5 Steps to Enhance APM with Log Data
May 20, 2014
Trevor Parsons
Share this

Logs have moved beyond a basic tool for debugging during development. A recent Logentries survey carried out across a sample of 25k users of log management software shows that the most common use case is using log data for production monitoring, which has traditionally been the stronghold of Application Performance Management (APM) and server monitoring tools.

Using logs for application monitoring comes with a major benefit. Logs not only allow you to look at trends in your data, but – unlike APM or server monitoring tools – they also maintain the evidence so that you can drill down to the log event level to understand exactly what led to a spike in response time or CPU for example.

Furthermore, you can also use logs to be proactive, such that you can create notifications or automated actions when particular events occur or thresholds are breached. That way you can get notified and react when symptoms of more serious issues begin to occur so you can react before a major incident happens.

So what are the most important steps to follow to investigate and resolve particular issues when they occur? When using your logs for performance monitoring, here are some useful steps you can follow to dig a little deeper into any issues that you identify:

1. Set up real-time alerts

The first step is to get notified in real time when something important happens. For example, if you get an OutOfMemoryException (one of the common Tomcat errors we identified from our analysis), this can be pretty critical. You want to know right away so you can react appropriately. If an OutOfMemoryException was caused by a slow memory leak, often a server restart will buy you some time so you might even want to have your notifications configured with your infrastructure API to automatically restart an instance upon a given issue. Make sure your logging supports alerts that can be configured with third-party APIs and are sent in real time - i.e. seconds not minutes.

2. Understand what user behavior caused the issue

Once you know there is a particular problem in the system, the next set of steps are usually related to figuring out what caused it. Understanding how your system was being used at the time of, or leading up to, an issue can be a big help. This can help you localize the problem to a set of system components or functions. If your hunch is that a single user action can lead to a problem (e.g. you released a new UI feature that crashed when users started to play with it), session- or transaction-tracing techniques can really help here. Session or transaction tracing allows you to follow a user’s steps through your system in the order in which they were carried out such as the order in which they navigated your app interface or the steps they took before they added something to a shopping cart, for example.

Tracing in this way can be achieved by following some logging best practices, which suggest you should add the following details to your log events:

- A timestamp

- A unique user identifier (e.g. user name, user ID, email address)

- A unique session or transaction ID

Combining these three parameters allows you to retrace the steps of a user before an incident occurred.

If, on the other hand, the system issue was caused by group user behavior rather than a single user action, which is often the case with an OutOfMemoryException that featured as a common issue that surfaced in our research analysis, tracing a given transaction or session may not be sufficient to identify the root cause. Instead you might want to understand what were the most common system functions that all users have been carrying out. A great way to do this is to group log events by user actions to get a break down of what the most common user behavior is and how this breaks down over the past hour, day or week for example.

This will give you an immediate view of how your system is being used by groups of users and can help you nail down actions that may be resulting in leaking memory. Correlating increases in a given user action over the past 24 hours with increases in your heap size over that same time period can be a good way to point you in the right direction of a leak.

3. Check resource usage

Resource usage data can also be streamed into your log data such that it can be correlated with application exceptions or system errors.

When a given issue occurs in your system it may or may not be related to exhausted system resources such as CPU or memory. Typically issues like slow response time, timeouts or memory leaks can be related to resource usage. A quick look at your system resource usage when there is an issue is almost always a good idea and can help save you time when troubleshooting.

4. Determine if performance was affected

One of the first things you will need to communicate across your team when there is a system issue is: which users were effected and how it affected them. Another logging best practice worth following is to log important performance parameters from your application code, web servers and database queries. Request response time, response size and slow queries can be particularly useful to track. Combining this information with unique user identifiers (see #2) allows you to track performance at the per-user level such that you can see if individual users have been affected by a given system issue.

Furthermore, real user monitoring (RUM) using client-side logging libraries will allow you to capture log data from a client device (smart phone/tablet) apps or web browser. With RUM, you will not only capture the time spent in the system backend, but can also capture the perceived performance from the client’s perspective capturing total time it took before the response was received by the client. This can also capture delays in the network or with page loading times for example.

