Skip to content

JFR Query

JFR Query Notebook — line chart, flamegraph, bar chart, heatmap, pie chart, histogram

Analyse Java Flight Recorder files with SQL. JFR Query converts a .jfr recording into a DuckDB database and lets you query it — either from the command line or through a notebook-style web UI where every cell can be a SQL query, a chart, or prose.

→ Open the live web app

Features

  • Notebook-style analysis — compose SQL cells, prose, and charts in one document; inline ${SELECT …} expressions embed query results directly in text
  • 12 chart types — line, bar, scatter, heatmap, flamegraph, histogram, box plot, area, pie, Gantt, range, and table — all with interactive tooltips
  • Built-in templates — ready-made analyses for GC, heap allocation, threading, and exceptions; open from the New from template button
  • Variable controls — parameterise queries with sliders, dropdowns, and text inputs; every chart re-evaluates when a variable changes
  • Works offline — drop a .jfr file directly on the web app; the entire pipeline (JFR parsing + DuckDB queries) runs in the browser via WebAssembly

Quick Start

# Start the notebook UI
java -jar query.jar serve myrecording.jfr
# Open http://localhost:4244

See Getting Started for download options and how to use the live web app without installing anything.

How it works

JFR events are mapped to DuckDB tables: each event type becomes a table, nested structs become either inlined columns or joined lookup tables, and stack traces are stored as flat arrays of method IDs with convenience top-frame columns for fast queries. A library of built-in SQL views and macros hides the join complexity for common analyses.

The web app runs the same Java importer compiled to WebAssembly via GraalVM, so dropping a .jfr file on the browser page runs the full import pipeline locally — no server required.

Documentation
Getting Started Install, first query, web UI
CLI Commands import, query, serve, views, macros
Web UI & Notebooks Cells, variables, live coupling
Notebook Format Markdown format, syntax reference
Plot DSL All chart types with examples
Variables Variable scoping and controls
Built-in Views & Macros SQL library reference
JFR to DuckDB Mapping How JFR becomes tables
Browser Architecture WASM pipeline internals