Performance · OpenResty Official Blog

Performance

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 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

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 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

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