Featured Articles

Photo by Yichun Zhang
dynamic-tracing
...
openresty-xray bilibili
8 mins read

How a Single "0" Took Down Bilibili — Every Server at 100% CPU, and Reboots Didn't Help

How a Single "0" Took Down Bilibili — Every Server at 100% CPU, and Reboots Didn't Help

Binary Vulnerability Scanning: Catch Backported Patches, Cut False Positives
security
...
vulnerability openresty-xray cve
10 mins read

Binary Vulnerability Scanning: Catch Backported Patches, Cut False Positives

Binary Vulnerability Scanning: Catch Backported Patches, Cut False Positives

Introduction to OpenResty XRay
openresty-xray
...
nginx
6 mins read

Introduction to OpenResty XRay

Introduction to OpenResty XRay

Nginx Reverse Proxy QPS Dropped 15x: A Missing upstream keepalive and an -O0 Debug Build
openresty-xray
...
case-study lua nginx off-cpu
4 mins read

Nginx Reverse Proxy QPS Dropped 15x: A Missing upstream keepalive and an -O0 Debug Build

Nginx Reverse Proxy QPS Dropped 15x: A Missing upstream keepalive and an -O0 Debug Build

Non-Invasive Java Profiler: Capture Method Arguments in Production Without a Java Agent
openresty-xray
...
java probe
4 mins read

Non-Invasive Java Profiler: Capture Method Arguments in Production Without a Java Agent

Non-Invasive Java Profiler: Capture Method Arguments in Production Without a Java Agent

Photo by Philip Brown
dynamic-tracing
...
openresty-xray
26 mins read

The Wonderland of Dynamic Tracing (Part 1 of 3)

The Wonderland of Dynamic Tracing (Part 1 of 3)

Photo by Jose G. Ortega Castro
nginx
...
openresty memory openresty-xray dynamic-tracing
13 mins read

How OpenResty and Nginx Shared Memory Zones Consume RAM

How OpenResty and Nginx Shared Memory Zones Consume RAM

Photo by Harrison Broadbent
nginx
...
openresty memory luajit openresty-xray dynamic-tracing
13 mins read

Nginx Memory Usage Explained: Where the RAM Actually Goes

Nginx Memory Usage Explained: Where the RAM Actually Goes

OpenResty XRay reduce your CPU usage up to  90%
OpenResty XRay reduce your CPU usage up to 90%
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Latest Articles

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 3 mins read

Performance Impact of OpenResty XRay when Tracing PHP Apps

tutorial openresty-xray php overhead
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Tested in Production: The Performance Impact of OpenResty XRay When Tracing Rust Applications

tutorial openresty-xray rust overhead
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 4 mins read

Dynamic-Tracing Custom Go Programs with Custom Ylang Analyzers (using OpenResty XRay)

tutorial openresty-xray ylang analyzer go
  • Insert two key-value Pairs into a Go Variable
  • Write a Customize Ylang Analyzer to Dynamically Trace the Go program
  • Test the Results
  • What is OpenResty XRay
  • Insert two key-value Pairs into a Go Variable
  • Write a Customize Ylang Analyzer to Dynamically Trace the Go program
  • Test the Results
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Django Memory Profiler: Analyze Object-Level Memory Usage in a Live App

tutorial openresty-xray python memory django
  • Spot a high-memory Django process with ps
  • Profile the Django app’s memory usage with Guided Analysis
  • Read the flame graph: which Python module uses the most memory
  • Monitor Django memory usage automatically with Insights
  • What is OpenResty XRay
  • Spot a high-memory Django process with ps
  • Profile the Django app’s memory usage with Guided Analysis
  • Read the flame graph: which Python module uses the most memory
  • Monitor Django memory usage automatically with Insights
  • What is OpenResty XRay

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 4 mins read

Install OpenResty XRay’s Agents on CentOS via RPM Packages

tutorial openresty-xray centos agent install
  • Logging in to the Console
  • Installing the Agent via RPM Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay
  • Logging in to the Console
  • Installing the Agent via RPM Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Python Memory Profiler: Find the Largest Objects Eating RAM Without Code Changes

tutorial openresty-xray python memory
  • Find which Python process is using the most memory
  • Profile Python memory with guided analysis: find the largest objects and their modules
  • Automatically monitor Python memory usage with scheduled reports
  • What is OpenResty XRay
  • Find which Python process is using the most memory
  • Profile Python memory with guided analysis: find the largest objects and their modules
  • Automatically monitor Python memory usage with scheduled reports
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

Rust CPU Profiling: Find the Hottest Code Paths in Sled with OpenResty XRay

tutorial openresty-xray cpu sled rust profiling flame-graph
  • The problem: a Sled-based cache service using over 100% CPU
  • Profile the running Rust process with Guided Analysis
  • Read the Rust CPU flame graph: the #1 hottest code path
  • The #2 hottest code path: get_inner and view_for_key
  • Automatic Rust CPU analysis reports
  • Frequently asked questions
  • The problem: a Sled-based cache service using over 100% CPU
  • Profile the running Rust process with Guided Analysis
  • Read the Rust CPU flame graph: the #1 hottest code path
  • The #2 hottest code path: get_inner and view_for_key
  • Automatic Rust CPU analysis reports
  • Frequently asked questions

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

etcd High CPU Usage: Find the Hottest Go Code Paths with Flame Graphs

tutorial openresty-xray go cpu etcd
  • Symptom: etcd consuming over 70% of a CPU core
  • Use OpenResty XRay Guided Analysis to find the hottest Go code paths
  • Automatic etcd CPU monitoring and reports
  • What is OpenResty XRay
  • Symptom: etcd consuming over 70% of a CPU core
  • Use OpenResty XRay Guided Analysis to find the hottest Go code paths
  • Automatic etcd CPU monitoring and reports
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

llama.cpp CPU Usage: 400% CPU Traced to ggml Hot Functions

tutorial openresty-xray llm cpu generative-ai llama2 llama.cpp profiling ai
  • Running llama.cpp and Observing 400% CPU Usage
  • Profiling llama.cpp CPU Usage with OpenResty XRay
  • Findings: The Hottest C++ Code Paths
  • What is OpenResty XRay
  • Running llama.cpp and Observing 400% CPU Usage
  • Profiling llama.cpp CPU Usage with OpenResty XRay
  • Findings: The Hottest C++ Code Paths
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Go Off-CPU Analysis: Tracing a Running Process Stuck at 2% CPU to a Blocking Shell Call

tutorial openresty-xray go cpu
  • The symptom: Go service CPU usage stays low under load
  • Running off-CPU analysis on the live Go process with OpenResty XRay
  • Root cause: a blocking shell command at a single source line
  • Automatic analysis and reports
  • The symptom: Go service CPU usage stays low under load
  • Running off-CPU analysis on the live Go process with OpenResty XRay
  • Root cause: a blocking shell command at a single source line
  • Automatic analysis and reports

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Python Process Stuck at 8% CPU: Off-CPU Analysis Traces a Blocking subprocess.run Call

tutorial openresty-xray python off-cpu
  • The symptom: Python process CPU usage stays low under heavy requests
  • Find the blocking Python code paths with OpenResty XRay’s Guided Analysis
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author
  • The symptom: Python process CPU usage stays low under heavy requests
  • Find the blocking Python code paths with OpenResty XRay’s Guided Analysis
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Lua High CPU Usage: Find the Hottest Lua Code Path in Nginx/OpenResty

tutorial openresty-xray lua cpu flame-graph profiling
  • The symptom: an Nginx worker process using almost 100% CPU
  • Find the hottest Lua code path with Guided Analysis
  • Monitor Lua CPU usage automatically with Insights reports
  • Frequently asked questions
  • The symptom: an Nginx worker process using almost 100% CPU
  • Find the hottest Lua code path with Guided Analysis
  • Monitor Lua CPU usage automatically with Insights reports
  • Frequently asked questions

