OpenResty's Official Blog for Technologies & Products

OpenResty XRay Aug 11, 2026

OpenResty XRay Updated Aug 11, 2026 9 mins read

Hunting Down a Silent Memory Leak in OpenResty Without a Reboot

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• A Complete Dissection of a Production Memory Leak
• Why Are These Problems Nearly Unsolvable?
• A System Transformation
• When Performance Issues Go Beyond Just Tools

OpenResty XRay Aug 12, 2026

OpenResty XRay Updated Aug 12, 2026 4 mins read

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

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• 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 Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 7 mins read

When a "Black Box" Plugin Consumes 45% CPU: How We Pinpointed Lua Line 93 Without Source Code

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• When perf Meets the Black Box
• From Sampling to Full-Stack Dynamic Tracing
• Uncovering the Evidence Trail
• From What happene to Why
• Summary

OpenResty XRay Aug 19, 2026

OpenResty XRay Updated Aug 19, 2026 9 mins read

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

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• 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 14, 2026

OpenResty XRay Updated Aug 14, 2026 9 mins read

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

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• 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 Jun 26, 2026

OpenResty XRay Updated Jun 26, 2026 4 mins read

Double Bottleneck Concurrency? OpenResty XRay Multi-dimensional Analysis Solves Performance Challenges

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• Overall CPU Usage Analysis
• In-depth Module Analysis
• Analysis of Compression Strategies
• Analysis Conclusions
• Optimization Solutions

OpenResty XRay Jul 24, 2026

OpenResty XRay Updated Jul 24, 2026 11 mins read

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

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• 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 17, 2026

OpenResty XRay Updated Aug 17, 2026 7 mins read

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

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• 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 12, 2026

OpenResty XRay Updated Aug 12, 2026 7 mins read

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

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• 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