JFR Viewer

JFR Viewer is a developer-focused tool that transforms Java Flight Recorder data into a structured, audit-ready view of JVM behavior. It accepts a .jfr file upload and returns an organized report of events, durations, and resource usage. The primary users are Java developers, performance engineers, and site reliability engineers who need rapid insight after a deployment or during incident investigations. Typical scenarios include diagnosing long GC pauses, identifying memory allocation hotspots, tracing thread contention, and validating JVM tuning changes. The tool emphasizes correctness and traceability over visual polish, delivering deterministic aggregates and export-ready data.
Core logic decodes the JFR binary stream, maps events to canonical types, and associates each event with relevant JVM components (threads, classes, GC regions). It computes per-type counts, total durations, and weighted CPU time; ranks hotspots; and aggregates GC pause times and allocation rates. Optional features enable filtering by time window, event type, and stack traces; it can compare multiple runs to reveal regression or improvement trends. All calculations respect standard JFR semantics and units, with time in nanoseconds and memory in bytes.
Audience benefits include faster root-cause analysis, reduced MTTR, and more informed capacity planning and tuning decisions. Unique value lies in streaming-safe parsing capable of handling large logs, exact event-level aggregates, and exportable data without requiring a separate visualization layer. Use cases encompass production incident retrospectives, pre-release performance validation, and JVM tuning verification across multiple environments.
Core features and outputs cover: per-event counts, total duration, GC pause metrics, allocation rates, thread activity, and hotspot rankings; optional exports to JSON or CSV; and time-range comparisons across runs.