jmh-basics: JMH tutorial module (dead-code elimination, Blackhole, constant folding, warmup/forks, state scopes, -prof gc)

Eight benchmark/demo classes, a deterministic test suite, and 12 captured output files generated by scripts/run-all.sh on JDK 25.0.5 (Temurin) with JMH 1.37. Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b6Fj2JNt7dRev4pZPe
2026-11-08 18:31:11 +00:00
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+# JMH version: 1.37
+# VM version: JDK 25.0.5, OpenJDK 64-Bit Server VM, 25.0.5+8-LTS
+# VM invoker: /tmp/tools/jdk-25.0.5+8/bin/java
+# Blackhole mode: compiler (auto-detected, use -Djmh.blackhole.autoDetect=false to disable)
+# Warmup: 3 iterations, 1 s each
+# Measurement: 8 iterations, 1 s each
+# Timeout: 10 min per iteration
+# Threads: 1 thread, will synchronize iterations
+# Benchmark mode: Average time, time/op
+# Benchmark: com.ankurm.jmhbasics.ForkingBenchmark.measure_1_c1
+
+# Run progress: 0.00% complete, ETA 00:00:33
+# Fork: N/A, test runs in the host VM
+# *** WARNING: Non-forked runs may silently omit JVM options, mess up profilers, disable compiler hints, etc. ***
+# *** WARNING: Use non-forked runs only for debugging purposes, not for actual performance runs. ***
+# Warmup Iteration   1: 1.169 ns/op
+# Warmup Iteration   2: 0.972 ns/op
+# Warmup Iteration   3: 0.891 ns/op
+Iteration   1: 0.797 ns/op
+Iteration   2: 1.058 ns/op
+Iteration   3: 0.842 ns/op
+Iteration   4: 0.892 ns/op
+Iteration   5: 0.870 ns/op
+Iteration   6: 1.155 ns/op
+Iteration   7: 0.884 ns/op
+Iteration   8: 0.800 ns/op
+
+Result "com.ankurm.jmhbasics.ForkingBenchmark.measure_1_c1":
+  0.912 ±(99.9%) 0.244 ns/op [Average]
+  (min, avg, max) = (0.797, 0.912, 1.155), stdev = 0.128
+  CI (99.9%): [0.668, 1.156] (assumes normal distribution)
+
+
+# JMH version: 1.37
+# VM version: JDK 25.0.5, OpenJDK 64-Bit Server VM, 25.0.5+8-LTS
+# VM invoker: /tmp/tools/jdk-25.0.5+8/bin/java
+# Blackhole mode: compiler (auto-detected, use -Djmh.blackhole.autoDetect=false to disable)
+# Warmup: 3 iterations, 1 s each
+# Measurement: 8 iterations, 1 s each
+# Timeout: 10 min per iteration
+# Threads: 1 thread, will synchronize iterations
+# Benchmark mode: Average time, time/op
+# Benchmark: com.ankurm.jmhbasics.ForkingBenchmark.measure_2_c2
+
+# Run progress: 33.33% complete, ETA 00:00:22
+# Fork: N/A, test runs in the host VM
+# *** WARNING: Non-forked runs may silently omit JVM options, mess up profilers, disable compiler hints, etc. ***
+# *** WARNING: Use non-forked runs only for debugging purposes, not for actual performance runs. ***
+# Warmup Iteration   1: 1.287 ns/op
+# Warmup Iteration   2: 1.593 ns/op
+# Warmup Iteration   3: 2.833 ns/op
+Iteration   1: 3.000 ns/op
+Iteration   2: 2.695 ns/op
+Iteration   3: 2.754 ns/op
+Iteration   4: 2.416 ns/op
+Iteration   5: 2.173 ns/op
+Iteration   6: 2.287 ns/op
+Iteration   7: 2.217 ns/op
+Iteration   8: 2.100 ns/op
+
+Result "com.ankurm.jmhbasics.ForkingBenchmark.measure_2_c2":
+  2.455 ±(99.9%) 0.620 ns/op [Average]
+  (min, avg, max) = (2.100, 2.455, 3.000), stdev = 0.324
+  CI (99.9%): [1.835, 3.075] (assumes normal distribution)
+
+
+# JMH version: 1.37
+# VM version: JDK 25.0.5, OpenJDK 64-Bit Server VM, 25.0.5+8-LTS
+# VM invoker: /tmp/tools/jdk-25.0.5+8/bin/java
+# Blackhole mode: compiler (auto-detected, use -Djmh.blackhole.autoDetect=false to disable)
+# Warmup: 3 iterations, 1 s each
+# Measurement: 8 iterations, 1 s each
+# Timeout: 10 min per iteration
+# Threads: 1 thread, will synchronize iterations
+# Benchmark mode: Average time, time/op
+# Benchmark: com.ankurm.jmhbasics.ForkingBenchmark.measure_3_c1
+
+# Run progress: 66.67% complete, ETA 00:00:11
+# Fork: N/A, test runs in the host VM
+# *** WARNING: Non-forked runs may silently omit JVM options, mess up profilers, disable compiler hints, etc. ***
+# *** WARNING: Use non-forked runs only for debugging purposes, not for actual performance runs. ***
+# Warmup Iteration   1: 2.188 ns/op
+# Warmup Iteration   2: 2.224 ns/op
+# Warmup Iteration   3: 2.666 ns/op
+Iteration   1: 2.274 ns/op
+Iteration   2: 2.184 ns/op
+Iteration   3: 2.297 ns/op
+Iteration   4: 2.201 ns/op
+Iteration   5: 2.344 ns/op
+Iteration   6: 2.517 ns/op
+Iteration   7: 2.654 ns/op
+Iteration   8: 2.302 ns/op
+
+Result "com.ankurm.jmhbasics.ForkingBenchmark.measure_3_c1":
+  2.347 ±(99.9%) 0.307 ns/op [Average]
+  (min, avg, max) = (2.184, 2.347, 2.654), stdev = 0.161
+  CI (99.9%): [2.040, 2.654] (assumes normal distribution)
+
+
+# Run complete. Total time: 00:00:33
+
+REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
+why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
+experiments, perform baseline and negative tests that provide experimental control, make sure
+the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
+Do not assume the numbers tell you what you want them to tell.
+
+NOTE: Current JVM experimentally supports Compiler Blackholes, and they are in use. Please exercise
+extra caution when trusting the results, look into the generated code to check the benchmark still
+works, and factor in a small probability of new VM bugs. Additionally, while comparisons between
+different JVMs are already problematic, the performance difference caused by different Blackhole
+modes can be very significant. Please make sure you use the consistent Blackhole mode for comparisons.
+
+Benchmark                      Mode  Cnt  Score   Error  Units
+ForkingBenchmark.measure_1_c1  avgt    8  0.912 ± 0.244  ns/op
+ForkingBenchmark.measure_2_c2  avgt    8  2.455 ± 0.620  ns/op
+ForkingBenchmark.measure_3_c1  avgt    8  2.347 ± 0.307  ns/op