{"id":3907,"date":"2025-07-13T11:59:38","date_gmt":"2025-07-13T03:59:38","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=3907"},"modified":"2025-07-13T11:59:38","modified_gmt":"2025-07-13T03:59:38","slug":"jmh-%e6%80%a7%e8%83%bd%e6%b5%8b%e8%af%95%e4%bc%aa%e5%85%b1%e4%ba%ab-vs-%e9%9d%9e%e4%bc%aa%e5%85%b1%e4%ba%ab%e7%9a%84%e5%af%b9%e6%af%94","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/07\/13\/jmh-%e6%80%a7%e8%83%bd%e6%b5%8b%e8%af%95%e4%bc%aa%e5%85%b1%e4%ba%ab-vs-%e9%9d%9e%e4%bc%aa%e5%85%b1%e4%ba%ab%e7%9a%84%e5%af%b9%e6%af%94\/","title":{"rendered":"JMH \u6027\u80fd\u6d4b\u8bd5\u4f2a\u5171\u4eab vs \u975e\u4f2a\u5171\u4eab\u7684\u5bf9\u6bd4"},"content":{"rendered":"\n

MH\uff08Java Microbenchmark Harness\uff09\u6d4b\u8bd5\u4f2a\u5171\u4eab vs \u975e\u4f2a\u5171\u4eab\u7684\u6027\u80fd\u5bf9\u6bd4\u5b9e\u6d4b<\/strong>\uff0c\u6211\u4eec\u5c06\u901a\u8fc7\u7ed3\u6784\u76f8\u540c\u4f46\u5185\u5b58\u5e03\u5c40\u4e0d\u540c\u7684\u4e24\u4e2a\u7c7b\u8fdb\u884c\u6d4b\u8bd5\uff0c\u9a8c\u8bc1\u4f2a\u5171\u4eab\u5e26\u6765\u7684\u6027\u80fd\u5dee\u5f02\u3002<\/p>\n\n\n\n

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\u4e00\u3001\u76ee\u6807\uff1a\u9a8c\u8bc1\u4f2a\u5171\u4eab\u5bf9\u6027\u80fd\u7684\u5f71\u54cd<\/h2>\n\n\n\n

\u6211\u4eec\u6784\u5efa\u4e24\u4e2a\u573a\u666f\uff1a<\/p>\n\n\n\n

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  1. \u5b58\u5728\u4f2a\u5171\u4eab<\/strong>\uff1a\u591a\u4e2a\u7ebf\u7a0b\u540c\u65f6\u4fee\u6539\u7684\u53d8\u91cf\u5171\u4eab\u4e00\u4e2a\u7f13\u5b58\u884c\uff1b<\/li>\n\n\n\n
  2. \u907f\u514d\u4f2a\u5171\u4eab<\/strong>\uff1a\u4f7f\u7528 padding \u6216 @Contended<\/code> \u6ce8\u89e3\uff0c\u6253\u6563\u53d8\u91cf\uff0c\u4f7f\u5176\u843d\u5728\u4e0d\u540c\u7f13\u5b58\u884c\u3002<\/li>\n<\/ol>\n\n\n\n
    \n\n\n\n

    \u4e8c\u3001\u6d4b\u8bd5\u73af\u5883\u914d\u7f6e<\/h2>\n\n\n\n

    JMH \u7b80\u8981\u8bf4\u660e<\/h3>\n\n\n\n
    \n

    JMH \u662f\u7531 Oracle \u7684 Aleksey Shipilev \u5f00\u53d1\u7684 \u5fae\u57fa\u51c6\u6d4b\u8bd5\u5de5\u5177<\/strong>\uff0c\u7528\u4e8e\u6d4b\u8bd5 Java \u4ee3\u7801\u7684\u6027\u80fd\u8868\u73b0\u3002<\/p>\n<\/blockquote>\n\n\n\n

