager at Adobe, will discuss how the Adobe Marketing Cloud can help marketers embrace opportunities for personalized, relevant and real-time customer engagement across offline (direct mail, point of sale, call center) and digital (email, website, SMS, mobile apps, social networks, connected objects). Bruce Swann has more than 15 years of experience working with digital marketing disciplines like web analytics, social med...
May. 29, 2016 01:00 AM EDT Reads: 1,434