locks: synchronized vs ReentrantLock vs StampedLock companion code

JMH throughput sweep (1-64 threads), 9:1 read-heavy @Group benchmark, tryLock(timeout) deadlock-avoidance demo, and a JDK21-vs-JDK25 JEP 491 virtual-thread-pinning comparison. Also promotes LICENSE to repo root now that a second module exists.
2026-09-30 06:04:50 +00:00
parent f548d9eeb5
commit 32b8067ecf
25 changed files with 763 additions and 6 deletions
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+# Regenerates every file in output/ using the same commands used to produce the ones
+# committed here. Requires JDK 25 on PATH/JAVA_HOME for the main build, plus a JDK 21
+# install for output/01 (see the comment above that command below).
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+mvn -q package
+
+echo "--- 02: pinning demo (JDK 25, post-JEP-491) ---"
+java -cp target/classes -Djdk.tracePinnedThreads=full com.ankurm.locks.VirtualThreadPinningDemo \
+  > output/02-pinning-jdk25-post-jep491.txt 2>&1 || true
+
+echo "--- 03: tryLock timeout deadlock avoidance ---"
+java -cp target/classes com.ankurm.locks.TryLockTimeoutDemo \
+  > output/03-trylock-timeout-deadlock-avoidance.txt 2>&1
+
+echo "--- 04: IncrementBenchmark thread-count sweep (takes a few minutes) ---"
+{
+  echo '$ java -jar target/benchmarks.jar IncrementBenchmark -t <N> -rf text'
+  for t in 1 2 4 8 16 32 64; do
+    echo "=== threads=$t ==="
+    java -jar target/benchmarks.jar "IncrementBenchmark" -t "$t" -rf text -rff /tmp/jmh-increment-$t.txt
+    cat "/tmp/jmh-increment-$t.txt"
+    echo ""
+  done
+} > output/04-increment-benchmark-sweep.txt
+
+echo "--- 05: ReadHeavyBenchmark (9:1 read:write via @Group) ---"
+java -jar target/benchmarks.jar "ReadHeavyBenchmark" -rf text -rff output/05-read-heavy-benchmark.txt
+
+echo "--- 06: correctness tests ---"
+mvn -q test
+cp target/surefire-reports/com.ankurm.locks.CounterCorrectnessTest.txt output/06-counter-correctness.txt
+
+echo "--- 01: pinning demo on JDK 21 (pre-JEP-491) - needs a separate JDK 21 install ---"
+echo "    javac --release 21 -d /tmp/pinning-jdk21-classes src/main/java/com/ankurm/locks/VirtualThreadPinningDemo.java"
+echo "    java -cp /tmp/pinning-jdk21-classes -Djdk.tracePinnedThreads=full com.ankurm.locks.VirtualThreadPinningDemo"
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+# Quick ad hoc JMH run against one benchmark class, printed to the terminal. Example:
+#   ./scripts/run.sh IncrementBenchmark -t 8
+#   ./scripts/run.sh ReadHeavyBenchmark
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+BENCH="${1:?Usage: run.sh <BenchmarkClassName> [extra jmh args]}"
+shift || true
+
+JAR=target/benchmarks.jar
+[ -f "$JAR" ] || { echo "Run 'mvn package' first."; exit 1; }
+
+java -jar "$JAR" "$BENCH" "$@"