Welcome!

Java IoT Authors: Automic Blog, Liz McMillan, Elizabeth White, Pat Romanski, Roger Strukhoff

Related Topics: Java IoT, Industrial IoT, Microservices Expo, Open Source Cloud, @CloudExpo, Apache

Java IoT: Article

Tracing Black Boxes II: Monitoring Solr

Providing insight into Apache Solr instances by correlating individual traces with JMX metrics

Your site is indexed on Google, but that doesn't mean you're done with search. Content-rich websites provide native search functionality to keep users engaged, maintain visual consistency, and provide content-aware filtering. But it's very hard to implement an effective, scalable search system, which is why Apache Solr is just about the most popular ‘black box' in web application infrastructure. This Lucene-backed search appliance has seen wide adoption due to its performance, reliability, and ease of deployment. In fact, it's become so widely used that many Solr deployments are managed by people who have no other exposure to running Java applications. Documents go in, indexed RESTful search comes out - that is, until something breaks.

TraceView can provide insight into Apache Solr instances by correlating individual traces with JMX metrics, such as the rate of requests over the past 5 minutes. Even at a very low overall volume, an increased traffic rate is already increasing request latency.

TraceView can provide insight into Apache Solr instances by correlating individual traces with JMX metrics, such as the rate of requests over the past 5 minutes. Even at a very low overall volume, an increased traffic rate is already increasing request latency.

Unlike most web application front-ends, Solr is a complex, stateful application that contains persistent objects, runs background indexing processes, and maintains multiple tiers of caches. There are a lot of ways to deploy and configure Solr, and that means there are a lot of ways to make mistakes. But even when you have everything up and running, there's always the lingering question of whether you could be getting more out of your Solr instances (or reducing the number of them!).

One of the best ways to get insight into Solr's internal abstractions - such as cores, handlers, and components - is to monitor them directly via JMX. I've previously written about using JMX metrics to keep tabs on JVM memory internals, but JMX is a common API for collecting data from your Java applications and any application can make use of it. Because of this it's been widely adopted in the Java ecosystem to centralize the provision of application-specific performance data.

Solr provides JMX metrics on a variety of internals, such as queryResultCache.

 

Solr provides JMX metrics on a variety of internals, such as queryResultCache.

 

Solr exposes hundreds of JMX metrics across dozens of categories, and efficient use of them can help you delve into Solr performance in a variety of ways. Some metrics are better for providing a high-level view of Solr's overall workflow. The queryResultCachecategory, pictured above, provides a snapshot of how often your data was successfully cached, as well as how often cache entries had to be evicted due to insufficient space. Other metric categories are more granular and provide detail at the level of classes, or even objects. An update request will be routed to a different handler depending on whether the data was provided in XML, CSV, or JSON; each of these update handlers exposes metrics independently, like how long it has been running and the number of errors.

JMX metrics can even provide insight into advanced Solr use cases, like modifying result scoring to permit n-dimensional spatial searches or customizing results based on user data stored in Redis. Even without adding custom JMX metrics, Solr will report enough data to allow you to separately track the effectiveness of these custom searches relative to more traditional queries.

Let's look at a practical example. You just got paged because half of your distributed Solr cluster lost connectivity in a widespread EC2 outage. It looks like it might last a while, so you decide to add additional capacity in one of the functioning availability zones. Rather than spending time re-indexing your content, you decide to replicate your existing Solr data to the new servers. Using the high-level metrics provided byReplicationHandler, you determine that replication is proceeding smoothly. Halfway through your second replication, though, you realize that the first replicated server is taking five times as long as your original servers to respond to the same user queries, even though it's running on the same hardware. Checking out the cache metrics for a specific search handler, it looks like the hit ratios on its caches are abysmal - but wait, what's actually in those caches? After checking the metrics for that node's active Searcher instance, you realize you didn't set up Solr to warm the cache - it was starting off empty! Now you know to make a quick configuration change next time you spin up an instance so that the first users routed to it will have acceptable performance.

So, that sounds awesome - but how do you do it? The easiest approach is to view Solr's JMX statistics through its web interface (in Solr 3.x,
it's at /solr/admin/stats.jsp, while in Solr 4.x it's available at a collection-based URL like /solr/#/collection1/plugins/). However, web access won't be an option for most deployments. Alternately, you could use remote jconsole, but that requires either a complex remote configuration that's a tremendous hassle to set up or the glacially slow option of SSH X11 forwarding (e.g., ssh -X solr jconsole).

In practice, those approaches all suck. Solr is stunningly verbose: it exposes hundreds of JMX metrics out of the box, and that number expands quickly as you add additional handlers and components. Purpose-built JMX monitoring tools like jconsole are great for browsing the available metrics to see what's available, but they're horrible for pulling out the ones you want in a hurry. They also allow ‘write' operations like initiating garbage collection or clearing caches - definitely not something you want to give out to every developer!

TraceView automatically monitors the JMX metrics of every node involved in this distributed Solr Cloud trace.

 

TraceView automatically monitors the JMX metrics of every node involved in this distributed Solr Cloud trace.

