Mystifying microbenchmark result for stream API on Java 12 vs. Java 8 with -gc true

After applied changes to JMH benchmark, the results look more realistic (?)

Changes:

Change the setup method to be executed before/after each iteration of the benchmark.

@Setup(Level.Invocation) -> @Setup(Level.Iteration)

Stop JMH forcing GC between iterations. Forcing Full GC before each iteration is quite likely to throw off GC heuristics. (c) Aleksey Shipilev

-gc true -> -gc false

Note: gc false by default.>/p>

Comparison tables

Based on new performance benchmarks there is no performance degradation on Java 12 compare to Java 8.

Note: After those changes, the throughput error for a small array size significantly increased for more than 100%, for a large dataset remain the same.

Raw results

Java 8

# Run complete. Total time: 04:36:29

Benchmark                                (arraySize)   Mode  Cnt         Score         Error  Units
FilterBenchmark.complexFilter                     10  thrpt   50   5947577.648 ±  257535.736  ops/s
FilterBenchmark.complexFilter                    100  thrpt   50   3131081.555 ±   72868.963  ops/s
FilterBenchmark.complexFilter                   1000  thrpt   50    489666.688 ±    6539.466  ops/s
FilterBenchmark.complexFilter                  10000  thrpt   50     17297.424 ±      93.890  ops/s
FilterBenchmark.complexFilter                 100000  thrpt   50      1398.702 ±      72.820  ops/s
FilterBenchmark.complexFilter                1000000  thrpt   50        81.309 ±       0.547  ops/s
FilterBenchmark.complexFilterParallel             10  thrpt   50     24515.743 ±     450.363  ops/s
FilterBenchmark.complexFilterParallel            100  thrpt   50     25584.773 ±     290.249  ops/s
FilterBenchmark.complexFilterParallel           1000  thrpt   50     24313.066 ±     425.817  ops/s
FilterBenchmark.complexFilterParallel          10000  thrpt   50     11909.085 ±      51.534  ops/s
FilterBenchmark.complexFilterParallel         100000  thrpt   50      3260.864 ±     522.565  ops/s
FilterBenchmark.complexFilterParallel        1000000  thrpt   50       406.297 ±      96.590  ops/s
FilterBenchmark.multipleFilters                   10  thrpt   50   3785766.911 ±   27971.998  ops/s
FilterBenchmark.multipleFilters                  100  thrpt   50   1806210.041 ±   11578.529  ops/s
FilterBenchmark.multipleFilters                 1000  thrpt   50    211435.445 ±   28585.969  ops/s
FilterBenchmark.multipleFilters                10000  thrpt   50     12614.670 ±     370.086  ops/s
FilterBenchmark.multipleFilters               100000  thrpt   50      1228.127 ±      21.208  ops/s
FilterBenchmark.multipleFilters              1000000  thrpt   50        99.149 ±       1.370  ops/s
FilterBenchmark.multipleFiltersParallel           10  thrpt   50     23896.812 ±     255.117  ops/s
FilterBenchmark.multipleFiltersParallel          100  thrpt   50     25314.613 ±     169.724  ops/s
FilterBenchmark.multipleFiltersParallel         1000  thrpt   50     23113.388 ±     305.605  ops/s
FilterBenchmark.multipleFiltersParallel        10000  thrpt   50     12676.057 ±     119.555  ops/s
FilterBenchmark.multipleFiltersParallel       100000  thrpt   50      3373.367 ±     211.108  ops/s
FilterBenchmark.multipleFiltersParallel      1000000  thrpt   50       477.870 ±      70.878  ops/s
FilterBenchmark.oldFashionFilters                 10  thrpt   50  45874144.758 ± 2210325.177  ops/s
FilterBenchmark.oldFashionFilters                100  thrpt   50   4902625.828 ±   60397.844  ops/s
FilterBenchmark.oldFashionFilters               1000  thrpt   50    662102.438 ±    5038.465  ops/s
FilterBenchmark.oldFashionFilters              10000  thrpt   50     29390.911 ±     257.311  ops/s
FilterBenchmark.oldFashionFilters             100000  thrpt   50      1999.032 ±       6.829  ops/s
FilterBenchmark.oldFashionFilters            1000000  thrpt   50       200.564 ±       1.695  ops/s

