OpenResty's Official Blog for Technologies & Products

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?

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

OPENRESTY Aug 27, 2026

OPENRESTY Updated Aug 27, 2026 12 mins read

P99 Latency in a D Service Cut 73%: Conservative GC Meets an O(n) Query Under Load

d-lang flame-graph performance garbage-collection

• Analyzing GC Traps and Business Hotspots in the Flame Graph
• Optimization Roadmap: Why Sequence Is More Important Than Action
• Conclusion: From Code Logic to Runtime Reality

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

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

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 7 mins read

PHP High CPU Usage: Find the Hottest Code Path with OpenResty XRay

tutorial openresty-xray php cpu flame-graph profiling

• Problem: high CPU usage
• Find which PHP function is using the CPU with OpenResty XRay Guided Analysis
• Read the CPU flame graph and the hottest PHP and C 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

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

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Golang High CPU Usage: Regex Compilation Burned 36.8% of CPU Time

tutorial openresty-xray go cpu profiling regex flame-graph

• Observing High CPU Usage in a Go Process
• Profiling Go CPU Usage with OpenResty XRay
• Automatic Monitoring and Reports
• What is OpenResty XRay

OpenResty XRay Aug 28, 2026

OpenResty XRay Updated Aug 28, 2026 6 mins read

Perl High CPU Usage: 100% CPU Traced to a Regex Hotspot with Flame Graphs

tutorial openresty-xray perl cpu profiling regex flame-graph dancer2

• Observing 100% CPU Usage in a Perl Process
• Profiling Perl CPU Usage with OpenResty XRay
• Automatic Monitoring and Reports
• 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