ReplaceBenchmark.java

package benchmarks.regex;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;
import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

public class ReplaceBenchmark {

    @State(Scope.Benchmark)
    public static class InputClass {
        public List<String> testList;

        @Setup(Level.Trial)
        public void setUp() {
            testList = new ArrayList<>(
                Arrays.asList(
                    "HMHX-5I16-O6MU-N63O-YG8G-AOF2-756C",
                    "LAHR-PX03-DID4-EKKB-BJ7P-6U0D-UDCT",
                    "V0OS-SSUE-HLVY-IP4X-1QCN-0V79-2K7Q",
                    "712T-JGAV-1DGU-GJS9-EOI0-4KXJ-10FX",
                    "2OFJ-VZ9O-O80I-4ZX0-SQ6O-NVBB-IP0Z",
                    "5ZPZ-U3DJ-1CWK-YZEK-A0RF-JLW6-N0GW",
                    "1FQB-O06U-XFHP-TK3U-RKF5-KA7N-NV2I",
                    "UL0R-87OD-VN87-MW31-NZ87-CGMM-3GHJ",
                    "SQ94-CUG0-I73S-K8XX-2EOH-0X6S-VIDB",
                    "4EZC-S0Y5-NPZ6-GBEO-1G9U-T3D0-8VYM",
                    "Z3H5-Q42K-0U4W-TCBU-H3VL-5B4Y-A1R9",
                    "UYFK-I56S-APWC-7DA7-NJMH-I9MK-KA9X",
                    "V2X3-XMK3-CT2Q-TLLZ-KZHH-ENNN-8CVI",
                    "LQFL-T3VO-QOLJ-R5KZ-U6HO-XFUN-DP88",
                    "CEDZ-XH24-WERJ-QHMS-T3GS-8KZP-AI7J",
                    "7R14-7D6U-SWXX-XI06-PCJQ-1USM-LJ9L",
                    "QW0D-YDE2-K9JP-8U5A-MZ5L-7DZG-I5XE",
                    "PYFQ-74GS-UNJR-STA1-W7IY-TM7G-ADME",
                    "W9X4-8717-2W0O-X448-2I50-RLV0-W064",
                    "C0YU-2U5J-QYKP-CRXR-9ARH-2HM7-A225",
                    "D2V4-BGUM-R657-YACZ-QTAX-4167-S3RZ",
                    "WIS1-T3W1-6UT7-GRPR-9YQB-HS38-JN84",
                    "LEMN-CUV0-YUZ5-LJ7T-R15F-FSHA-PFPW",
                    "8QG4-M6K8-UVVY-74JY-T3WX-PB3Q-LODW",
                    "XYHP-JRP0-9X4B-20QJ-5CFD-UWZ5-J56N",
                    "IG1U-UZTH-TF5B-39UA-GKVL-LIYN-YSY0",
                    "NO7Q-1771-DF11-WRDG-XMLJ-04ET-LFA4",
                    "B5YA-VKJP-XUZE-U264-YX0Z-5429-Z3LN",
                    "W2UL-WWEJ-UUK6-RWJY-LTBV-LU7A-CJGA",
                    "1SQH-OD5O-O9RR-Q8QQ-7H13-RSPC-3MRH",
                    "1VE9-RH25-92WI-47OC-7NI5-KLM5-97SB",
                    "XF7F-VWBY-3U3E-GZ9T-RM6H-QXUW-EPX5",
                    "1SSC-QLA4-X2R0-9K00-SCCW-8FEG-WUMY",
                    "OHQW-P968-50OC-9I9Q-WAJY-AKZB-C2AF",
                    "7CPS-TUQA-67QG-AMWI-TL8A-ISXN-B7XI",
                    "N8RK-03WN-G9QS-Q4N2-9DKO-FG74-WB5T",
                    "P0YM-ZUX2-R4C0-V72B-FPYP-W7P3-9VCK",
                    "7BHB-9KGY-G9RQ-G03I-9147-FI63-WINN",
                    "9D3N-WBAC-7SC6-OQUT-AV1R-T1EM-TM8E",
                    "3LSU-6P9F-93VU-CYX8-35GS-O6XP-9JFY",
                    "RUQ7-0NWR-FC57-X2W5-ZXA3-Q1ZR-H7S7",
                    "KODQ-OW4K-OSIK-MG59-QWU0-FIT6-6NCV",
                    "E7HN-1YGO-O3N9-PEP4-1ZBN-YJRM-O70N",
                    "LMW1-TOJ6-FH0W-J23H-HOXO-J1GJ-I8A6",
                    "83G4-BIIZ-JRDP-K3JJ-KXXN-YM86-KHCD",
                    "R3UG-A16R-GXVF-92GN-ZY3H-YGVD-5YTH",
                    "LV5N-6J9S-457A-VM0K-UK4K-YCXJ-8QDV",
                    "GKL3-KJ8Q-MFG8-SI8M-A18U-2267-QNDM",
                    "60QN-U57W-W105-N3FW-XZTF-QZ3X-PGBU",
                    "2QYB-NN13-EX7D-FLDQ-6PMU-1IJ6-COQX"));
        }

