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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.
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asmhatre
2026-09-18 08:52:59 +00:00
parent eaa8171966
commit f506b01389
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virtual-threads-benchmark/docs/output/03a-pinning-jep491-proof.txt
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JEP 491 proof: synchronized held across Thread.sleep, JDK 25.0.4.1
==================================================================
availableProcessors (default virtual-thread carrier pool size) = 2
virtual threads = 60, each holds a DISTINCT monitor for 250ms
predicted wall time IF PINNED (pre-JDK-24 behaviour): ~7500ms
predicted wall time IF NOT PINNED (JDK 24+ behaviour): ~250ms, independent of carrier count
actual wall time: 251ms
verdict: NOT PINNED -- matches JEP 491's documented JDK 24+ behaviour