Click here to close now.

Welcome!

AJAX & REA Authors: Yakov Fain, Elizabeth White, Dana Gardner, VictorOps Blog, Liz McMillan

Related Topics: AJAX & REA, Java, XML, SOA & WOA, .NET, Cloud Expo

AJAX & REA: Article

Diagnosing Stuck Transactions in Minutes

A Step-by-Step Guide

Does the following situation sound familiar? From one minute to the other, your production servers grind to a halt, terse emails are complemented by equally hectic phone calls, and the first order of business is to get back up and running. After the dust settles, you're usually left with a pile of log files and the assignment of figuring out what happened, why it happened, and what to do to keep it from happening again.

A common first step is trying to reproduce what has gone wrong. More often than not, this consumes a considerable amount of time that would be better spent on actually fixing the problem. In this first blog post of a series, I will present a Step-by-Step Guide to Diagnose Stuck Transactions within minutes and show how a modern APM Solution helps to pinpoint common production problems, without spending hours on reproducing it at first.

The Problem: Response Time Increases
One of our customers deployed a new version of their prime web application and, for the first couple of days, everything seemed fine. One evening, their operations team was alerted about significantly increasing response time, and upon further investigation they recognized that a Stuck Transaction was blocking their application. While restarting the server solved the problem from an operations perspective it is not a long term solution as currently processing transactions get canceled and users are thrown off the system.

Their APM solution automatically captures thread dumps in case of too long running or stuck transactions. These dumps assist developers with diagnosing the issue. Let's take this example and walk through one of the problems often seen in a production environment: Diagnosing Stuck Transactions and Identifying the Root Cause.

Step 1: Identify problematic JVM/CLR
To identify the correct thread dump to analyze, it's important to know which server was affected by the stuck transaction and at what time that happened.

The transaction flow indicates a problem on one of the application servers

When drilling to the actual transactions that flow through that application server and focusing on the timeframe just before the server got restarted, I noticed a timed-out PurePath that spent 100% in sync time. This means that all it did was wait for one or more monitors, which makes it a likely culprit for our stuck transaction.

The PurePath reveals the information about which Application Server (=Agent) was involved in that stuck transaction

Step 2: Identify blocked threads
Having identified the affected application server, we can browse the list of available thread dumps and open the corresponding one.

Thread dump overview on runnable, blocked, waiting and timed waiting threads

When looking at the thread dump, threads can be grouped by their state to get a quick overview on how many threads the application executed when the dump was performed and how many of them were actually blocked. In this case, we are looking at four threads as Figure 4 shows.

Out of the 600+ Threads in the application, 4 are blocked and subject for further investigation

Step 3: Identify root cause
Already the first one of these threads is the thread from our timed-out PurePath we looked at in Step 1 - identifiable by its ID. We also get the most important piece of information we need to identify the root cause: Which object is this thread waiting on, and who owns it?

We now know which method is blocking and that it is blocked because it waits for an object owned by another thread -> a potential deadlock?

Usually, the thread owning the object we are waiting for is highlighted in red. Given the number of threads in this dump, it's unlikely to spot it this way, but search for the ID of the owning thread giving us the following information:

The HistoryLayout thread owns a monitor object with two waiting threads, which causes the web request handler to block and run into a timeout for the end user - the deadlock is identified!

In this case, the method com.vaadin.ui.Table.unregisterPropertiesAndComponents is working on the same instance of ConfigurableReportsApplication that AbstractApplicationPortlet.handleRequest is waiting for. Having identified the thread, we have the full stack trace at hand in the lower pane, and can track down how this situation occurred.

Conclusion
Trying to reproduce such concurrency-related problems on a developer machine with typically requires a major effort. If your APM tool fully supports collaboration between teams, all analysis steps described above can be performed in your local environment, without direct access to production servers. Using an APM Solution like dynaTrace, it only took a couple of minutes to answer the crucial questions named above: we know exactly what happened and how it happened, and are thus also able to modify our application in a way to avoid this situation in the future.