        public List<String> getTestList() {
            return testList;
        }
    }

    public static final Pattern REPLACE_PATTERN = Pattern.compile("_");

    private String replaceWithStringReplace(String string) {
        return string.replace("_", "");
    }

    private String replaceWithPattern(String string) {
        return REPLACE_PATTERN.matcher(string).replaceAll("");
    }

    @Benchmark
    @Fork(value = 1)
    @Warmup(iterations = 2)
    @Measurement(iterations = 2)
    public void usingStringReplace(InputClass inputClass, Blackhole bh) {
        for (String rs : inputClass.getTestList()) {
            bh.consume(replaceWithStringReplace(rs));
        }
    }

    @Benchmark
    @Fork(value = 1)
    @Warmup(iterations = 2)
    @Measurement(iterations = 2)
    public void usingCompiledPattern(InputClass inputClass, Blackhole bh) {
        for (String rs : inputClass.getTestList()) {
            bh.consume(replaceWithPattern(rs));
        }
    }

}

result

Benchmark                                                                Mode  Cnt        Score   Error   Units
ReplaceBenchmark.usingCompiledPattern                                   thrpt    2   143398.004           ops/s
ReplaceBenchmark.usingCompiledPattern:·gc.alloc.rate                    thrpt    2     1302.393          MB/sec
ReplaceBenchmark.usingCompiledPattern:·gc.alloc.rate.norm               thrpt    2    10001.038            B/op
ReplaceBenchmark.usingCompiledPattern:·gc.churn.G1_Eden_Space           thrpt    2     1306.088          MB/sec
ReplaceBenchmark.usingCompiledPattern:·gc.churn.G1_Eden_Space.norm      thrpt    2    10029.260            B/op
ReplaceBenchmark.usingCompiledPattern:·gc.churn.G1_Survivor_Space       thrpt    2        0.003          MB/sec
ReplaceBenchmark.usingCompiledPattern:·gc.churn.G1_Survivor_Space.norm  thrpt    2        0.022            B/op
ReplaceBenchmark.usingCompiledPattern:·gc.count                         thrpt    2      127.000          counts
ReplaceBenchmark.usingCompiledPattern:·gc.time                          thrpt    2       54.000              ms
ReplaceBenchmark.usingStringReplace                                     thrpt    2  1620601.122           ops/s
ReplaceBenchmark.usingStringReplace:·gc.alloc.rate                      thrpt    2       ≈ 10⁻⁴          MB/sec
ReplaceBenchmark.usingStringReplace:·gc.alloc.rate.norm                 thrpt    2       ≈ 10⁻⁵            B/op
ReplaceBenchmark.usingStringReplace:·gc.count                           thrpt    2          ≈ 0          counts