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 6 mins read

Kong Plugin High CPU Usage: A Hidden Lua Exception Traced with Flame Graphs

openresty-xray exceptions lua kong nginx cpu
  • The problem: Kong plugin high CPU usage under light traffic
  • Finding the CPU bottleneck with an OpenResty XRay flame graph
  • The result: Kong CPU usage cut from 80% to 50%
Photo by Yichun Zhang
  • The problem: Kong plugin high CPU usage under light traffic
  • Finding the CPU bottleneck with an OpenResty XRay flame graph
  • The result: Kong CPU usage cut from 80% to 50%

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 8 mins read

Find Leaked Lua Tables: the registry / _LOADED (package.loaded) Reference Path in OpenResty XRay

openresty memory-leak openresty-xray case-study
  • How LuaJIT manages memory
  • OpenResty XRay’s command-line tools
  • A leaking Lua table example
  • Breaking down memory by LuaJIT GC object type
  • Reading the lj-gco-ref flame graph: registry, _LOADED, package.loaded
  • Fully-automated Lua memory leak analysis
  • How LuaJIT manages memory
  • OpenResty XRay’s command-line tools
  • A leaking Lua table example
  • Breaking down memory by LuaJIT GC object type
  • Reading the lj-gco-ref flame graph: registry, _LOADED, package.loaded
  • Fully-automated Lua memory leak analysis

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 17 mins read

Flame Graphs: How to Read a CPU Flame Graph and Find the Code Burning Your CPU

tutorial flame-graph cpu profiling openresty-xray performance
  • What is a flame graph: definition, axes, and the four rules
  • How to read a flame graph: plateaus, towers, hair, and self vs total
  • Three real production flame graphs: PHP preg_match, Go regexp.MustCompile, Erlang erts_pcre_exec
  • From 100% CPU to the culprit line: a four-step workflow with a per-stack routing table
  • How to get a flame graph for your stack
  • Icicle graphs, flame charts, and other variants
  • Can AI read flame graphs for you?
  • What is a flame graph: definition, axes, and the four rules
  • How to read a flame graph: plateaus, towers, hair, and self vs total
  • Three real production flame graphs: PHP preg_match, Go regexp.MustCompile, Erlang erts_pcre_exec
  • From 100% CPU to the culprit line: a four-step workflow with a per-stack routing table
  • How to get a flame graph for your stack
  • Icicle graphs, flame charts, and other variants
  • Can AI read flame graphs for you?

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 17 mins read

P99 Latency: Why Averages Lie, and How to Diagnose the Slowest 1%

openresty-xray p99 latency performance flame-graph
  • What is P99 latency?
  • P50 vs P95 vs P99: what each percentile tells you
  • Why average latency lies
  • Why is P99 latency high? A root-cause spectrum
  • How to diagnose high P99 latency
  • How to reduce P99 latency: fix what you found
  • Summary
  • Frequently Asked Questions
  • What is P99 latency?
  • P50 vs P95 vs P99: what each percentile tells you
  • Why average latency lies
  • Why is P99 latency high? A root-cause spectrum
  • How to diagnose high P99 latency
  • How to reduce P99 latency: fix what you found
  • Summary
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 14 mins read

Memory Leak Detection in Production: From RSS Curve to Source Line

openresty-xray memory tutorial
  • The Symptom: A Memory Curve That Only Goes Up
  • Memory Leak or Just High Memory Usage?
  • Four Leak Patterns with Real Root-Cause Chains
  • It Looks Like a Leak, but It Isn’t
  • How to Locate a Leak: Top-Down Layered Attribution
  • Why Traditional Tools Fall Short in Production
  • Frequently Asked Questions
  • The Symptom: A Memory Curve That Only Goes Up
  • Memory Leak or Just High Memory Usage?
  • Four Leak Patterns with Real Root-Cause Chains
  • It Looks Like a Leak, but It Isn’t
  • How to Locate a Leak: Top-Down Layered Attribution
  • Why Traditional Tools Fall Short in Production
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 11 mins read

Off-CPU Analysis: Four Root Causes Behind Low CPU Yet High Latency

openresty-xray off-cpu tutorial
  • What Is Off-CPU Time?
  • The Symptom: CPU Usage Won’t Climb, Yet Requests Are Queuing
  • Four Categories of Off-CPU Root Causes with Real-World Root-Cause Chains
  • How to Quantify Off-CPU Time
  • On-CPU + Off-CPU = Wall-Clock Time: The Bigger Picture and the Tool Ecosystem
  • FAQ
  • What Is Off-CPU Time?
  • The Symptom: CPU Usage Won’t Climb, Yet Requests Are Queuing
  • Four Categories of Off-CPU Root Causes with Real-World Root-Cause Chains
  • How to Quantify Off-CPU Time
  • On-CPU + Off-CPU = Wall-Clock Time: The Bigger Picture and the Tool Ecosystem
  • FAQ

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 13 mins read

How OpenResty XRay Enables Full-Stack Dynamic Tracing in Production

openresty-xray ylang dynamic-tracing
  • Where Do Existing Dynamic Tracing Frameworks Fall Short in Production?
  • How Did OpenResty XRay Rethink Dynamic Tracing at the Architecture Level?
  • What Is a Full-Stack Flame Graph and How Do You Use It to Diagnose Performance Bottlenecks?
  • How Is OpenResty XRay Expanding Its Observability Coverage Over Time?
  • Further Reading and Real-World Case Studie
  • Where Do Existing Dynamic Tracing Frameworks Fall Short in Production?
  • How Did OpenResty XRay Rethink Dynamic Tracing at the Architecture Level?
  • What Is a Full-Stack Flame Graph and How Do You Use It to Diagnose Performance Bottlenecks?
  • How Is OpenResty XRay Expanding Its Observability Coverage Over Time?
  • Further Reading and Real-World Case Studie

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Introduction to OpenResty XRay

openresty-xray nginx
  • Core Philosophy: A Tracing Engine Built for the Unknown
  • Turning Noise into Signal: How XRay Demystifies Production Issues
  • Empowering Engineering Teams in Cloud-Native Reality
  • Built on a Robust, Open Technological Foundatione
  • Real-World Success Stories
  • Core Philosophy: A Tracing Engine Built for the Unknown
  • Turning Noise into Signal: How XRay Demystifies Production Issues
  • Empowering Engineering Teams in Cloud-Native Reality
  • Built on a Robust, Open Technological Foundatione
  • Real-World Success Stories

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 4 mins read

Nginx Reverse Proxy QPS Dropped 15x: A Missing upstream keepalive and an -O0 Debug Build

openresty-xray case-study lua nginx off-cpu
  • A 15x Slower Nginx Reverse Proxy — and No Errors in the Logs
  • Flame Graphs Expose a Connection Storm: The Missing upstream keepalive
  • The Remaining 10% Gap: Baseline Comparison Points to the Compiler
  • How an -O0 Debug Build Cost Us 10% of Performance
  • A 15x Slower Nginx Reverse Proxy — and No Errors in the Logs
  • Flame Graphs Expose a Connection Storm: The Missing upstream keepalive
  • The Remaining 10% Gap: Baseline Comparison Points to the Compiler
  • How an -O0 Debug Build Cost Us 10% of Performance

