OpenResty's Official Blog for Technologies & Products

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 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 XRay Aug 24, 2026

OpenResty XRay Updated Aug 24, 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

OpenResty XRay Aug 27, 2026

OpenResty XRay Updated Aug 27, 2026 6 mins read

TCP Packet Capture on Slow Connections: Tracing a 200ms Nginx Request Body Delay

openresty-xray latency network smart-packet-capture nginx

• The Problem
• Analysis: TCP Packet Capture on Slow Connections
• Fully-automated analysis
• What is OpenResty XRay