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Application Performance Monitoring 101

A Complete Guide to What Is APM and How It Works

In today's digital market, modern apps have to not only bring value but provide around-the-clock availability, fast responses, and real-time problem-solving. Because all businesses rely on software applications their performance is one of every organization's main concerns and biggest headaches, especially if their applications are not just a part of their business, but the business itself. This is where APM comes into play.

In this guide, we are going to dive deep into what is application performance monitoring, how it works, and why and how to use it to help you troubleshoot performance issues faster and ensure peak app performance and flawless user experience.

Definition: What Is Application Performance Monitoring

Application Performance Monitoring (APM) is the strategy and practice of continuously monitoring and tracking application performance and availability, as well as end-user experience. Using APM solutions, IT and DevOps teams can detect anomalies, understand trends, optimize resource usage, and troubleshoot performance issues before they impact end users. Such tools enable you to gather insights that help ensure customer satisfaction and drive business growth.

Application Performance Monitoring shouldn't be confused with Application Performance Management as they are often used interchangeably as ‘APM.'

How Is Application Performance Management Different

Application Performance Management is the broader strategy of managing the overall performance, starting with code, application dependencies, transaction times, and user experience. Monitoring is a small – but critical – part of it. It points out, typically via alert notifications, that there is a problem.

On the other hand, performance management takes it a step further. By using the alerts sent out by your monitoring tool, it allows you to see when and where along their journey, users encountered problems and why these problems occurred. For example, monitoring will alert you that your app or website is slow or down, but management will help you understand the causes and make changes that could potentially address the problem.

Such a complete strategy ensures full visibility into app performance, helping DevOps teams spot trends and be better prepared to respond to similar issues in the future.

Why Do You Need Application Performance Monitoring

When it comes to the digital economy, avoiding downtime and measuring the availability, response time, and behavior of every business transaction is crucial.

Detect Why Applications Are Running Slow

When you're facing application slowness, you need to determine why your app is slow, since when it's been running slowly, and what is causing slowness. That would be easy if it were not for how modern software applications look today – highly distributed, multi-tier, multi-element architectures based on app development frameworks. However, while that helps build better software applications, it makes performance management and monitoring increasingly difficult if you were to stick to traditional monitoring techniques such as performing ping tests or measuring server-level metrics (network activity, memory, CPU, and disk usage, etc.).

These techniques can't help you analyze the interdependencies between components when you work with a distributed application. Logs, metrics, events are everywhere – in the cloud, across clouds, in hybrid clouds – sometimes hard to locate and manage, thus hard to find out why your app is running slow.

Ensure End-to-End Visibility of Your Application

There are other ways to work your way around application monitoring, with methods such as synthetic transactions, manual instrumentation of the code, or customer feedback. However, while these do have their own – important – role in a monitoring strategy, they need additional configuration until they can offer the same perks as an APM tool.

This would be both time- and money-consuming. Instead, a comprehensive APM solution gives you end-to-end visibility into how your application performs without needing extra effort from you.

How Does Application Performance Monitoring Work

Application performance monitoring works by:

  • Tracking if your app is behaving as it should, within normal parameters.
  • If not, sending alerts and collecting data regarding the source of the problem.
  • Analyzing the data while considering the impact it has on business.
  • Offering insight on how to adjust your app environment so that you can easily spot and fix similar issues in the future before they impact the end user. Thus, APM helps you take a proactive approach to troubleshooting.

What Does APM Measure: Metrics You Should Track

There are two types of metrics that APM tools measure: the ones that show how end-users experience app performance and those that monitor infrastructure resources. Below are the most critical application performance metrics you should monitor:

  • User satisfaction/Apdex scores – provided by Real User Monitoring (aka User Experience Monitoring), Apdex is a measurement of your users' level of satisfaction based on the response time of request(s) when interacting with your website or application.
  • Response time – the time it takes for a user of an application to receive a response from an application.
  • Error rates – the number of application errors in some period of time.
  • Number of application instances – the number of instances of some application. In today's dynamic deployments this number typically varies with traffic, application usage, etc.
  • Request rates – the number of requests in some period of time. The higher the rate, the busier the application.
  • Application and server, virtual machine, or container CPU usage – the CPU usage of the underlying infrastructure.
  • Application availability/uptime (SLAs) – the extent to which an application is operational, functional, and usable for fulfilling user requests.
  • Garbage Collection (GC) – for Java Virtual Machine, Node.js Virtual Machine, and other runtimes that perform garbage collection.