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 9 mins read

How We Pinpointed a 244ms Latency Spike in a 500k QPS OpenResty Gateway

openresty-xray qps p99 cpu
  • Latency Spikes and CPU Waste Hidden Beneath Healthy Averages
  • Troubleshooting OpenResty Latency Without Code Changes or Restarts
  • The Results: Latency Spikes Eliminated, 30% Lower CPU Usage
  • Frequently Asked Questions
  • Latency Spikes and CPU Waste Hidden Beneath Healthy Averages
  • Troubleshooting OpenResty Latency Without Code Changes or Restarts
  • The Results: Latency Spikes Eliminated, 30% Lower CPU Usage
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 11 mins read

How to Diagnose Java Memory Leaks in Production — Without Heap Dumps or Restarts

openresty-xray java memory
  • Why Full GCs Didn’t Reclaim the Heap: A Production Java Memory Leak
  • How to Diagnose a Java Memory Leak in Production Without a Heap Dump
  • How to Find a Java Memory Leak: A Reusable 3-Step Method
  • Why Use OpenResty XRay to Find Java Memory Leaks on a Live JVM?
  • FAQ
  • Why Full GCs Didn’t Reclaim the Heap: A Production Java Memory Leak
  • How to Diagnose a Java Memory Leak in Production Without a Heap Dump
  • How to Find a Java Memory Leak: A Reusable 3-Step Method
  • Why Use OpenResty XRay to Find Java Memory Leaks on a Live JVM?
  • FAQ

OpenResty XRay Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 2 mins read

OpenResty XRay Version 25.10.11 Now Available

openresty-xray releases
  • Three Key Highlights
  • Enhanced Diagnostic Accuracy and Stability
  • Usability and Security Enhancements
  • Three Key Highlights
  • Enhanced Diagnostic Accuracy and Stability
  • Usability and Security Enhancements

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 9 mins read

Gzip CPU Usage: Why Compression Level 6 Consumed 54% of Server CPU

case-study openresty-xray gzip cpu
  • How Gzip Compression Consumed 54% of CPU in Production
  • Why Gzip CPU Usage Was So High: A Configuration-Level Diagnosis
  • Quantifying Gzip and Brotli CPU Overhead
  • From Guesswork to Data-Driven Compression Tuning
  • How Gzip Compression Consumed 54% of CPU in Production
  • Why Gzip CPU Usage Was So High: A Configuration-Level Diagnosis
  • Quantifying Gzip and Brotli CPU Overhead
  • From Guesswork to Data-Driven Compression Tuning

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 4 mins read

Nginx C++ Module Memory Leak: Root Cause in Production, No Restart

case-study openresty-xray nginx c++
  • The Production Challenge: A C++ Module Memory Leak You Can’t Debug With GDB
  • How the Flame Graph Pinpointed the Leaking Function in ngx_dubbo_module
  • From Reactive to Proactive: XRay’s New Approach to Troubleshooting
  • The OpenResty XRay Closed-Loop Approach
  • The Production Challenge: A C++ Module Memory Leak You Can’t Debug With GDB
  • How the Flame Graph Pinpointed the Leaking Function in ngx_dubbo_module
  • From Reactive to Proactive: XRay’s New Approach to Troubleshooting
  • The OpenResty XRay Closed-Loop Approach

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 4 mins read

Non-Invasive Java Profiler: Capture Method Arguments in Production Without a Java Agent

openresty-xray java probe
  • Why Non-Invasive Java Profiling Matters in Production
  • Hands-on Demo: Capturing Java Method Arguments in Production
  • How OpenResty XRay Differs from Common Java Profilers
  • Frequently Asked Questions
  • Why Non-Invasive Java Profiling Matters in Production
  • Hands-on Demo: Capturing Java Method Arguments in Production
  • How OpenResty XRay Differs from Common Java Profilers
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Automated Root Cause Analysis: How OpenResty XRay Pinpoints Failures Down to the Code Line

openresty-xray dynamic-tracing analyzer
  • Why More Observability Data Doesn’t Mean Faster Root Cause Analysis
  • How XRay’s Automated Root Cause Analysis Differs from Traditional Monitoring
  • Automated Root Cause Analysis in Action: Three Production Cases
  • FAQ
  • Why More Observability Data Doesn’t Mean Faster Root Cause Analysis
  • How XRay’s Automated Root Cause Analysis Differs from Traditional Monitoring
  • Automated Root Cause Analysis in Action: Three Production Cases
  • FAQ

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 10 mins read

Node.js Function Probe: Capture Live Function Arguments Without Changing Code

openresty-xray node.js
  • Why Trace Node.js Functions Without Modifying Code
  • How to Capture Node.js Function Arguments Without Modifying Code
  • How Teams Use Non-Invasive Node.js Probes in Production
  • Why Trace Node.js Functions Without Modifying Code
  • How to Capture Node.js Function Arguments Without Modifying Code
  • How Teams Use Non-Invasive Node.js Probes in Production

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 9 mins read

The Nginx Worker That Refused to Serve More Than 300 RPS: Traced to a 75ms Event-Loop Block

openresty-xray case-study lua nginx off-cpu
  • High Load but No Useful Work: CPU Contention from a Missing worker_cpu_affinity
  • How Blocking Lua I/O Calls Halted the Nginx Event Loop
  • Measuring File I/O Latency: Up to 1.5ms per Call
  • How Bad Was the Nginx Event-Loop Blocking? 43,952 Samples, a 75ms Worst Case
  • Frequently Asked Questions
  • High Load but No Useful Work: CPU Contention from a Missing worker_cpu_affinity
  • How Blocking Lua I/O Calls Halted the Nginx Event Loop
  • Measuring File I/O Latency: Up to 1.5ms per Call
  • How Bad Was the Nginx Event-Loop Blocking? 43,952 Samples, a 75ms Worst Case
  • Frequently Asked Questions

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 10 mins read

Non-Invasive Node.js CPU Profiling with Flame Graphs

openresty-xray node.js memory cpu
  • High CPU Usage Issues in Node.js Applications
  • CPU Blocking Issues in Node.js Applications
  • Automated Sampling and Expert Analysis
  • Performance Impact and Overhead
  • Future Plans
  • High CPU Usage Issues in Node.js Applications
  • CPU Blocking Issues in Node.js Applications
  • Automated Sampling and Expert Analysis
  • Performance Impact and Overhead
  • Future Plans

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 11 mins read

Nginx Core Dump Analysis: Catch a Worker Process Crash at the First Scene

case-study openresty-xray undo core-dump memory nginx
  • The Case: Frequent Nginx Worker Process Crashes No Log Could Explain
  • Analyzing the Recording: Replaying the Crash Back to the First Scene
  • Root Cause: A Use-After-Free in Nginx’s Connection Lifecycle
  • Frequently Asked Questions
  • The Case: Frequent Nginx Worker Process Crashes No Log Could Explain
  • Analyzing the Recording: Replaying the Crash Back to the First Scene
  • Root Cause: A Use-After-Free in Nginx’s Connection Lifecycle
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 9 mins read

UDB + OpenResty XRay: Unlocking the Mystery of OpenResty Application Performance

openresty-xray undo lua udb
  • How OpenResty XRay Enhances Efficiency with UDB
  • Hands-On: Analyzing OpenResty Lua Call Stacks with UDB and OpenResty XRay
  • Advantages of Time-Travel Debugging
  • Summary
  • How OpenResty XRay Enhances Efficiency with UDB
  • Hands-On: Analyzing OpenResty Lua Call Stacks with UDB and OpenResty XRay
  • Advantages of Time-Travel Debugging
  • Summary