5. Identify what part of the application code caused the issue

Once you have established the exception type, the user behavior that led to the issue, resource usage at the time as well as how users were affected, you will want to immediately dive into the low-level details to figure out the issue in your code or the system process that caused the problem. Examining exception stack traces in your logs can help identify the culprit. For example, in the case of a UI bug, tracing a user transaction (as outlined in #2 above) will often capture the exception caused by a particular action. Digging into the exception stack trace can show you the exact method/object/function and line number where a bug was introduced.

When choosing your logging solution, make sure it can handle multi-line events, as exception traces are essentially single events that can span 10s or 100s of lines. With some solutions, it can be very frustrating when you search for an exception and do not get the full trace. Solutions that support multi-line events and show surrounding events around a given search can make life a lot easier when dealing with exception traces.

ABOUT Trevor Parsons

Trevor Parsons, PhD, is Co-founder and Chief Scientist of Logentries. Parsons is responsible for product strategy and direction. He works closely with customers and partners to continuously understand what they need, and to validate product market fit. Parsons also leads the product management and UX teams and assures the best possible user experience. Parsons enjoys speaking at local devops meet-ups and events, and is always looking for how log data and analytics can be applied in more and more powerful use cases. Parsons was a post doctoral researcher and member of the Performance Engineering Lab at the School of Computer Science and Informatics in University College Dublin, Ireland. He received a PhD from University College Dublin for his thesis titled Automatic Detection of Performance Design and Deployment Antipatterns in Component Based Enterprise Systems.

Share this

The Latest

November 12, 2019

We're in the middle of a technology and connectivity revolution, giving us access to infinite digital tools and technologies. Is this multitude of technology solutions empowering us to do our best work, or getting in our way? ...

November 07, 2019

Microservices have become the go-to architectural standard in modern distributed systems. While there are plenty of tools and techniques to architect, manage, and automate the deployment of such distributed systems, issues during troubleshooting still happen at the individual service level, thereby prolonging the time taken to resolve an outage ...

November 06, 2019

A recent APMdigest blog by Jean Tunis provided an excellent background on Application Performance Monitoring (APM) and what it does. A further topic that I wanted to touch on though is the need for good quality data. If you are to get the most out of your APM solution possible, you will need to feed it with the best quality data ...

November 05, 2019

Humans and manual processes can no longer keep pace with network innovation, evolution, complexity, and change. That's why we're hearing more about self-driving networks, self-healing networks, intent-based networking, and other concepts. These approaches collectively belong to a growing focus area called AIOps, which aims to apply automation, AI and ML to support modern network operations ...

November 04, 2019

IT outages happen to companies across the globe, regardless of location, annual revenue or size. Even the most mammoth companies are at risk of downtime. Increasingly over the past few years, high-profile IT outages — defined as when the services or systems a business provides suddenly become unavailable — have ended up splashed across national news headlines ...

October 31, 2019

APM tools are ideal for an application owner or a line of business owner to track the performance of their key applications. But these tools have broader applicability to different stakeholders in an organization. In this blog, we will review the teams and functional departments that can make use of an APM tool and how they could put it to work ...

October 30, 2019

Enterprises depending exclusively on legacy monitoring tools are falling behind in business agility and operational efficiency, according to a new study, Prevalence of Legacy Tools Paralyzes Enterprises' Ability to Innovate conducted by Forrester Consulting ...

October 29, 2019

Hyperconverged infrastructure is sometimes referred to as a "data center in a box" because, after the initial cabling and minimal networking configuration, it has all of the features and functionality of the traditional 3-2-1 virtualization architecture (except that single point of failure) ...

October 28, 2019

Hyperconvergence is a term that is gaining rapid interest across the manufacturing industry due to the undeniable benefits it has delivered to IT professionals seeking to modernize their data center, or as is a popular buzzword today ― "transform." Today, in particular, the manufacturing industry is looking to hyperconvergence for the potential benefits it can provide to its emerging and growing use of IoT and its growing need for edge computing systems ...

October 24, 2019

More than 92 percent of US respondents agree that Artificial Intelligence (AI) and Machine Learning (ML) will become important for how they run their digital systems ...