Application Performance Monitoring Strategy Requirements:

That sounds simple enough, but in reality, you need a non-trivial setup to reap the full benefits of application monitoring. Here's what your application performance monitoring strategy should include:

1. Digital Experience Monitoring

Also known as end-user experience monitoring (EUEM), digital experience monitoring (DEM) tracks how a software application behaves from a user's point of view, looking for the times when they experience slowness, downtime, or errors. You can monitor end user experience proactively with synthetic monitoring solutions like Sematext Synthetics, or passively with real-user monitoring, meaning tools such as Sematext Experience.

Learn about the difference between these two methods in our blog post about real user monitoring vs. synthetic monitoring and see where RUM fits into the APM strategy in RUM vs. APM.

2. Dynamic Application Architecture Display (Service Map)

This is a map of how all the components of your application communicate with each other. APM tools automatically discover these dependencies and interactions and update them in real-time. Having the data available in a visual form makes problem detection easier.

3. Code Profiling

Transaction profiling, also known as transaction tracing or code-level performance profiling, analyzes the flow of every user transaction and isolates specific interactions where performance issues are detected. Tracing allows you to follow the user's journey from frontend to backend. That way, you can find the exact line of code, database query, or third-party call that affects application performance.

4. Transaction Tracing

Many performance issues are caused by memory leaks in the server, slow network connectivity, virtualization bottlenecks, etc., making infrastructure monitoring a must for ensuring peak app performance.

An application performance monitoring tool enables deep-dive analysis by collecting performance metrics in the form of transaction traces from all the components in your infrastructure. More specifically, it performs distributed transaction tracing, as it tracks transactions across tier boundaries providing end-to-end performance visibility along with the information you need (app and server metrics) to connect application infrastructure and performance with the user journey. Such solutions help keep an eye on the health of every business transaction as they happen so that you can easily understand when, where and why app slowness happened and user experience was affected.

5. IT Operations Analytics

IT operations analytics refers to analyzing data to identify usage patterns, trends, and performance issues that you can leverage to build a better plan on how to deal with similar situations before they occur and affect end-users.

Application Performance Monitoring Tools

A complete application monitoring solution consists of one or more tools that allow you to monitor all three core elements we mentioned earlier – digital experience monitoring, application discovery, tracing and diagnostics, and artificial intelligence for IT operations.

Unfortunately, there are no free open-source projects that cover all three aspects of APM as a package. Usually, they offer only one, be it infrastructure monitoring, RUM, or tracing, which you can combine if you want to go open-source all the way. Among the best, we can name Jaeger, Zipkin, Stagemonitor, Pinpoint, Weave Scope, Scouter, and Apache Skywalking. They've gathered large communities around them that are driven to innovate and help by coming with new features that meet users' needs.

On the other hand, there are a lot of vendors that offer both standalone monitoring tools and the whole package. We, at Sematext, are one of them.

Why Use Sematext as an APM Tool

Sematext Cloud is an APM solution. It provides end-to-end visibility into your web application's performance. It traces requests across multiple applications, tiers, servers, microservices, and processes, all the way down to databases, to detect the slowest and under-performing parts of your stack.

Sematext uses this data along with error rates and failed transactions to build a dynamic map of your complete app architecture – including connections to external services and databases – that shows how all components interact with each other. The AppMap makes it easier for you to track application health and performance.

How to Choose the Right APM Software

Besides being easy to use and able to provide actionable insights, your application performance monitoring tools should be able to:

  • manage applications in language(s) your applications use
  • monitor performance at code-level
  • track end-user experience
  • use artificial intelligence
  • allow you to monitor the entire infrastructure
  • offer information that helps you connect app performance metrics with business outcomes.


As businesses go through digital transformations such as cloud migration and container orchestration the risk of app downtime goes up, making application performance management and monitoring more important than ever.

APM is essential to ensure software application availability, making using such a tool a must, especially if you're running a SaaS business. APM tools help DevOps understand how application releases affect service performance, security, and reliability. They enable teams to set up alerts to detect and solve issues before they impact user experience and set up automated actions based on specific events, patterns, and trends.

Hopefully, this tutorial helped you understand better what APM means, why you need it as part of your monitoring and alerting strategy, and how to use it to deliver enhanced app performance, improved digital user experience, and, ultimately, to drive business growth.

Now all you have to do is pick the right APM tool and you're good to go!