OpenResty XRay Jul 23, 2026

OpenResty XRay Updated Jul 23, 2026 8 mins read

How to Debug File I/O in Java with Time-Travel Call Stacks

openresty-xray undo java udb
  • Where IDE Breakpoints and Coredumps Fall Short in Java File I/O
  • Reconstructing the Full Java Call Stack from a Native write() Syscall
  • Debug Java File I/O Step by Step with Time-Travel Replay
  • Frequently Asked Questions
  • Where IDE Breakpoints and Coredumps Fall Short in Java File I/O
  • Reconstructing the Full Java Call Stack from a Native write() Syscall
  • Debug Java File I/O Step by Step with Time-Travel Replay
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 4 mins read

Unveiling Python Code Execution with UDB

openresty-xray undo python udb
  • The Unique Value of UDB in Python Debugging
  • Enhancing Debugging Capabilities with OpenResty XRay
  • Real-World Example: Analyzing Python Network Request Call Stacks
  • Summary
  • The Unique Value of UDB in Python Debugging
  • Enhancing Debugging Capabilities with OpenResty XRay
  • Real-World Example: Analyzing Python Network Request Call Stacks
  • Summary

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

Tracing an LRU Cache Memory Leak in OpenResty — Down to the Cached SSL Certificates

case-study openresty-xray lru memory
  • Why a Low-Traffic OpenResty App Kept Leaking Memory
  • How We Traced the LRU Cache Memory Leak, Step by Step
  • The Result: From Unbounded Growth to Stable Memory
  • Why a Low-Traffic OpenResty App Kept Leaking Memory
  • How We Traced the LRU Cache Memory Leak, Step by Step
  • The Result: From Unbounded Growth to Stable Memory

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Uneven Nginx Worker CPU Usage: Tracing a Missing reuseport Flag and a cjson Hotspot

tutorial openresty-xray customer-story case-study
  • The Symptom: Some Nginx Workers Maxed Out While Others Sat Idle
  • How OpenResty XRay Pinpointed the Root Causes
  • The Fix: Three Optimizations and Their Measured Gains
  • Summary: What OpenResty XRay Found in Minutes
  • Frequently Asked Questions
  • What is OpenResty XRay
  • The Symptom: Some Nginx Workers Maxed Out While Others Sat Idle
  • How OpenResty XRay Pinpointed the Root Causes
  • The Fix: Three Optimizations and Their Measured Gains
  • Summary: What OpenResty XRay Found in Minutes
  • Frequently Asked Questions
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 9 mins read

The Swiss Army Knife for Dynamic Tracing, How Ylang Tames Complexity

tutorial openresty-xray ylang dynamic-tracing
  • Industry Pain Point: Why We Desperately Need a New Tracing Language
  • The Core Tech: What Makes Y Language a Game-Changer?
  • Ylang Syntax: The Familiarity of C, The Power of Advanced Tracing
  • Killer Applications: Solving Problems Beyond the Reach of Traditional Tools
  • Universal Platform Support: Y Lang Goes Everywhere
  • Compiler Wizardry: Forging a Superior Language with Superior Tools
  • Industry Pain Point: Why We Desperately Need a New Tracing Language
  • The Core Tech: What Makes Y Language a Game-Changer?
  • Ylang Syntax: The Familiarity of C, The Power of Advanced Tracing
  • Killer Applications: Solving Problems Beyond the Reach of Traditional Tools
  • Universal Platform Support: Y Lang Goes Everywhere
  • Compiler Wizardry: Forging a Superior Language with Superior Tools

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 10 mins read

Why Dynamic Tracing is the Future of Production Troubleshooting

tutorial openresty-xray ylang dynamic-tracing
  • The Unseen Crisis in Modern Software
  • Why Traditional Tools Are Failing
  • Dynamic Tracing: The New Paradigm for Troubleshooting
  • The OpenResty XRay Difference
  • From Firefighting to True Observability
  • The Unseen Crisis in Modern Software
  • Why Traditional Tools Are Failing
  • Dynamic Tracing: The New Paradigm for Troubleshooting
  • The OpenResty XRay Difference
  • From Firefighting to True Observability

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 9 mins read

Deep Dive into Dynamic Tracing Technology: How OpenResty XRay Revolutionizes Problem Diagnosis

tutorial openresty-xray ylang dynamic-tracing
  • Dynamic Tracing: A Powerful Tool for Solving Complex System Issues
  • Why Choose OpenResty XRay?
  • Product Focus: XRay Applications in Real-World Scenarios
  • Common Misconceptions and FAQs: What You Might Want to Know About Dynamic Tracing
  • Dynamic Tracing: A Powerful Tool for Solving Complex System Issues
  • Why Choose OpenResty XRay?
  • Product Focus: XRay Applications in Real-World Scenarios
  • Common Misconceptions and FAQs: What You Might Want to Know About Dynamic Tracing

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 7 mins read

The Next Stop for Observability: How OpenResty XRay Redefines Problem Troubleshooting

tutorial openresty-xray ylang dynamic-tracing
  • Why is Problem Troubleshooting Becoming Increasingly Difficult in Modern Software Architecture?
  • Trend Insights: The Future of Observability Technology
  • How Does Dynamic Tracing Technology Break Through Abstraction Layers?
  • Use Case: Real-time Statistics of Plugin Resource Consumption in Production Kong Services
  • Conclusion
  • Why is Problem Troubleshooting Becoming Increasingly Difficult in Modern Software Architecture?
  • Trend Insights: The Future of Observability Technology
  • How Does Dynamic Tracing Technology Break Through Abstraction Layers?
  • Use Case: Real-time Statistics of Plugin Resource Consumption in Production Kong Services
  • Conclusion

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 7 mins read

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

tutorial openresty-xray ylang dynamic-tracing
  • A Revolution in Efficiency and Control
  • Dynamic Tracing: X-Ray Vision for Your Systems
  • From Flame Graphs to System Panorama
  • Why Choose OpenResty XRay?
  • The Future of Observability: New Frontiers in Dynamic Tracing
  • A Revolution in Efficiency and Control
  • Dynamic Tracing: X-Ray Vision for Your Systems
  • From Flame Graphs to System Panorama
  • Why Choose OpenResty XRay?
  • The Future of Observability: New Frontiers in Dynamic Tracing

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 9 mins read

Why is Dynamic Tracing Difficult to Implement? How Does OpenResty XRay Break Through?

tutorial openresty-xray ylang dynamic-tracing
  • Why is Problem Troubleshooting Becoming Increasingly Difficult in Modern Software Architecture?
  • Trend Insights: The Future of Observability Technology
  • How Does Dynamic Tracing Technology Break Through Abstraction Layers?
  • Use Case: Real-time Statistics of Plugin Resource Consumption in Production Kong Services
  • Conclusion
  • Why is Problem Troubleshooting Becoming Increasingly Difficult in Modern Software Architecture?
  • Trend Insights: The Future of Observability Technology
  • How Does Dynamic Tracing Technology Break Through Abstraction Layers?
  • Use Case: Real-time Statistics of Plugin Resource Consumption in Production Kong Services
  • Conclusion

OpenResty XRay Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 5 mins read

Self-Optimization: The Performance Evolution of OpenResty XRay

tutorial openresty-xray
  • Challenges and Pain Points
  • OpenResty XRay’s Self-Analysis Process
  • Remarkable Optimization Results
  • Technical Insights and Business Value
  • Conclusion
  • Challenges and Pain Points
  • OpenResty XRay’s Self-Analysis Process
  • Remarkable Optimization Results
  • Technical Insights and Business Value
  • Conclusion