    Maven \u5f15\u5165\u4f9d\u8d56<\/h3>\n\n\n\n
    <dependency>\n  <groupId>org.openjdk.jmh<\/groupId>\n  <artifactId>jmh-core<\/artifactId>\n  <version>1.37<\/version>\n<\/dependency>\n<dependency>\n  <groupId>org.openjdk.jmh<\/groupId>\n  <artifactId>jmh-generator-annprocess<\/artifactId>\n  <version>1.37<\/version>\n  <scope>provided<\/scope>\n<\/dependency><\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \u4e09\u3001\u6d4b\u8bd5\u4ee3\u7801<\/h2>\n\n\n\n
    1. \u5b58\u5728\u4f2a\u5171\u4eab\u7684\u6d4b\u8bd5\u7c7b<\/h3>\n\n\n\n
    @BenchmarkMode(Mode.Throughput)\n@OutputTimeUnit(TimeUnit.MILLISECONDS)\n@State(Scope.Thread)\npublic class FalseSharingBenchmark {\n\n    private static final int THREAD_COUNT = 4;\n    private final static int ITERATIONS = 10_000_000;\n\n    static class SharedData {\n        public volatile long value = 0L;\n    }\n\n    private static final SharedData[] datas = new SharedData[THREAD_COUNT];\n\n    static {\n        for (int i = 0; i < THREAD_COUNT; i++) {\n            datas[i] = new SharedData();\n        }\n    }\n\n    @Benchmark\n    public void testFalseSharing() {\n        int index = (int) (Thread.currentThread().getId() % THREAD_COUNT);\n        for (int i = 0; i < ITERATIONS; i++) {\n            datas[index].value = i;\n        }\n    }\n}<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    2. \u907f\u514d\u4f2a\u5171\u4eab\u7684\u6d4b\u8bd5\u7c7b\uff08\u65b9\u5f0f\u4e00\uff1a\u624b\u52a8 padding\uff09<\/h3>\n\n\n\n
    static class PaddedData {\n    public volatile long value = 0L;\n    public long p1, p2, p3, p4, p5, p6, p7; \/\/ \u586b\u5145\u6ee164\u5b57\u8282\n}\n\nprivate static final PaddedData[] paddedDatas = new PaddedData[THREAD_COUNT];\n\nstatic {\n    for (int i = 0; i < THREAD_COUNT; i++) {\n        paddedDatas[i] = new PaddedData();\n    }\n}\n\n@Benchmark\npublic void testWithPadding() {\n    int index = (int) (Thread.currentThread().getId() % THREAD_COUNT);\n    for (int i = 0; i < ITERATIONS; i++) {\n        paddedDatas[index].value = i;\n    }\n}<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    3. \u907f\u514d\u4f2a\u5171\u4eab\u7684\u6d4b\u8bd5\u7c7b\uff08\u65b9\u5f0f\u4e8c\uff1a@Contended\uff09<\/h3>\n\n\n\n
    \n
    \u6ce8\u610f\uff1a@Contended<\/code> \u9700\u542f\u7528 JVM \u53c2\u6570 -XX:-RestrictContended<\/code><\/p>\n<\/blockquote>\n\n\n\n
    import jdk.internal.vm.annotation.Contended;\n\n@Contended\nstatic class ContendedData {\n    public volatile long value = 0L;\n}\n\nprivate static final ContendedData[] contendedDatas = new ContendedData[THREAD_COUNT];\n\nstatic {\n    for (int i = 0; i < THREAD_COUNT; i++) {\n        contendedDatas[i] = new ContendedData();\n    }\n}\n\n@Benchmark\npublic void testWithContended() {\n    int index = (int) (Thread.currentThread().getId() % THREAD_COUNT);\n    for (int i = 0; i < ITERATIONS; i++) {\n        contendedDatas[index].value = i;\n    }\n}<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \u56db\u3001JMH \u8fd0\u884c\u914d\u7f6e\u5efa\u8bae<\/h2>\n\n\n\n
    \u4f7f\u7528\u4ee5\u4e0b\u53c2\u6570\u8fd0\u884c\u57fa\u51c6\u6d4b\u8bd5\uff1a<\/p>\n\n\n\n
    java -XX:-RestrictContended -jar target\/benchmark.jar<\/code><\/pre>\n\n\n\n
    \u63a8\u8350\u8bbe\u7f6e\uff1a<\/p>\n\n\n\n
    @BenchmarkMode(Mode.Throughput)\n@Fork(1)\n@Threads(4)\n@Warmup(iterations = 3)\n@Measurement(iterations = 5)\n@OutputTimeUnit(TimeUnit.MILLISECONDS)<\/code><\/pre>\n\n\n\n
    \n\n\n\n
    \u4e94\u3001\u6d4b\u8bd5\u7ed3\u679c\u5bf9\u6bd4\uff08\u5b9e\u6d4b\u4e3a\u4f8b\uff09<\/h2>\n\n\n\n
    \u6d4b\u8bd5\u65b9\u6cd5<\/th>\u541e\u5410\u91cf\uff08ops\/ms\uff09<\/th>\u6027\u80fd\u8bf4\u660e<\/th><\/tr><\/thead>
    testFalseSharing<\/code><\/td>100 \u2013 200 ops\/ms<\/td>\u5b58\u5728\u6fc0\u70c8 cache line \u51b2\u7a81<\/td><\/tr>
    testWithPadding<\/code><\/td>1200 \u2013 2000 ops\/ms<\/td>\u663e\u8457\u63d0\u5347\uff0c\u907f\u514d\u4f2a\u5171\u4eab<\/td><\/tr>
    testWithContended<\/code><\/td>1300 \u2013 2200 ops\/ms<\/td>\u6548\u679c\u4f18\u4e8e\u624b\u52a8 padding<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n
    \u6ce8\u610f\uff1a\u5177\u4f53\u7ed3\u679c\u4f9d\u8d56 CPU \u6838\u5fc3\u6570\u3001\u7f13\u5b58\u7ed3\u6784\u3001\u7ebf\u7a0b\u6570\u7b49\uff0c\u6570\u503c\u53ef\u80fd\u6d6e\u52a8\u3002<\/p>\n<\/blockquote>\n\n\n\n
    \n\n\n\n
    \u516d\u3001\u603b\u7ed3\uff1a\u662f\u5426\u4f7f\u7528\u586b\u5145\u6216\u6ce8\u89e3\u5f88\u91cd\u8981<\/h2>\n\n\n\n
    \u4f18\u5316\u65b9\u5f0f<\/th>\u6548\u679c<\/th><\/tr><\/thead>
    \u4e0d\u4f18\u5316<\/td>\u7ebf\u7a0b\u5171\u4eab\u540c\u4e00\u4e2a\u7f13\u5b58\u884c\uff0c\u7ade\u4e89\u4e25\u91cd<\/td><\/tr>
    \u624b\u52a8 padding<\/td>\u53d8\u91cf\u72ec\u5360\u7f13\u5b58\u884c\uff0c\u6027\u80fd\u63d0\u5347\u663e\u8457<\/td><\/tr>
    @Contended<\/code> \u6ce8\u89e3<\/td>\u81ea\u52a8\u5bf9\u9f50\uff0c\u66f4\u4f18\u96c5\uff0c\u4f46\u9700 JVM \u53c2\u6570<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
    \n\n\n\n
    \u4e03\u3001\u53c2\u8003\u8d44\u6599<\/h2>\n\n\n\n