On a day to day basis, it's more common to read JMX metrics via automated, ‘read-only' monitoring tools like NagiosGanglia, or AppNeta TraceView. These tools not only present a number of metrics at once, but they also generally let you filter down to a meaningful subset of the hundreds of lines exposed by Solr. On the other hand, "health check"-style metrics aren't necessarily the only way to look the problem. Each request has a number of metrics it can generate, and bringing together these data sources in one application has some real advantages. Looking at an individual request can tell you exactly what went wrong, it's often the context of JMX data that says why. Examining the concurrent host activity can disambiguate between whether a pause was due to a garbage collection event in the JVM or an overloaded document cache in Solr forcing additional disk access.

Next time, we'll talk about how TraceView captures these request-based metrics directly from the Solr internals. In the meantime, if you've got a Solr installation, sign up for your free account, put in on that server, and take a look inside that black box!

More Stories By James Meickle

James started as a hobbyist web developer, even though his academic background is in social psychology and political science. Lately his interests as a professional Drupal developer have migrated towards performance, security, and automation. His favorite languages is Python, his favorite editor is Sublime, and his favorite game is Dwarf Fortress.

@ThingsExpo Stories
Nordstrom is transforming the way that they do business and the cloud is the key to enabling speed and hyper personalized customer experiences. In his session at 21st Cloud Expo, Ken Schow, VP of Engineering at Nordstrom, discussed some of the key learnings and common pitfalls of large enterprises moving to the cloud. This includes strategies around choosing a cloud provider(s), architecture, and lessons learned. In addition, he covered some of the best practices for structured team migration an...
Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, discussed how they built...
In his session at 21st Cloud Expo, Raju Shreewastava, founder of Big Data Trunk, provided a fun and simple way to introduce Machine Leaning to anyone and everyone. He solved a machine learning problem and demonstrated an easy way to be able to do machine learning without even coding. Raju Shreewastava is the founder of Big Data Trunk (www.BigDataTrunk.com), a Big Data Training and consulting firm with offices in the United States. He previously led the data warehouse/business intelligence and B...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, examined the regulations and provided insight on how it affects technology, challenges the established rules and will usher in new levels of diligence arou...
The 22nd International Cloud Expo | 1st DXWorld Expo has announced that its Call for Papers is open. Cloud Expo | DXWorld Expo, to be held June 5-7, 2018, at the Javits Center in New York, NY, brings together Cloud Computing, Digital Transformation, Big Data, Internet of Things, DevOps, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...
Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
No hype cycles or predictions of a gazillion things here. IoT is here. You get it. You know your business and have great ideas for a business transformation strategy. What comes next? Time to make it happen. In his session at @ThingsExpo, Jay Mason, an Associate Partner of Analytics, IoT & Cybersecurity at M&S Consulting, presented a step-by-step plan to develop your technology implementation strategy. He also discussed the evaluation of communication standards and IoT messaging protocols, data...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
DevOps at Cloud Expo – being held June 5-7, 2018, at the Javits Center in New York, NY – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Among the proven benefits,...
@DevOpsSummit at Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, is co-located with 22nd Cloud Expo | 1st DXWorld Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait...
Cloud Expo | DXWorld Expo have announced the conference tracks for Cloud Expo 2018. Cloud Expo will be held June 5-7, 2018, at the Javits Center in New York City, and November 6-8, 2018, at the Santa Clara Convention Center, Santa Clara, CA. Digital Transformation (DX) is a major focus with the introduction of DX Expo within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive ov...
SYS-CON Events announced today that T-Mobile exhibited at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. As America's Un-carrier, T-Mobile US, Inc., is redefining the way consumers and businesses buy wireless services through leading product and service innovation. The Company's advanced nationwide 4G LTE network delivers outstanding wireless experiences to 67.4 million customers who are unwilling to compromise on qua...
SYS-CON Events announced today that Cedexis will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Cedexis is the leader in data-driven enterprise global traffic management. Whether optimizing traffic through datacenters, clouds, CDNs, or any combination, Cedexis solutions drive quality and cost-effectiveness. For more information, please visit https://www.cedexis.com.
SYS-CON Events announced today that Google Cloud has been named “Keynote Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Companies come to Google Cloud to transform their businesses. Google Cloud’s comprehensive portfolio – from infrastructure to apps to devices – helps enterprises innovate faster, scale smarter, stay secure, and do more with data than ever before.
SYS-CON Events announced today that Vivint to exhibit at SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California. As a leading smart home technology provider, Vivint offers home security, energy management, home automation, local cloud storage, and high-speed Internet solutions to more than one million customers throughout the United States and Canada. The end result is a smart home solution that sav...
SYS-CON Events announced today that Opsani will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Opsani is the leading provider of deployment automation systems for running and scaling traditional enterprise applications on container infrastructure.
SYS-CON Events announced today that Nirmata will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Nirmata provides a comprehensive platform, for deploying, operating, and optimizing containerized applications across clouds, powered by Kubernetes. Nirmata empowers enterprise DevOps teams by fully automating the complex operations and management of application containers and its underlying ...
SYS-CON Events announced today that Opsani to exhibit at SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California. Opsani is creating the next generation of automated continuous deployment tools designed specifically for containers. How is continuous deployment different from continuous integration and continuous delivery? CI/CD tools provide build and test. Continuous Deployment is the means by which...