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 4 mins read

Case Study: OpenResty XRay Doubles Ylang Compiler Performance

tutorial ylang openresty-xray analyzer
  • Case Study: OpenResty XRay Doubles Ylang Compiler Performance
  • Significant Optimization Results
  • Ylang Language: The Ideal Tool for Dynamic Tracing
  • A Model of Technical Synergy
  • Further Reading
  • Case Study: OpenResty XRay Doubles Ylang Compiler Performance
  • Significant Optimization Results
  • Ylang Language: The Ideal Tool for Dynamic Tracing
  • A Model of Technical Synergy
  • Further Reading

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 10 mins read

Java Application Profiling: CPU, Off-CPU & Disk I/O Without Safepoint Bias

openresty-xray java memory cpu
  • Profiling Java CPU hotspots with flame graphs
  • Off-CPU Java profiling: lock contention and blocking analysis
  • Java disk I/O profiling: tracing file and socket writes
  • OpenJDK 8/11/17/21 application profiling support
  • Automated sampling and expert analysis
  • Performance impact and overhead
  • FAQ
Photo by Yichun Zhang
  • Profiling Java CPU hotspots with flame graphs
  • Off-CPU Java profiling: lock contention and blocking analysis
  • Java disk I/O profiling: tracing file and socket writes
  • OpenJDK 8/11/17/21 application profiling support
  • Automated sampling and expert analysis
  • Performance impact and overhead
  • FAQ

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

OpenResty XRay Mobile Apps: Monitor and Troubleshoot Your Apps from Android & iOS

tutorial openresty-xray mobile app
  • Download and install OpenResty XRay for Android
  • Sign into OpenResty XRay
  • Automatic analysis report
  • View the performance chart data on the dashboard page
  • Guided analysis feature
  • Frequently asked questions
  • What is OpenResty XRay
  • Download and install OpenResty XRay for Android
  • Sign into OpenResty XRay
  • Automatic analysis report
  • View the performance chart data on the dashboard page
  • Guided analysis feature
  • Frequently asked questions
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 26 mins read

The Wonderland of Dynamic Tracing (Part 1 of 3)

dynamic-tracing openresty-xray
  • Dynamic Tracing
  • What It Is
  • Too Good to be True?
  • How it Works
  • Still Having Doubts?
  • The Advantages of Dynamic Tracing
  • DTrace
  • SystemTap
  • DTrace and SystemTap
  • Applications of SystemTap in Production
Photo by Philip Brown
  • Dynamic Tracing
  • What It Is
  • Too Good to be True?
  • How it Works
  • Still Having Doubts?
  • The Advantages of Dynamic Tracing
  • DTrace
  • SystemTap
  • DTrace and SystemTap
  • Applications of SystemTap in Production

OpenResty XRay Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 6 mins read

The Wonderland of Dynamic Tracing (Part 3 of 3)

dynamic-tracing openresty-xray
  • Dynamic Tracing Support in Linux Kernels
  • Hardware Tracing
  • Analyze Remains of Dead Process
  • Traditional Debugging Technologies
  • A Messy World of Debugging
  • OpenResty XRay
Photo by L N
  • Dynamic Tracing Support in Linux Kernels
  • Hardware Tracing
  • Analyze Remains of Dead Process
  • Traditional Debugging Technologies
  • A Messy World of Debugging
  • OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 8 mins read

How a Single "0" Took Down Bilibili — Every Server at 100% CPU, and Reboots Didn't Help

dynamic-tracing openresty-xray bilibili
  • The Platform Behind Hundreds of Millions of Streams
  • The July 2021 Bilibili Outage: When Rebooting Doesn’t Help
  • Finding the Root Cause with CPU Flame Graphs
  • One Type Mismatch, Entire System Down
Photo by Yichun Zhang
  • The Platform Behind Hundreds of Millions of Streams
  • The July 2021 Bilibili Outage: When Rebooting Doesn’t Help
  • Finding the Root Cause with CPU Flame Graphs
  • One Type Mismatch, Entire System Down

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 5 mins read

Install OpenResty XRay’s Agents on Kubernetes cluster

tutorial openresty-xray kubernetes agent install
  • Logging in to the Console
  • Installing the Agent on Kubernetes cluster
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay
  • Logging in to the Console
  • Installing the Agent on Kubernetes cluster
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 4 mins read

Install OpenResty XRay’s Agents on Amazon Linux via Package Bundles

tutorial openresty-xray amazon-linux2 agent install
  • Logging in to the Console
  • Installing the Agent via Bundle Packages
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay
  • Logging in to the Console
  • Installing the Agent via Bundle Packages
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 5 mins read

Install OpenResty XRay’s Agents on Ubuntu via Deb Packages

tutorial openresty-xray ubuntu agent install
  • Logging in to the Console
  • Installing the Agent via Deb Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay
  • Logging in to the Console
  • Installing the Agent via Deb Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 4 mins read

Install OpenResty XRay’s Agents on CentOS via RPM Packages

tutorial openresty-xray centos agent install
  • Logging in to the Console
  • Installing the Agent via RPM Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay
  • Logging in to the Console
  • Installing the Agent via RPM Packages
  • Checking the Agent Status and Logs
  • Configuring and Detecting Applications
  • Initiating Analyzers and Viewing Insights
  • Install Another Agent
  • What is OpenResty XRay

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 6 mins read

How to deploy the on-premises version of OpenResty XRay on Microsoft's Azure cloud

tutorial openresty-xray azure
  • Create a subscription and a resource group
  • Create the Azure Kubernetes service
  • Prepare the environment variables
  • Log in to Azure from the command line
  • Create the namespace and secret for Kubernetes
  • Create the Azure Disk
  • Update the configuration file for the persistent volume
  • Update the Kubernetes configuration file
  • Create the persistent volume
  • Deploy the Kubernetes service
  • Configure the application gateway
  • Create a subscription and a resource group
  • Create the Azure Kubernetes service
  • Prepare the environment variables
  • Log in to Azure from the command line
  • Create the namespace and secret for Kubernetes
  • Create the Azure Disk
  • Update the configuration file for the persistent volume
  • Update the Kubernetes configuration file
  • Create the persistent volume
  • Deploy the Kubernetes service
  • Configure the application gateway

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Debugging High Disk I/O in Go Services on Linux

tutorial openresty-xray go disk-io
  • Identifying the Go process with high disk I/O
  • Tracing Go disk read and write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions
  • Identifying the Go process with high disk I/O
  • Tracing Go disk read and write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 7 mins read

Pinpointing CPU-Hottest Go Code Paths Inside Prometheus (using OpenResty XRay)

tutorial openresty-xray prometheus garbage-collection go
  • Problem: high CPU usage
  • Use the guided analysis feature of OpenResty XRay to spot the CPU-hottest Go code paths
  • Automatic analysis and reports
  • What is OpenResty XRay
  • Problem: high CPU usage
  • Use the guided analysis feature of OpenResty XRay to spot the CPU-hottest Go code paths
  • Automatic analysis and reports
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 6 mins read

CockroachDB High CPU Usage: Profiling a Live Go Server with Flame Graphs

tutorial openresty-xray cpu profiling flame-graph go cockroachdb
  • Problem: CockroachDB high CPU usage
  • Find the most CPU-intensive Go code paths with guided analysis
  • Automatic CPU analysis and reports
  • What is OpenResty XRay
  • Problem: CockroachDB high CPU usage
  • Find the most CPU-intensive Go code paths with guided analysis
  • Automatic CPU analysis and reports
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 4 mins read

