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

Java Java Stream Benchmarking Jmh Java 12

Java Problem Overview

As part of my investigation on the difference between using a complex filter or multiple filters in streams, I notice that performance on Java 12 is way slower than on Java 8.

Is any explanation for those weird results? Did I miss something here?

Configuration:

java 8
- OpenJDK Runtime Environment (build 1.8.0_181-8u181-b13-2~deb9u1-b13)
- OpenJDK 64-Bit Server VM (build 25.181-b13, mixed mode)
java 12
- OpenJDK Runtime Environment (build 12+33)
- OpenJDK 64-Bit Server VM (build 12+33, mixed mode, sharing)
VM options: -XX:+UseG1GC -server -Xmx1024m -Xms1024m
CPU: 8 cores

JMH Throughput Results:

Warmup: 10 iterations, 1 s each
Measurement: 10 iterations, 1 s each
Threads: 1 thread, will synchronize iterations
Units: ops/s

Code

Stream + complex filter

public void complexFilter(ExecutionPlan plan, Blackhole blackhole) {
        long count = plan.getDoubles()
                .stream()
                .filter(d -> d < Math.PI
                        && d > Math.E
                        && d != 3
                        && d != 2)
                .count();

        blackhole.consume(count);
    }

Stream + multiple filters

public void multipleFilters(ExecutionPlan plan, Blackhole blackhole) {
        long count = plan.getDoubles()
                .stream()
                .filter(d -> d > Math.PI)
                .filter(d -> d < Math.E)
                .filter(d -> d != 3)
                .filter(d -> d != 2)
                .count();

        blackhole.consume(count);
    }

Parallel stream + complex filter

public void complexFilterParallel(ExecutionPlan plan, Blackhole blackhole) {
        long count = plan.getDoubles()
                .stream()
                .parallel()
                .filter(d -> d < Math.PI
                        && d > Math.E
                        && d != 3
                        && d != 2)
                .count();

        blackhole.consume(count);
    }

Parallel stream + multiple filters

public void multipleFiltersParallel(ExecutionPlan plan, Blackhole blackhole) {
        long count = plan.getDoubles()
                .stream()
                .parallel()
                .filter(d -> d > Math.PI)
                .filter(d -> d < Math.E)
                .filter(d -> d != 3)
                .filter(d -> d != 2)
                .count();

        blackhole.consume(count);
    }

Old fashion java iteration

public void oldFashionFilters(ExecutionPlan plan, Blackhole blackhole) {
        long count = 0;
        for (int i = 0; i < plan.getDoubles().size(); i++) {
            if (plan.getDoubles().get(i) > Math.PI
                    && plan.getDoubles().get(i) > Math.E
                    && plan.getDoubles().get(i) != 3
                    && plan.getDoubles().get(i) != 2) {
                count = count + 1;
            }
        }

        blackhole.consume(count);
    }

You can try by yourself by running docker command:

For Java 8:

> docker run -it volkodav/java-filter-benchmark:java8

For Java 12:

> docker run -it volkodav/java-filter-benchmark:java12

Source code:

https://github.com/volkodavs/javafilters-benchmarks

Java Solutions

Solution 1 - Java

Thanks, everyone for the help and especially to @Aleksey Shipilev!

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.

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

Content Type	Original Author	Original Content on Stackoverflow
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Solution 1 - Java	Serge	View Answer on Stackoverflow

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

Java Problem Overview

Code

Java Solutions

Solution 1 - Java

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