More Stories By Wolfgang Gottesheim

Wolfgang Gottesheim has several years of experience as a software engineer and research assistant in the Java enterprise space. Currently he contributes to the strategic development of the dynaTrace enterprise solution as a Technology Strategy in the Compuware APM division’s Center of Excellence. He focuses on monitoring and optimizing applications in production.

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.


@CloudExpo Stories
PubNub on Monday has announced that it is partnering with IBM to bring its sophisticated real-time data streaming and messaging capabilities to Bluemix, IBM’s cloud development platform. “Today’s app and connected devices require an always-on connection, but building a secure, scalable solution from the ground up is time consuming, resource intensive, and error-prone,” said Todd Greene, CEO of PubNub. “PubNub enables web, mobile and IoT developers building apps on IBM Bluemix to quickly add sc...
Data-intensive companies that strive to gain insights from data using Big Data analytics tools can gain tremendous competitive advantage by deploying data-centric storage. Organizations generate large volumes of data, the vast majority of which is unstructured. As the volume and velocity of this unstructured data increases, the costs, risks and usability challenges associated with managing the unstructured data (regardless of file type, size or device) increases simultaneously, including end-to-...
The excitement around the possibilities enabled by Big Data is being tempered by the daunting task of feeding the analytics engines with high quality data on a continuous basis. As the once distinct fields of data integration and data management increasingly converge, cloud-based data solutions providers have emerged that can buffer your organization from the complexities of this continuous data cleansing and management so that you’re free to focus on the end goal: actionable insight.
With several hundred implementations of IoT-enabled solutions in the past 12 months alone, this session will focus on experience over the art of the possible. Many can only imagine the most advanced telematics platform ever deployed, supporting millions of customers, producing tens of thousands events or GBs per trip, and hundreds of TBs per month. With the ability to support a billion sensor events per second, over 30PB of warm data for analytics, and hundreds of PBs for an data analytics arc...
Between the compelling mockups and specs produced by your analysts and designers, and the resulting application built by your developers, there is a gulf where projects fail, costs spiral out of control, and applications fall short of requirements. In his session at DevOps Summit, Charles Kendrick, CTO and Chief Architect at Isomorphic Software, will present a new approach where business and development users collaborate – each using tools appropriate to their goals and expertise – to build mo...
The Internet of Things (IoT) is causing data centers to become radically decentralized and atomized within a new paradigm known as “fog computing.” To support IoT applications, such as connected cars and smart grids, data centers' core functions will be decentralized out to the network's edges and endpoints (aka “fogs”). As this trend takes hold, Big Data analytics platforms will focus on high-volume log analysis (aka “logs”) and rely heavily on cognitive-computing algorithms (aka “cogs”) to mak...
Since 2008 and for the first time in history, more than half of humans live in urban areas, urging cities to become “smart.” Today, cities can leverage the wide availability of smartphones combined with new technologies such as Beacons or NFC to connect their urban furniture and environment to create citizen-first services that improve transportation, way-finding and information delivery. In her session at @ThingsExpo, Laetitia Gazel-Anthoine, CEO of Connecthings, will focus on successful use c...
SYS-CON Events announced today that GENBAND, a leading developer of real time communications software solutions, has been named “Silver Sponsor” of SYS-CON's WebRTC Summit, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. The GENBAND team will be on hand to demonstrate their newest product, Kandy. Kandy is a communications Platform-as-a-Service (PaaS) that enables companies to seamlessly integrate more human communications into their Web and mobile applicatio...
VictorOps is making on-call suck less with the only collaborative alert management platform on the market. With easy on-call scheduling management, a real-time incident timeline that gives you contextual relevance around your alerts and powerful reporting features that make post-mortems more effective, VictorOps helps your IT/DevOps team solve problems faster.
Skeuomorphism usually means retaining existing design cues in something new that doesn’t actually need them. However, the concept of skeuomorphism can be thought of as relating more broadly to applying existing patterns to new technologies that, in fact, cry out for new approaches. In his session at DevOps Summit, Gordon Haff, Senior Cloud Strategy Marketing and Evangelism Manager at Red Hat, will discuss why containers should be paired with new architectural practices such as microservices ra...
