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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/src/main/java/com/ankurm/vthreads/PinningTraceCheckMain.java
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package com.ankurm.vthreads;
/**
* Standalone (no Spring context) check that -Djdk.tracePinnedThreads=full is inert on this
* JDK. Pre-JDK-24, this flag made the JVM print a stack trace to stdout every time a virtual
* thread pinned its carrier. JEP 491 removed the property along with most of the pinning it
* used to report on: "setting it on the command line will have no effect." Run via
* scripts/check-trace-pinned-threads-removed.sh, which invokes this twice (with and without
* the flag) and diffs the output. See docs/03-pinning-diagnosis.md.
*/
public class PinningTraceCheckMain {
public static void main(String[] args) throws Exception {
System.out.println("java.version=" + System.getProperty("java.version"));
System.out.println("jdk.tracePinnedThreads=" + System.getProperty("jdk.tracePinnedThreads"));
System.out.println("Running a virtual thread that holds a monitor across Thread.sleep(200)...");
Thread vt = Thread.ofVirtual().start(() -> {
try {
PinningDemoService.doWorkHoldingMonitor(200);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
});
vt.join();
System.out.println("Done. If jdk.tracePinnedThreads still worked on this JDK, a pinned-thread " +
"stack trace would have printed above while the virtual thread was inside doWorkHoldingMonitor.");
}
}