[GitHub] [systemml] xtern edited a comment on issue #862: Systemml 2526 Date.getTime() can be changed to System.currentTimeMillis()

[GitBox <gi...@apache.org>]

xtern edited a comment on issue #862: Systemml 2526 Date.getTime() can be changed to System.currentTimeMillis()
URL: https://github.com/apache/systemml/pull/862#issuecomment-483341237
 
 
   > Hello, please see the example program.
   
   Hello! I was a little confused with your benchmarking and re-checked these results with JMH on Ubuntu (jdk8) and found that the difference is not that significant: currentTimeMillis faster for 0.02 nanosecond per operation (less than the measurement error).
   Anyway I think It's much better to use currentTimeMillis instead of new Date().getTime()
   ```
   Benchmark             Mode  Cnt   Score   Error  Units
   TimeTest.checkDate    avgt   10  22.733 ± 0.106  ns/op
   TimeTest.checkMillis  avgt   10  22.753 ± 0.106  ns/op
   ```
   code
   ```java
   import java.util.Date;
   import java.util.concurrent.TimeUnit;
   import org.openjdk.jmh.annotations.Benchmark;
   import org.openjdk.jmh.annotations.BenchmarkMode;
   import org.openjdk.jmh.annotations.Fork;
   import org.openjdk.jmh.annotations.Measurement;
   import org.openjdk.jmh.annotations.Mode;
   import org.openjdk.jmh.annotations.OutputTimeUnit;
   import org.openjdk.jmh.annotations.Scope;
   import org.openjdk.jmh.annotations.State;
   import org.openjdk.jmh.annotations.Threads;
   import org.openjdk.jmh.annotations.Warmup;
   import org.openjdk.jmh.runner.Runner;
   import org.openjdk.jmh.runner.RunnerException;
   import org.openjdk.jmh.runner.options.Options;
   import org.openjdk.jmh.runner.options.OptionsBuilder;
   
   @BenchmarkMode(Mode.AverageTime)
   @Fork(value = 1, jvmArgsAppend = {"-Xms3g", "-Xmx3g", "-server", "-XX:+AggressiveOpts"})
   @OutputTimeUnit(TimeUnit.NANOSECONDS)
   @State(Scope.Benchmark)
   @Threads(1)
   @Warmup(iterations = 10)
   @Measurement(iterations = 20)
   public class TimeTest {
       @Benchmark
       public long checkDate() {
           return new Date().getTime();
       }
   
       @Benchmark
       public long checkMillis() {
           return System.currentTimeMillis();
       }
   
       public static void main(String[] args) throws RunnerException {
           final Options options = new OptionsBuilder()
               .include(TimeTest.class.getSimpleName())
               .build();
   
           new Runner(options).run();
       }
   }
   ```

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