Java 12

# Run complete. Total time: 04:36:20

Benchmark                                (arraySize)   Mode  Cnt         Score         Error  Units
FilterBenchmark.complexFilter                     10  thrpt   50  10338525.553 ? 1677693.433  ops/s
FilterBenchmark.complexFilter                    100  thrpt   50   4381301.188 ?  287299.598  ops/s
FilterBenchmark.complexFilter                   1000  thrpt   50    607572.430 ?    9367.026  ops/s
FilterBenchmark.complexFilter                  10000  thrpt   50     30643.286 ?     472.033  ops/s
FilterBenchmark.complexFilter                 100000  thrpt   50      1450.341 ?       3.730  ops/s
FilterBenchmark.complexFilter                1000000  thrpt   50       138.996 ?       2.052  ops/s
FilterBenchmark.complexFilterParallel             10  thrpt   50     21289.444 ?     183.245  ops/s
FilterBenchmark.complexFilterParallel            100  thrpt   50     20105.239 ?     124.759  ops/s
FilterBenchmark.complexFilterParallel           1000  thrpt   50     19418.830 ?     141.664  ops/s
FilterBenchmark.complexFilterParallel          10000  thrpt   50     13874.585 ?     104.418  ops/s
FilterBenchmark.complexFilterParallel         100000  thrpt   50      5334.947 ?      25.452  ops/s
FilterBenchmark.complexFilterParallel        1000000  thrpt   50       781.046 ?       9.687  ops/s
FilterBenchmark.multipleFilters                   10  thrpt   50   5460308.048 ?  478157.935  ops/s
FilterBenchmark.multipleFilters                  100  thrpt   50   2227583.836 ?  113078.932  ops/s
FilterBenchmark.multipleFilters                 1000  thrpt   50    287157.190 ?    1114.346  ops/s
FilterBenchmark.multipleFilters                10000  thrpt   50     16268.016 ?     704.735  ops/s
FilterBenchmark.multipleFilters               100000  thrpt   50      1531.516 ?       2.729  ops/s
FilterBenchmark.multipleFilters              1000000  thrpt   50       123.881 ?       1.525  ops/s
FilterBenchmark.multipleFiltersParallel           10  thrpt   50     20403.993 ?     147.247  ops/s
FilterBenchmark.multipleFiltersParallel          100  thrpt   50     19426.222 ?      96.979  ops/s
FilterBenchmark.multipleFiltersParallel         1000  thrpt   50     17692.433 ?      67.606  ops/s
FilterBenchmark.multipleFiltersParallel        10000  thrpt   50     12108.482 ?      34.500  ops/s
FilterBenchmark.multipleFiltersParallel       100000  thrpt   50      3782.756 ?      22.044  ops/s
FilterBenchmark.multipleFiltersParallel      1000000  thrpt   50       589.972 ?      71.448  ops/s
FilterBenchmark.oldFashionFilters                 10  thrpt   50  41024334.062 ? 1374663.440  ops/s
FilterBenchmark.oldFashionFilters                100  thrpt   50   6011852.027 ?  246202.642  ops/s
FilterBenchmark.oldFashionFilters               1000  thrpt   50    553243.594 ?    2217.912  ops/s
FilterBenchmark.oldFashionFilters              10000  thrpt   50     29188.753 ?     580.958  ops/s
FilterBenchmark.oldFashionFilters             100000  thrpt   50      2061.738 ?       8.456  ops/s
FilterBenchmark.oldFashionFilters            1000000  thrpt   50       196.105 ?       3.203  ops/s