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JMH使用案例-日期格式化工具性能对比

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一、背景

最近在看代码，发现一个 Date 格式化为 String 的方法。

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public String dateFormatString() {
    return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(date);
}

看到这个方法想到

  • 每次都 new 一个 format 会快么(非线程安全，得每次都 new)？
  • SimpleDateFormat 格式化快么？
  • “yyyy-MM-dd HH:mm:ss.SSS” 改成静态常量会不会快点？

带着以上三个疑问，就想着做个对比测试。
恰巧最近在 perfma 社区看 jvm 相关内容时，刷到了『性能调优必备利器之 JMH』

优点：不用自己写相关统计代码，而且统计方式有多种

二、结论

性能从低到高

  • java.text.SimpleDateFormat
  • org.apache.commons.lang.time.DateFormatUtils
  • org.joda.time.DateTime

字符串静态常量影响

  • 是否静态常量几乎没有影响
  • 使用常量反而性能有所下降(???为何)
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Benchmark                                             Mode  Cnt        Score        Error  Units
DateConvertTest.dateFormatString                     thrpt   10   867333.631 ±   9510.553  ops/s
DateConvertTest.dateFormatStringApache               thrpt   10  2158217.955 ±  89012.866  ops/s
DateConvertTest.dateFormatStringApacheStaticPattern  thrpt   10  2141167.550 ±  93715.889  ops/s
DateConvertTest.dateFormatStringJoda                 thrpt   10  2802803.925 ± 121600.833  ops/s
DateConvertTest.dateFormatStringJodaStaticPattern    thrpt   10  2744918.391 ± 131925.235  ops/s

说明：
Error 列是空的，看 Score 和 Units 即可
ops/s:一秒钟执行多少次操作

三、代码

3.1 引入相关 jar

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<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-core</artifactId>
    <version>1.23</version>
</dependency>
<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-generator-annprocess</artifactId>
    <version>1.23</version>
</dependency>

3.2 IDEA 安装 JMH 插件

插件中心搜索：JMH
安装量最高的那个就是

3.3 编写代码

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import org.apache.commons.lang.time.DateFormatUtils;
import org.joda.time.DateTime;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * @author hisenyuan
 * @date 2021/5/10 18:39
 */
// 默认的 State，每个测试线程分配一个实例
@State(Scope.Thread)
// 如果 fork 数是 2 的话，则 JMH 会 fork 出两个进程来进行测试。
@Fork(1)
// 预热的次数 3 次基准测试(不是执行三次方法)
@Warmup(iterations = 3)
// 基准执行次数 10 次(参数含义同上)
@Measurement(iterations = 10)
public class DateConvertTest {
    private final static Date date = new Date();
    private final static String PATTERN = "yyyy-MM-dd HH:mm:ss.SSS";

    @Benchmark
    public String dateFormatString() {
        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS").format(date);
    }

    @Benchmark
    public String dateFormatStringJoda() {
        return new DateTime(date).toString("yyyy-MM-dd HH:mm:ss.SSS");
    }

    @Benchmark
    public String dateFormatStringJodaStaticPattern() {
        return new DateTime(date).toString(PATTERN);
    }

    @Benchmark
    public String dateFormatStringApache() {
        return DateFormatUtils.format(date, "yyyy-MM-dd HH:mm:ss.SSS");
    }

    @Benchmark
    public String dateFormatStringApacheStaticPattern() {
        return DateFormatUtils.format(date, PATTERN);
    }
}

3.4 执行

安装了 JMH 插件之后，直接对着类名右键，选择运行即可。
JMH 会默认执行当前类下面的所有的基准测试。

四、执行结果

ETA 00:10:50 代表整个测试需要近11分钟

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# JMH version: 1.23
# VM version: JDK 1.8.0_171, Java HotSpot(TM) 64-Bit Server VM, 25.171-b11
# VM invoker: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre/bin/java
# VM options: -Dfile.encoding=UTF-8
# Warmup: 3 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatString

# Run progress: 0.00% complete, ETA 00:10:50
# Fork: 1 of 1
# Warmup Iteration   1: 698627.190 ops/s
# Warmup Iteration   2: 873835.360 ops/s
# Warmup Iteration   3: 870972.646 ops/s
Iteration   1: 875650.632 ops/s
Iteration   2: 872407.599 ops/s
Iteration   3: 864390.061 ops/s
Iteration   4: 872456.756 ops/s
Iteration   5: 870538.248 ops/s
Iteration   6: 861600.599 ops/s
Iteration   7: 868469.312 ops/s
Iteration   8: 868930.572 ops/s
Iteration   9: 864686.616 ops/s
Iteration  10: 854205.911 ops/s


Result "com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatString":
  867333.631 ±(99.9%) 9510.553 ops/s [Average]
  (min, avg, max) = (854205.911, 867333.631, 875650.632), stdev = 6290.642
  CI (99.9%): [857823.077, 876844.184] (assumes normal distribution)


# JMH version: 1.23
# VM version: JDK 1.8.0_171, Java HotSpot(TM) 64-Bit Server VM, 25.171-b11
# VM invoker: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre/bin/java
# VM options: -Dfile.encoding=UTF-8
# Warmup: 3 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringApache

# Run progress: 20.00% complete, ETA 00:08:42
# Fork: 1 of 1
# Warmup Iteration   1: 1922497.366 ops/s
# Warmup Iteration   2: 2121425.254 ops/s
# Warmup Iteration   3: 2142439.041 ops/s
Iteration   1: 2174791.808 ops/s
Iteration   2: 2101868.007 ops/s
Iteration   3: 2174003.026 ops/s
Iteration   4: 2202522.277 ops/s
Iteration   5: 2039234.570 ops/s
Iteration   6: 2105338.449 ops/s
Iteration   7: 2205933.974 ops/s
Iteration   8: 2175865.041 ops/s
Iteration   9: 2167544.736 ops/s
Iteration  10: 2235077.658 ops/s


Result "com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringApache":
  2158217.955 ±(99.9%) 89012.866 ops/s [Average]
  (min, avg, max) = (2039234.570, 2158217.955, 2235077.658), stdev = 58876.499
  CI (99.9%): [2069205.089, 2247230.821] (assumes normal distribution)


# JMH version: 1.23
# VM version: JDK 1.8.0_171, Java HotSpot(TM) 64-Bit Server VM, 25.171-b11
# VM invoker: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre/bin/java
# VM options: -Dfile.encoding=UTF-8
# Warmup: 3 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringApacheStaticPattern

# Run progress: 40.00% complete, ETA 00:06:31
# Fork: 1 of 1
# Warmup Iteration   1: 1964208.975 ops/s
# Warmup Iteration   2: 2138997.654 ops/s
# Warmup Iteration   3: 2164194.409 ops/s
Iteration   1: 2221565.433 ops/s
Iteration   2: 2231776.725 ops/s
Iteration   3: 2210494.794 ops/s
Iteration   4: 2057487.199 ops/s
Iteration   5: 2111366.133 ops/s
Iteration   6: 2150355.985 ops/s
Iteration   7: 2116673.562 ops/s
Iteration   8: 2140376.847 ops/s
Iteration   9: 2099801.246 ops/s
Iteration  10: 2071777.579 ops/s


Result "com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringApacheStaticPattern":
  2141167.550 ±(99.9%) 93715.889 ops/s [Average]
  (min, avg, max) = (2057487.199, 2141167.550, 2231776.725), stdev = 61987.258
  CI (99.9%): [2047451.661, 2234883.440] (assumes normal distribution)


# JMH version: 1.23
# VM version: JDK 1.8.0_171, Java HotSpot(TM) 64-Bit Server VM, 25.171-b11
# VM invoker: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre/bin/java
# VM options: -Dfile.encoding=UTF-8
# Warmup: 3 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringJoda

# Run progress: 60.00% complete, ETA 00:04:21
# Fork: 1 of 1
# Warmup Iteration   1: 2767967.530 ops/s
# Warmup Iteration   2: 2839342.269 ops/s
# Warmup Iteration   3: 2824726.959 ops/s
Iteration   1: 2859527.645 ops/s
Iteration   2: 2799624.402 ops/s
Iteration   3: 2876558.678 ops/s
Iteration   4: 2862478.579 ops/s
Iteration   5: 2882872.177 ops/s
Iteration   6: 2860788.081 ops/s
Iteration   7: 2742885.180 ops/s
Iteration   8: 2779727.212 ops/s
Iteration   9: 2719266.181 ops/s
Iteration  10: 2644311.112 ops/s


Result "com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringJoda":
  2802803.925 ±(99.9%) 121600.833 ops/s [Average]
  (min, avg, max) = (2644311.112, 2802803.925, 2882872.177), stdev = 80431.422
  CI (99.9%): [2681203.092, 2924404.757] (assumes normal distribution)


# JMH version: 1.23
# VM version: JDK 1.8.0_171, Java HotSpot(TM) 64-Bit Server VM, 25.171-b11
# VM invoker: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre/bin/java
# VM options: -Dfile.encoding=UTF-8
# Warmup: 3 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Throughput, ops/time
# Benchmark: com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringJodaStaticPattern

# Run progress: 80.00% complete, ETA 00:02:10
# Fork: 1 of 1
# Warmup Iteration   1: 2711358.480 ops/s
# Warmup Iteration   2: 2823432.725 ops/s
# Warmup Iteration   3: 2745545.759 ops/s
Iteration   1: 2752446.099 ops/s
Iteration   2: 2792047.450 ops/s
Iteration   3: 2828389.094 ops/s
Iteration   4: 2799921.909 ops/s
Iteration   5: 2670924.332 ops/s
Iteration   6: 2533779.871 ops/s
Iteration   7: 2733321.639 ops/s
Iteration   8: 2738839.592 ops/s
Iteration   9: 2802775.869 ops/s
Iteration  10: 2796738.055 ops/s


Result "com.jd.finance.jrpaypassword.performance.DateConvertTest.dateFormatStringJodaStaticPattern":
  2744918.391 ±(99.9%) 131925.235 ops/s [Average]
  (min, avg, max) = (2533779.871, 2744918.391, 2828389.094), stdev = 87260.375
  CI (99.9%): [2612993.156, 2876843.626] (assumes normal distribution)


# Run complete. Total time: 00:10:52

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.

Benchmark                                             Mode  Cnt        Score        Error  Units
DateConvertTest.dateFormatString                     thrpt   10   867333.631 ±   9510.553  ops/s
DateConvertTest.dateFormatStringApache               thrpt   10  2158217.955 ±  89012.866  ops/s
DateConvertTest.dateFormatStringApacheStaticPattern  thrpt   10  2141167.550 ±  93715.889  ops/s
DateConvertTest.dateFormatStringJoda                 thrpt   10  2802803.925 ± 121600.833  ops/s
DateConvertTest.dateFormatStringJodaStaticPattern    thrpt   10  2744918.391 ± 131925.235  ops/s

五、JMH 介绍