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Add virtual-threads-benchmark: re-run Spring Boot 4.1 / JDK 25 benchmarks, JEP 491 pinning fixed

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Companion module for the rewritten post 'Virtual Threads on Spring Boot 4.1: The Benchmarks,
Re-Run, and the Pinning Advice That Expired', retitled and re-benchmarked on Boot 4.1.1 /
JDK 25.0.4.1 (the original post was written against Boot 3.4 / JDK 21). Covers: I/O-bound and
CPU-bound throughput (platform vs virtual threads, including a JIT-warmup benchmarking bug this
build caught and fixed), JEP 491 proof that synchronized no longer pins a virtual thread's
carrier across a blocking call as of JDK 24 (obsoleting the old avoid-synchronized advice),
proof that -Djdk.tracePinnedThreads=full is inert on JDK 25, and JEP 506's finalized ScopedValue
API (JDK 25 GA, no --enable-preview, and a different shape than the old preview API). Kept as
its own module rather than a new top-level repository, alongside the existing async/ module,
which already has a stronger dual-JDK JEP 491 proof that this module's docs cross-link to
instead of duplicating.
This commit is contained in:
asmhatre
2026-09-18 08:52:59 +00:00
parent eaa8171966
commit f506b01389
28 changed files with 1085 additions and 0 deletions
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virtual-threads-benchmark/scripts/check-trace-pinned-threads-removed.sh
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#!/usr/bin/env bash
# Confirms -Djdk.tracePinnedThreads=full is inert on this JDK (JEP 491, GA in JDK 24).
# Pre-JDK-24, this flag made a pinned virtual thread print a stack trace to stdout while
# pinned. Runs PinningTraceCheckMain (which holds a monitor across Thread.sleep(200) on a
# virtual thread) once without the flag and once with it, and diffs stdout. Output:
# docs/output/03b-trace-pinned-threads-removed.txt. See docs/03-pinning-diagnosis.md.
set -euo pipefail
cd "$(dirname "$0")/.."
mkdir -p docs/output
OUT=docs/output/03b-trace-pinned-threads-removed.txt
echo "java -version:" > "$OUT"
java -version 2>&1 | grep -v "^Picked up JAVA_TOOL_OPTIONS" >> "$OUT"
echo "" >> "$OUT"
echo "-- without -Djdk.tracePinnedThreads=full --" >> "$OUT"
java -cp target/classes com.ankurm.vthreads.PinningTraceCheckMain 2>&1 | grep -v "^Picked up JAVA_TOOL_OPTIONS" >> "$OUT"
echo "" >> "$OUT"
echo "-- with -Djdk.tracePinnedThreads=full --" >> "$OUT"
java -Djdk.tracePinnedThreads=full -cp target/classes com.ankurm.vthreads.PinningTraceCheckMain 2>&1 | grep -v "^Picked up JAVA_TOOL_OPTIONS" >> "$OUT"
echo "" >> "$OUT"
if grep -q "Thread\[#" "$OUT" && grep -qi "monitors:" "$OUT"; then
echo "RESULT: a pinned-thread stack trace WAS printed -- flag still functional on this JDK" >> "$OUT"
else
echo "RESULT: no pinned-thread stack trace was printed by either run -- the flag is inert on this JDK, consistent with JEP 491" >> "$OUT"
fi
cat "$OUT"