Dynamic-Tracing Custom Go Programs with Custom Ylang Analyzers (using OpenResty XRay)

tutorial openresty-xray ylang analyzer go
  • Insert two key-value Pairs into a Go Variable
  • Write a Customize Ylang Analyzer to Dynamically Trace the Go program
  • Test the Results
  • What is OpenResty XRay
  • Insert two key-value Pairs into a Go Variable
  • Write a Customize Ylang Analyzer to Dynamically Trace the Go program
  • Test the Results
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

etcd High CPU Usage: Find the Hottest Go Code Paths with Flame Graphs

tutorial openresty-xray go cpu etcd
  • Symptom: etcd consuming over 70% of a CPU core
  • Use OpenResty XRay Guided Analysis to find the hottest Go code paths
  • Automatic etcd CPU monitoring and reports
  • What is OpenResty XRay
  • Symptom: etcd consuming over 70% of a CPU core
  • Use OpenResty XRay Guided Analysis to find the hottest Go code paths
  • Automatic etcd CPU monitoring and reports
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Go Off-CPU Analysis: Tracing a Running Process Stuck at 2% CPU to a Blocking Shell Call

tutorial openresty-xray go cpu
  • The symptom: Go service CPU usage stays low under load
  • Running off-CPU analysis on the live Go process with OpenResty XRay
  • Root cause: a blocking shell command at a single source line
  • Automatic analysis and reports
  • The symptom: Go service CPU usage stays low under load
  • Running off-CPU analysis on the live Go process with OpenResty XRay
  • Root cause: a blocking shell command at a single source line
  • Automatic analysis and reports

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Diagnosing High Disk I/O in Python Applications with XRay

tutorial openresty-xray python disk-io
  • Identifying the Python process with high disk I/O
  • Tracing Python disk read and write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions
  • Identifying the Python process with high disk I/O
  • Tracing Python disk read and write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Python Memory Profiler: Find the Largest Objects Eating RAM Without Code Changes

tutorial openresty-xray python memory
  • Find which Python process is using the most memory
  • Profile Python memory with guided analysis: find the largest objects and their modules
  • Automatically monitor Python memory usage with scheduled reports
  • What is OpenResty XRay
  • Find which Python process is using the most memory
  • Profile Python memory with guided analysis: find the largest objects and their modules
  • Automatically monitor Python memory usage with scheduled reports
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Python Process Stuck at 8% CPU: Off-CPU Analysis Traces a Blocking subprocess.run Call

tutorial openresty-xray python off-cpu
  • The symptom: Python process CPU usage stays low under heavy requests
  • Find the blocking Python code paths with OpenResty XRay’s Guided Analysis
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author
  • The symptom: Python process CPU usage stays low under heavy requests
  • Find the blocking Python code paths with OpenResty XRay’s Guided Analysis
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 8 mins read

Java Tomcat Slow Response Time: Pinpoint the Exact Slow Request with PCAP

openresty-xray java tomcat latency performance
  • Diagnose Tomcat slow response time by catching the exact slow request
  • Selective packet capture: filter by duration, status, and path
  • Per-request PCAP download for one specific slow request
  • Tell server-side latency from network delay
  • Works for Spring Boot apps with embedded Tomcat
Photo by Yichun Zhang
  • Diagnose Tomcat slow response time by catching the exact slow request
  • Selective packet capture: filter by duration, status, and path
  • Per-request PCAP download for one specific slow request
  • Tell server-side latency from network delay
  • Works for Spring Boot apps with embedded Tomcat

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Perl Process Stuck at 13% CPU: Off-CPU Flame Graphs Pinpoint a Blocking HTTP Call

tutorial openresty-xray perl off-cpu
  • The symptom: Perl process CPU usage stays low under heavy requests
  • Find the blocking Perl code paths with OpenResty XRay’s off-CPU flame graphs
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author
  • The symptom: Perl process CPU usage stays low under heavy requests
  • Find the blocking Perl code paths with OpenResty XRay’s off-CPU flame graphs
  • Automatic analysis and reports in the Insights page
  • FAQ
  • What is OpenResty XRay
  • About The Author

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 6 mins read

Locate the Largest Memory Objects in a Live Perl Process

tutorial openresty-xray perl memory
  • Symptom: a Perl process using high memory in top
  • Profile the process with OpenResty XRay guided analysis to find the largest Perl objects
  • Trace the largest object back to its source file
  • Monitor Perl process memory automatically with Insights reports
  • FAQ
  • What is OpenResty XRay
  • Symptom: a Perl process using high memory in top
  • Profile the process with OpenResty XRay guided analysis to find the largest Perl objects
  • Trace the largest object back to its source file
  • Monitor Perl process memory automatically with Insights reports
  • FAQ
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Why Your Rust Process Has High Disk I/O (and How to Find the Cause)

tutorial openresty-xray rust disk-io
  • Identifying the Rust process with high disk I/O
  • Tracing the hottest Rust disk write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions
  • Identifying the Rust process with high disk I/O
  • Tracing the hottest Rust disk write code paths with flame graphs
  • Automatic disk I/O analysis and reports
  • What is OpenResty XRay
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Tested in Production: The Performance Impact of OpenResty XRay When Tracing Rust Applications

tutorial openresty-xray rust overhead
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ
  • What Happens to CPU, Memory, and Load During Profiling?
  • How Much Does Profiling Affect Throughput and Latency?
  • OpenResty XRay vs. Always-On APM Agents
  • FAQ

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

Rust CPU Profiling: Find the Hottest Code Paths in Sled with OpenResty XRay

tutorial openresty-xray cpu sled rust profiling flame-graph
  • The problem: a Sled-based cache service using over 100% CPU
  • Profile the running Rust process with Guided Analysis
  • Read the Rust CPU flame graph: the #1 hottest code path
  • The #2 hottest code path: get_inner and view_for_key
  • Automatic Rust CPU analysis reports
  • Frequently asked questions
  • The problem: a Sled-based cache service using over 100% CPU
  • Profile the running Rust process with Guided Analysis
  • Read the Rust CPU flame graph: the #1 hottest code path
  • The #2 hottest code path: get_inner and view_for_key
  • Automatic Rust CPU analysis reports
  • Frequently asked questions

OpenResty XRay Sep 18, 2026

OpenResty XRay Updated Sep 18, 2026 11 mins read

From AI Flame Graph Analysis to Verified Fixes: A Coding-Agent Optimization Loop with OpenResty XRay

openresty-xray ai analyzer cpu lua
  • Prerequisite: OpenResty XRay must already be installed on the target machine
  • Your coding agent isn’t short on intelligence—it’s short on runtime visibility
  • Three optimization rounds: 336 → 4,457 → 26,028 → 29,968 RPS
  • Lua + C, two perspectives: why you shouldn’t try to optimize writev
  • FAQ
  • Prerequisite: OpenResty XRay must already be installed on the target machine
  • Your coding agent isn’t short on intelligence—it’s short on runtime visibility
  • Three optimization rounds: 336 → 4,457 → 26,028 → 29,968 RPS
  • Lua + C, two perspectives: why you shouldn’t try to optimize writev
  • FAQ

OpenResty XRay Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 7 mins read

Use C++ to Dynamic-Trace C++ Applications

stl c++ ebpf openresty-xray dynamic-tracing
  • Setting Up the Target C++ Program
  • Crafting the C++ (or Y++) Analyzer
  • Operationalizing the Target and Analyzer
  • Advancing Support for Complex C++ Applications
  • About the Debug Symbols
Photo by Yichun Zhang
  • Setting Up the Target C++ Program
  • Crafting the C++ (or Y++) Analyzer
  • Operationalizing the Target and Analyzer
  • Advancing Support for Complex C++ Applications
  • About the Debug Symbols