Roberto Medrano, Executive Vice President at SOA Software, had reached 30,000 page views on his home page - http://RobertoMedrano.SYS-CON.com/ - on the SYS-CON family of online magazines, which includes Cloud Computing Journal, Internet of Things Journal, Big Data Journal, and SOA World Magazine. He is a recognized executive in the information technology fields of SOA, internet security, governance, and compliance. He has extensive experience with both start-ups and large companies, having been ...
Companies today struggle to manage the types and volume of data their customers and employees generate and use every day. With billions of requests daily, operational consistency can be elusive. In his session at Big Data Expo, Dave McCrory, CTO at Basho Technologies, will explore how a distributed systems solution, such as NoSQL, can give organizations the consistency and availability necessary to succeed with on-demand data, offering high availability at massive scale.
From telemedicine to smart cars, digital homes and industrial monitoring, the explosive growth of IoT has created exciting new business opportunities for real time calls and messaging. In his session at @ThingsExpo, Ivelin Ivanov, CEO and Co-Founder of Telestax, shared some of the new revenue sources that IoT created for Restcomm – the open source telephony platform from Telestax. Ivelin Ivanov is a technology entrepreneur who founded Mobicents, an Open Source VoIP Platform, to help create, de...
The industrial software market has treated data with the mentality of “collect everything now, worry about how to use it later.” We now find ourselves buried in data, with the pervasive connectivity of the (Industrial) Internet of Things only piling on more numbers. There’s too much data and not enough information. In his session at @ThingsExpo, Bob Gates, Global Marketing Director, GE’s Intelligent Platforms business, to discuss how realizing the power of IoT, software developers are now focu...
Security can create serious friction for DevOps processes. We've come up with an approach to alleviate the friction and provide security value to DevOps teams. In her session at DevOps Summit, Shannon Lietz, Senior Manager of DevSecOps at Intuit, will discuss how DevSecOps got started and how it has evolved. Shannon Lietz has over two decades of experience pursuing next generation security solutions. She is currently the DevSecOps Leader for Intuit where she is responsible for setting and driv...
Operational Hadoop and the Lambda Architecture for Streaming Data Apache Hadoop is emerging as a distributed platform for handling large and fast incoming streams of data. Predictive maintenance, supply chain optimization, and Internet-of-Things analysis are examples where Hadoop provides the scalable storage, processing, and analytics platform to gain meaningful insights from granular data that is typically only valuable from a large-scale, aggregate view. One architecture useful for capturing...
SYS-CON Events announced today that Vitria Technology, Inc. will exhibit at SYS-CON’s @ThingsExpo, which will take place on June 9-11, 2015, at the Javits Center in New York City, NY. Vitria will showcase the company’s new IoT Analytics Platform through live demonstrations at booth #330. Vitria’s IoT Analytics Platform, fully integrated and powered by an operational intelligence engine, enables customers to rapidly build and operationalize advanced analytics to deliver timely business outcomes ...
DevOps is about increasing efficiency, but nothing is more inefficient than building the same application twice. However, this is a routine occurrence with enterprise applications that need both a rich desktop web interface and strong mobile support. With recent technological advances from Isomorphic Software and others, it is now feasible to create a rich desktop and tuned mobile experience with a single codebase, without compromising performance or usability.
Thanks to Docker, it becomes very easy to leverage containers to build, ship, and run any Linux application on any kind of infrastructure. Docker is particularly helpful for microservice architectures because their successful implementation relies on a fast, efficient deployment mechanism – which is precisely one of the features of Docker. Microservice architectures are therefore becoming more popular, and are increasingly seen as an interesting option even for smaller projects, instead of bein...
SYS-CON Events announced today Arista Networks will exhibit at SYS-CON's DevOps Summit 2015 New York, which will take place June 9-11, 2015, at the Javits Center in New York City, NY. Arista Networks was founded to deliver software-driven cloud networking solutions for large data center and computing environments. Arista’s award-winning 10/40/100GbE switches redefine scalability, robustness, and price-performance, with over 3,000 customers and more than three million cloud networking ports depl...