Have you experienced this scenario? A user reports a strange bug, but there’s no relevant information in the logs. You make an educated guess about the cause, add instrumentation points, wait for deployment, and analyze the data—only to discover your hypothesis was wrong. You add more instrumentation, deploy again… and this cycle repeats. A problem that could have been solved in minutes drags on for days.

In complex modern systems, the traditional ways—logs, instrumentation, and A/B testing—are increasingly inadequate. They can’t keep pace with rapid iteration cycles or address increasingly complex system architectures. Facing these challenges, a new technical solution is emerging—dynamic tracing.

Traditional Methods vs. Dynamic Tracing: A Revolution in Efficiency and Control

Imagine this scenario: the production environment suddenly experiences performance degradation, and user complaints flood in. Using traditional methods, you might need to:

1. Log Analysis: Sift through massive logs only to find critical information missing. While low-cost, logs provide fixed and limited information. They rely on developers’ predictive abilities—you can only see what you previously deemed important.

2. Adding Instrumentation: Modify code, deploy a new version, wait for data collection. Though offering more flexibility, this process is slow with long deployment cycles. Each adjustment requires going through the entire release process.

3. A/B Testing: More oriented toward behavior verification, often lacking the granularity to pinpoint specific technical issues.

4. Problem Reproduction: Attempting to reproduce issues in test environments, yet struggling to simulate real-world loads.

Fundamentally, these methods share a common weakness: you can only see what you correctly predicted would be important. But in reality, production environments always contain unexpected scenarios and edge cases.

Dynamic Tracing: X-Ray Vision for Your Systems

Dynamic tracing technology essentially provides you with eyes that can be opened at any time while the system is running. It consists of three components:

• Online Dynamic Instrumentation: Observe running programs without restarts by “drilling holes” into them
• Real-time Data Visualization: What you see is what you get, no waiting for data feedback
• Code Path Analysis: Understand actual program execution paths rather than making educated guesses

How does OpenResty XRay achieve “camera-like” visibility into system internals? Its core principle lies in non-intrusive probe technology. More importantly, dynamic tracing offers these key characteristics:

• Non-intrusive: No source code modification
• Hot-swappable: Enable or disable at any time
• Security Sandbox: Strict control over tracing code permissions
• Performance Control: Precise management of system performance impact

When you deploy an XRay probe, it “hooks” into specified function entry points, return points, or code paths without modifying the original code. Whenever these points are triggered, the probe collects contextual information—including call stacks, execution times, parameter values, etc.—and transmits this data to the analysis platform in real-time.

Notably, XRay probes are meticulously designed with minimal performance overhead. In our tests, even on high-load systems, the performance impact introduced by probes is typically very low—negligible in most scenarios.

From Flame Graphs to System Panorama

In OpenResty XRay, flame graphs serve as powerful and intuitive visualization tools for dynamically tracing the distribution of various system resources or performance metrics in target software. Through flame graphs, users can clearly see how CPU time, memory usage, disk I/O, latency, and other resources are specifically consumed across code paths.

For instance, in Lua-level performance analysis, XRay supports displaying filenames and specific line numbers in flame graphs, enabling developers to precisely locate specific lines of Lua source code, significantly improving debugging and optimization efficiency.

Behind all this is advanced dynamic tracing technology. Unlike traditional APM tools that may interfere with target processes through instrumentation or code injection, OpenResty XRay uses a non-intrusive sampling method. It requires no modifications to the target process and injects no code—even during sampling, the target process behaves almost identically to its unsampled state.

This lightweight, low-overhead approach ensures both the authenticity of collected data and the stability and security of the system. Consequently, OpenResty XRay flame graph analysis is suitable not only for development and testing environments but can also be safely applied to production systems to identify complex performance issues that are difficult to reproduce offline. Flame graphs are not just visualization tools but important gateways to a comprehensive view of system operations.

Why Choose OpenResty XRay?

There are several dynamic tracing tools on the market, such as DTrace, SystemTap, and bcc, but they all have significant limitations:

DTrace/SystemTap: High usage barriers, you need to learn specific scripting languages and understand kernel principles.

bcc: Though relatively modern, it’s still kernel-oriented and not sufficiently business-developer-friendly.

OpenResty XRay, however, is a dynamic tracing tool specifically designed for business developers:

• Business Developer-Oriented: No need to learn low-level languages; directly trace business logic
• Debug Symbol Database: Precise tracing even when source code is unavailable
• Ylang Language: C-like syntax supporting conditions, loops, and aggregations with minimal learning curve
• Cloud-based Unified Control: One person maintains, the entire team benefits, significantly lowering usage barriers

The Future of Observability: New Frontiers in Dynamic Tracing

Looking back at the evolution of observability technology: from initial Logs to Metrics monitoring, to Distributed Tracing, we are now entering the new era of Dynamic Tracing.

With the proliferation of edge computing, IoT devices, and AI inference services, system complexity is growing exponentially. Traditional observability methods can hardly cope with this complexity. Dynamic tracing technology, especially when combined with AIOps (AI Operations), will be key to addressing these challenges in the future.

OpenResty XRay’s long-term vision is to build a comprehensive observability platform where every behavior within a system can be observed, analyzed, and optimized. It will help engineers maintain control over systems in an increasingly complex technological landscape.

In debugging and optimizing complex systems, XRay transforms your approach from reactive to proactive, from hypothesis-testing to direct observation. It not only helps you solve problems faster but also helps you discover “unknown unknowns”—issues you didn’t even know existed.

In today’s world where performance is paramount and user experience is king, are you ready to embrace dynamic tracing technology and equip your system with “X-ray vision”? OpenResty XRay ensures your system internals are no longer black boxes and problem troubleshooting is no longer a guessing game.

What is OpenResty XRay

OpenResty XRay is a dynamic-tracing product that automatically analyzes your running applications to troubleshoot performance problems, behavioral issues, and security vulnerabilities with actionable suggestions. Under the hood, OpenResty XRay is powered by our Y language targeting various runtimes like Stap+, eBPF+, GDB, and ODB, depending on the contexts.

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About The Author

Yichun Zhang (Github handle: agentzh), is the original creator of the OpenResty^® open-source project and the CEO of OpenResty Inc..

Yichun is one of the earliest advocates and leaders of “open-source technology”. He worked at many internationally renowned tech companies, such as Cloudflare, Yahoo!. He is a pioneer of “edge computing”, “dynamic tracing” and “machine coding”, with over 22 years of programming and 16 years of open source experience. Yichun is well-known in the open-source space as the project leader of OpenResty^®, adopted by more than 40 million global website domains.

OpenResty Inc., the enterprise software start-up founded by Yichun in 2017, has customers from some of the biggest companies in the world. Its flagship product, OpenResty XRay, is a non-invasive profiling and troubleshooting tool that significantly enhances and utilizes dynamic tracing technology. And its OpenResty Edge product is a powerful distributed traffic management and private CDN software product.

As an avid open-source contributor, Yichun has contributed more than a million lines of code to numerous open-source projects, including Linux kernel, Nginx, LuaJIT, GDB, SystemTap, LLVM, Perl, etc. He has also authored more than 60 open-source software libraries.