Add jfr-demo: JFR + Mission Control profiling of a live Spring Boot app

Custom OrderProcessed event, CPU/allocation/lock workloads, a diagnostic endpoint over the JVM's live FlightRecorder state, a JUnit test using the jdk.jfr.Recording API, and nine captured recordings (flagship, mid-flight snapshot, isolated vs concurrent threshold comparisons, and a real dump+stop duplication bug) with their docs/output/*.txt transcripts.
2026-10-01 04:37:26 +00:00
commit c7eccd1db5
40 changed files with 1326 additions and 0 deletions
@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+# Regenerates every file under docs/output/.
+#
+# 01 comes from the JUnit test suite (jdk.jfr.Recording API, in-process).
+# 02-10 come from starting the real app and driving it with jcmd + curl,
+# exactly as described in the post. 11 comes from a standalone driver class.
+#
+# This script assumes JAVA_HOME points at a JDK with jfr/jcmd on PATH, and
+# that no other jfr-demo.jar is already running on port 8080.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+echo "== 01: in-process custom-event test =="
+mvn -q -B test
+
+echo "== 11: broken-event-pattern standalone demo =="
+mvn -q -B -DskipTests package
+java -cp target/classes com.ankurm.jfr.events.BrokenEventPatternDemo \
+  | tee /tmp/broken-event-output.txt
+# docs/output/11-broken-event-pattern.txt is written by hand from this run's
+# output plus commentary; regenerate it manually if the numbers change.
+
+echo "== starting app for the live jcmd-driven captures =="
+scripts/run.sh -d
+PID=$(ps -eo pid,cmd | grep '[j]fr-demo.jar' | awk '{print $1}' | head -1)
+echo "app pid: $PID"
+
+echo "== 02-10: live recording capture =="
+scripts/capture-jfr.sh "$PID"
+# docs/output/02 through 10 are written by hand from the jfr print/summary
+# output of recordings/live-demo.jfr and the comparison recordings below;
+# regenerate them manually if the workload or JDK version changes.
+
+echo "== threshold-comparison recordings (docs/output/07, 08) =="
+jcmd "$PID" JFR.start name=soloDefault settings=default
+for i in $(seq 1 40); do curl -s "localhost:8080/api/lock/contend?workers=2&holdMillis=12" -o /dev/null; done
+jcmd "$PID" JFR.stop name=soloDefault filename="$(pwd)/recordings/solo-default.jfr"
+
+jcmd "$PID" JFR.start name=soloProfile settings=profile
+for i in $(seq 1 40); do curl -s "localhost:8080/api/lock/contend?workers=2&holdMillis=12" -o /dev/null; done
+jcmd "$PID" JFR.stop name=soloProfile filename="$(pwd)/recordings/solo-profile.jfr"
+
+jcmd "$PID" JFR.start name=soloDefault2 settings=default
+for i in $(seq 1 10); do curl -s "localhost:8080/api/lock/contend?workers=2&holdMillis=35" -o /dev/null; done
+jcmd "$PID" JFR.stop name=soloDefault2 filename="$(pwd)/recordings/solo-default-longhold.jfr"
+
+jcmd "$PID" JFR.start name=cmpA settings=default
+jcmd "$PID" JFR.start name=cmpB settings=profile
+for i in $(seq 1 40); do curl -s "localhost:8080/api/lock/contend?workers=2&holdMillis=12" -o /dev/null; done
+jcmd "$PID" JFR.stop name=cmpA filename="$(pwd)/recordings/compare-default.jfr"
+jcmd "$PID" JFR.stop name=cmpB filename="$(pwd)/recordings/compare-profile.jfr"
+
+for p in $(ps -eo pid,cmd | grep '[j]fr-demo.jar' | awk '{print $1}'); do kill -9 "$p"; done
+echo "all recordings regenerated under recordings/"