OpenResty XRay Aug 20, 2026

OpenResty XRay Updated Aug 20, 2026 7 mins read

Erlang High CPU Usage: PCRE Regex Bottleneck Traced with Flame Graphs

tutorial openresty-xray erlang cpu profiling regex flame-graph beam-vm
  • Observing 200%+ CPU in an Erlang Process
  • Profiling Erlang CPU Usage with OpenResty XRay
  • C-Level Analysis: erts_pcre_exec and PCRE Backtracking
  • Why PCRE Regex Backtracking Is Expensive in the BEAM VM
  • Automatic Monitoring and Reports
  • FAQ: Erlang High CPU Usage
  • What is OpenResty XRay
  • Observing 200%+ CPU in an Erlang Process
  • Profiling Erlang CPU Usage with OpenResty XRay
  • C-Level Analysis: erts_pcre_exec and PCRE Backtracking
  • Why PCRE Regex Backtracking Is Expensive in the BEAM VM
  • Automatic Monitoring and Reports
  • FAQ: Erlang High CPU Usage
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Nginx 'No Debugging Symbols Found'? Rebuild Them Automatically with OpenResty XRay

tutorial openresty-xray debug-symbol nodwarf
  • Confirming Nginx Is Stripped and Debug Symbols Are Missing
  • Rebuild Missing Nginx Debug Symbols Automatically — No Recompile Needed
  • Continuous Analysis: Daily and Weekly Insights Reports
  • FAQ: nginx-dbg, recompiling, and profiling stripped binaries
  • Confirming Nginx Is Stripped and Debug Symbols Are Missing
  • Rebuild Missing Nginx Debug Symbols Automatically — No Recompile Needed
  • Continuous Analysis: Daily and Weekly Insights Reports
  • FAQ: nginx-dbg, recompiling, and profiling stripped binaries

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

Automatic Core Dump Analysis (using OpenResty XRay)

openresty-xray core-dump lua-backtrace luajit dynamic-tracing ebpf
  • Locate the core dump file from a crashed OpenResty/Nginx worker
  • Start automatic (guided) core dump analysis in OpenResty XRay
  • Read the signal, CPU registers, and C backtrace of the crash
  • Follow the Lua backtrace to the exact crashing line
  • Automatic Insights reports for online core dumps
  • Locate the core dump file from a crashed OpenResty/Nginx worker
  • Start automatic (guided) core dump analysis in OpenResty XRay
  • Read the signal, CPU registers, and C backtrace of the crash
  • Follow the Lua backtrace to the exact crashing line
  • Automatic Insights reports for online core dumps

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 6 mins read

Envoy CPU Profiling: Find Hot C++ Paths with Flame Graphs

tutorial openresty-xray cpu envoy flame-graph profiling dynamic-tracing
  • Scenario: Envoy Proxy Running at 90% CPU
  • Profile Envoy CPU with C++ Flame Graphs
  • Continuous CPU Monitoring with Automated Reports
  • What is OpenResty XRay
  • FAQ: Envoy CPU Profiling
  • Scenario: Envoy Proxy Running at 90% CPU
  • Profile Envoy CPU with C++ Flame Graphs
  • Continuous CPU Monitoring with Automated Reports
  • What is OpenResty XRay
  • FAQ: Envoy CPU Profiling

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 8 mins read

How to Diagnose 504 Gateway Timeout Errors in OpenResty & Nginx

tutorial openresty-xray 504 timeout
  • Confirm HTTP 504 gateway timeout errors in the OpenResty/Nginx access log
  • Diagnose the 504 root cause with OpenResty XRay Guided Analysis
  • Slow upstream, slow network link, or a too-short timeout setting
  • Automatic root-cause reports on the Insights page
  • Confirm HTTP 504 gateway timeout errors in the OpenResty/Nginx access log
  • Diagnose the 504 root cause with OpenResty XRay Guided Analysis
  • Slow upstream, slow network link, or a too-short timeout setting
  • Automatic root-cause reports on the Insights page

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Django Memory Profiler: Analyze Object-Level Memory Usage in a Live App

tutorial openresty-xray python memory django
  • Spot a high-memory Django process with ps
  • Profile the Django app’s memory usage with Guided Analysis
  • Read the flame graph: which Python module uses the most memory
  • Monitor Django memory usage automatically with Insights
  • What is OpenResty XRay
  • Spot a high-memory Django process with ps
  • Profile the Django app’s memory usage with Guided Analysis
  • Read the flame graph: which Python module uses the most memory
  • Monitor Django memory usage automatically with Insights
  • What is OpenResty XRay

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 7 mins read

llama.cpp CPU Usage: 400% CPU Traced to ggml Hot Functions

tutorial openresty-xray llm cpu generative-ai llama2 llama.cpp profiling ai
  • Running llama.cpp and Observing 400% CPU Usage
  • Profiling llama.cpp CPU Usage with OpenResty XRay
  • Findings: The Hottest C++ Code Paths
  • What is OpenResty XRay
  • Running llama.cpp and Observing 400% CPU Usage
  • Profiling llama.cpp CPU Usage with OpenResty XRay
  • Findings: The Hottest C++ Code Paths
  • What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Lua High CPU Usage: Find the Hottest Lua Code Path in Nginx/OpenResty

tutorial openresty-xray lua cpu flame-graph profiling
  • The symptom: an Nginx worker process using almost 100% CPU
  • Find the hottest Lua code path with Guided Analysis
  • Monitor Lua CPU usage automatically with Insights reports
  • Frequently asked questions
  • The symptom: an Nginx worker process using almost 100% CPU
  • Find the hottest Lua code path with Guided Analysis
  • Monitor Lua CPU usage automatically with Insights reports
  • Frequently asked questions

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 6 mins read

Kong Plugin High CPU Usage: A Hidden Lua Exception Traced with Flame Graphs

openresty-xray exceptions lua kong nginx cpu
  • The problem: Kong plugin high CPU usage under light traffic
  • Finding the CPU bottleneck with an OpenResty XRay flame graph
  • The result: Kong CPU usage cut from 80% to 50%
Photo by Yichun Zhang
  • The problem: Kong plugin high CPU usage under light traffic
  • Finding the CPU bottleneck with an OpenResty XRay flame graph
  • The result: Kong CPU usage cut from 80% to 50%

OpenResty XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 2026 8 mins read

Find Leaked Lua Tables: the registry / _LOADED (package.loaded) Reference Path in OpenResty XRay

openresty memory-leak openresty-xray case-study
  • How LuaJIT manages memory
  • OpenResty XRay’s command-line tools
  • A leaking Lua table example
  • Breaking down memory by LuaJIT GC object type
  • Reading the lj-gco-ref flame graph: registry, _LOADED, package.loaded
  • Fully-automated Lua memory leak analysis
  • How LuaJIT manages memory
  • OpenResty XRay’s command-line tools
  • A leaking Lua table example
  • Breaking down memory by LuaJIT GC object type
  • Reading the lj-gco-ref flame graph: registry, _LOADED, package.loaded
  • Fully-automated Lua memory leak analysis

OpenResty XRay Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 8 mins read

Real-Time Request Counting against Nginx Processes via YSQL

openresty-xray ysql nginx
  • How to install the run-ysql tool
  • Count total requests served in real time
  • Filter out specific requests
  • Using YSQL in the Web Console
  • True non-invasive tracing
Photo by Yichun Zhang
  • How to install the run-ysql tool
  • Count total requests served in real time
  • Filter out specific requests
  • Using YSQL in the Web Console
  • True non-invasive tracing

OpenResty XRay Sep 9, 2026

OpenResty XRay Updated Sep 9, 2026 11 mins read

Nginx Regex Performance: Find Slow Patterns with Dynamic Tracing

regex openresty-xray dynamic-tracing nginx
  • Prerequisites and Setup
  • Locate Slow Regex with CPU Flame Graphs
  • Performance After Regex Optimization
  • Limit PCRE Backtracking with lua_regex_match_limit
  • Non-Backtracking Engines: RE2 and OpenResty Regex
  • Lua Built-in Patterns as a Regex Alternative
  • Trace Regex Performance in Docker and Kubernetes
  • How the Dynamic-Tracing Tools Work
  • Tool Overhead: Zero Impact When Not Sampling
  • FAQ: Nginx Regex Performance
  • Prerequisites and Setup
  • Locate Slow Regex with CPU Flame Graphs
  • Performance After Regex Optimization
  • Limit PCRE Backtracking with lua_regex_match_limit
  • Non-Backtracking Engines: RE2 and OpenResty Regex
  • Lua Built-in Patterns as a Regex Alternative
  • Trace Regex Performance in Docker and Kubernetes
  • How the Dynamic-Tracing Tools Work
  • Tool Overhead: Zero Impact When Not Sampling
  • FAQ: Nginx Regex Performance

OpenResty XRay Sep 9, 2026

OpenResty XRay Updated Sep 9, 2026 9 mins read

Listing Loaded Lua Modules in OpenResty or Nginx Processes

ylua openresty-xray nginx lua dynamic-tracing
  • System Environment
  • Names of Loaded Lua Modules
  • Running Directly in the Web Console
  • Tracing Applications inside Containers
  • How The Tools are Implemented
  • The Overhead of the Tools
Photo by Yichun Zhang
  • System Environment
  • Names of Loaded Lua Modules
  • Running Directly in the Web Console
  • Tracing Applications inside Containers
  • How The Tools are Implemented
  • The Overhead of the Tools

OpenResty XRay Sep 9, 2026

OpenResty XRay Updated Sep 9, 2026 13 mins read

Nginx High CPU Usage: Find Which Requests Consume the Most CPU

tutorial cpu nginx openresty-xray ysql
  • Prerequisites and Environment Setup
  • Find Which Request Hostname Uses the Most CPU
  • Find Which Request URI Uses the Most CPU
  • Digging Deeper: Why Some Hostnames Use More CPU
  • Running the Tools in the Web Console
  • Tracing Nginx CPU Usage Inside Containers
  • How the CPU Profiling Tools Work
  • The Overhead of the Profiling Tools
  • Frequently Asked Questions
Photo by Yichun Zhang
  • Prerequisites and Environment Setup
  • Find Which Request Hostname Uses the Most CPU
  • Find Which Request URI Uses the Most CPU
  • Digging Deeper: Why Some Hostnames Use More CPU
  • Running the Tools in the Web Console
  • Tracing Nginx CPU Usage Inside Containers
  • How the CPU Profiling Tools Work
  • The Overhead of the Profiling Tools
  • Frequently Asked Questions

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 15 mins read

Ylang in Production: Container Tracing, Stack Unwinding & Core Dumps (Series Part 4)

ylang openresty-xray dynamic-tracing
  • Transparent Container Tracing
  • Efficient Stack Unwinding
  • Analyzing Dead Processes (Core Dumps)
  • Very Low Tracing Overhead
  • Standard Ylang Libraries & Tools
  • Network Filtering & Control
  • The Ylang Compiler’s Implementation
  • Operating System Support
  • Contributions to Open-Source Communities
Photo by Yichun Zhang
  • Transparent Container Tracing
  • Efficient Stack Unwinding
  • Analyzing Dead Processes (Core Dumps)
  • Very Low Tracing Overhead
  • Standard Ylang Libraries & Tools
  • Network Filtering & Control
  • The Ylang Compiler’s Implementation
  • Operating System Support
  • Contributions to Open-Source Communities

OpenResty XRay Aug 6, 2026

OpenResty XRay Updated Aug 6, 2026 11 mins read

Ylang: Regex, Full Control Flow & Transparent Debug Symbol Handling (Series Part 3)

ylang openresty-xray dynamic-tracing
  • The Language Syntax (Continued)
    • String Literals
    • Built-in Regex Support
    • Full Control-Flow Support
    • Floating-Point Number Support
    • Compared to Open-Source Toolchains
  • Transparent Debug Symbol Handling
    • Debug Symbols: No Runtime Overhead
    • Centralized Package Database
    • Fuzzy Matching Debug Symbols
Photo by Yichun Zhang
  • The Language Syntax (Continued)
    • String Literals
    • Built-in Regex Support
    • Full Control-Flow Support
    • Floating-Point Number Support
    • Compared to Open-Source Toolchains
  • Transparent Debug Symbol Handling
    • Debug Symbols: No Runtime Overhead
    • Centralized Package Database
    • Fuzzy Matching Debug Symbols

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 15 mins read

Ylang: A Dynamic Tracing Language for eBPF, SystemTap, GDB, and More (Part 1 of 4)

ylang openresty-xray dynamic-tracing
  • What is Dynamic Tracing
  • Why the “Y” Name
  • Getting Started with Ylang
  • Dynamic Tracing Backends: eBPF+, Stap+, GDB, and ODB
  • Why a Unified Frontend Language for Dynamic Tracing
  • The Ylang Syntax: Genuinely C-Compatible
  • Frequently Asked Questions
Photo by Yichun Zhang
  • What is Dynamic Tracing
  • Why the “Y” Name
  • Getting Started with Ylang
  • Dynamic Tracing Backends: eBPF+, Stap+, GDB, and ODB
  • Why a Unified Frontend Language for Dynamic Tracing
  • The Ylang Syntax: Genuinely C-Compatible
  • Frequently Asked Questions

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 20 mins read

Lua CPU Flame Graphs: Profiling LuaJIT in Production

nginx openresty lua cpu openresty-xray dynamic-tracing luajit
  • What Is a Lua CPU Flame Graph
  • Profiling simple LuaJIT apps: verifying accuracy
  • Profiling complex LuaJIT apps in production
  • Sampling Overhead
  • Production safety: not a single bit changed
  • Compatibility
  • FAQ
Photo by Guido Jansen
  • What Is a Lua CPU Flame Graph
  • Profiling simple LuaJIT apps: verifying accuracy
  • Profiling complex LuaJIT apps in production
  • Sampling Overhead
  • Production safety: not a single bit changed
  • Compatibility
  • FAQ

OpenResty XRay Sep 10, 2026

OpenResty XRay Updated Sep 10, 2026 16 mins read

LuaJIT GC64 Mode: Removing the 2GB Memory Limit

luajit openresty memory openresty-xray
  • The Old Memory Limit
    • When Hitting The Memory Limit
    • The Memory Limit Is Per Process
    • GC-Managed Memory
    • Memory Allocated Outside GC
    • Extending The x64 Mode to The 4 GB Limit
  • The New GC64 Mode
    • How to Enable The GC64 Mode
    • Performance Impact
    • Debugging and Profiling Tool Chains
  • The Old Memory Limit
    • When Hitting The Memory Limit
    • The Memory Limit Is Per Process
    • GC-Managed Memory
    • Memory Allocated Outside GC
    • Extending The x64 Mode to The 4 GB Limit
  • The New GC64 Mode
    • How to Enable The GC64 Mode
    • Performance Impact
    • Debugging and Profiling Tool Chains
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