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vladimirdolzhenko/ClockGranularity.java

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PerfTiming
Raw
ClockGranularity.java
package com;
/*
MacOSX:
java 8
Benchmark Mode Cnt Score Error Units
ClockGranularity.granularityClockNanos avgt 2 999929.426 ns/op
ClockGranularity.granularityNanos avgt 2 41.420 ns/op
java 9
Benchmark Mode Cnt Score Error Units
ClockGranularity.granularityClockNanos avgt 2 1011,522 ns/op
ClockGranularity.granularityNanos avgt 2 41,657 ns/op
Windows:
java 9
Benchmark Mode Cnt Score Error Units
ClockGranularity.granularityClockNanos avgt 2 999916.218 ns/op
ClockGranularity.granularityNanos avgt 2 301.552 ns/op
Linux:
java 8
Benchmark Mode Cnt Score Error Units
ClockGranularity.granularityClockNanos avgt 2 999881.640 ns/op
ClockGranularity.granularityNanos avgt 2 42.009 ns/op
java 9
Benchmark Mode Cnt Score Error Units
ClockGranularity.granularityClockNanos avgt 2 1002.419 ns/op
ClockGranularity.granularityNanos avgt 2 43.195 ns/op
*/
import org.openjdk.jmh.annotations.*;
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;
import java.time.Clock;
import java.time.Instant;
import java.util.concurrent.TimeUnit;
/**
* @author vladimir.dolzhenko@gmail.com
* @since 2017-05-13
*/
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Fork(1)
@Warmup(iterations = 1, time = 15000, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 2, time = 15000, timeUnit = TimeUnit.MILLISECONDS)
@Threads(1)
@State(Scope.Benchmark)
public class ClockGranularity {
private long lastValue;
public static final Clock clock = Clock.systemUTC();
public static long clockNanos(){
final Instant instant = clock.instant();
return instant.getEpochSecond() * 1_000_000_000L + instant.getNano();
}
@Benchmark
public long granularityClockNanos() {
long cur;
do {
cur = clockNanos();
} while (cur == lastValue);
lastValue = cur;
return cur;
}
@Benchmark
public long granularityNanos() {
long cur;
do {
cur = System.nanoTime();
} while (cur == lastValue);
lastValue = cur;
return cur;
}
public static void main(String[] args) throws RunnerException {
Options opt = new OptionsBuilder()
.include(ClockGranularity.class.getSimpleName())
.build();
new Runner(opt).run();
}
}
Raw
com_PreciseTimestamp.c
/*
to compile on MacOsX:
$ gcc -dynamiclib -o libprecisetimestamp.dylib com_PreciseTimestamp.c -I$JAVA_HOME/include -I$JAVA_HOME/include/darwin -framework JavaVM
*/
#include <stdlib.h>
#include <sys/time.h>
#include <time.h>
#include <unistd.h>
#include "com_PreciseTimestamp.h"
JNIEXPORT jlong JNICALL Java_com_PreciseTimestamp_getMicros
(JNIEnv * env, jclass jc)
{
#if defined(_POSIX_TIMERS)
{
struct timespec ts;
if ( 0 == clock_gettime(CLOCK_REALTIME, &ts) )
{
return ((((jlong) ts.tv_sec) * 1000000) +
(((jlong) ts.tv_nsec)) / 1000);
}
}
#else
// otherwise use gettimeofday
struct timeval tv;
gettimeofday(&tv, NULL);
return (((jlong) tv.tv_sec) * 1000000) + ((jlong) tv.tv_usec);
#endif // _POSIX_TIMERS
}
JNIEXPORT jlong JNICALL Java_com_PreciseTimestamp_getCMicros
(JNIEnv * env, jclass jc)
{
#if defined(_POSIX_TIMERS)
{
struct timespec ts;
if ( 0 == clock_gettime(CLOCK_REALTIME, &ts) )
{
return ((((jlong) ts.tv_sec) * 1000000) +
(((jlong) ts.tv_nsec)) / 1000);
}
}
#else
// otherwise use gettimeofday
struct timeval tv;
gettimeofday(&tv, NULL);
return (((jlong) tv.tv_sec) * 1000000) + ((jlong) tv.tv_usec);
#endif
}
JNIEXPORT jlong JNICALL JavaCritical_com_PreciseTimestamp_getCMicros
()
{
#if defined(_POSIX_TIMERS)
{
struct timespec ts;
if ( 0 == clock_gettime(CLOCK_REALTIME, &ts) )
{
return ((((jlong) ts.tv_sec) * 1000000) +
(((jlong) ts.tv_nsec)) / 1000);
}
}
#else
// otherwise use gettimeofday
struct timeval tv;
gettimeofday(&tv, NULL);
return (((jlong) tv.tv_sec) * 1000000) + ((jlong) tv.tv_usec);
#endif
}
Raw
com_PreciseTimestamp.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_PreciseTimestamp */
#ifndef _Included_com_PreciseTimestamp
#define _Included_com_PreciseTimestamp
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com_PreciseTimestamp
* Method: getMicros
* Signature: ()J
*/
JNIEXPORT jlong JNICALL Java_com_PreciseTimestamp_getMicros
(JNIEnv *, jclass);
/*
* Class: com_PreciseTimestamp
* Method: getCMicros
* Signature: ()J
*/
JNIEXPORT jlong JNICALL Java_com_PreciseTimestamp_getCMicros
(JNIEnv *, jclass);
#ifdef __cplusplus
}
#endif
#endif
Raw
PerfTiming.java
package com;
/*
Benchmark Mode Cnt Score Error Units
PerfTiming.clockMicros avgt 5 60,452 ± 2,097 ns/op
PerfTiming.criticalJniMicros avgt 5 53,218 ± 1,220 ns/op
PerfTiming.instant avgt 5 62,082 ± 1,679 ns/op
PerfTiming.jniMicros avgt 5 54,001 ± 1,089 ns/op
PerfTiming.systemCurrentTimeMillis avgt 5 44,332 ± 0,625 ns/op
PerfTiming.systemNanoTime avgt 5 40,342 ± 1,322 ns/op
Benchmark Mode Cnt Score Error Units
PerfTiming.clockMicros avgt 5 60,832 ± 1,356 ns/op
PerfTiming.clockMicros:·gc.alloc.rate avgt 5 ≈ 10⁻⁵ MB/sec
PerfTiming.clockMicros:·gc.alloc.rate.norm avgt 5 ≈ 10⁻⁶ B/op
PerfTiming.clockMicros:·gc.count avgt 5 ≈ 0 counts
PerfTiming.instant avgt 5 67,714 ± 2,713 ns/op
PerfTiming.instant:·gc.alloc.rate avgt 5 327,083 ± 13,098 MB/sec
PerfTiming.instant:·gc.alloc.rate.norm avgt 5 24,000 ± 0,001 B/op
PerfTiming.instant:·gc.churn.CodeHeap_'non-profiled_nmethods' avgt 5 0,001 ± 0,001 MB/sec
PerfTiming.instant:·gc.churn.CodeHeap_'non-profiled_nmethods'.norm avgt 5 ≈ 10⁻⁴ B/op
PerfTiming.instant:·gc.churn.G1_Old_Gen avgt 5 327,390 ± 20,651 MB/sec
PerfTiming.instant:·gc.churn.G1_Old_Gen.norm avgt 5 24,021 ± 0,644 B/op
PerfTiming.instant:·gc.count avgt 5 167,000 counts
PerfTiming.instant:·gc.time avgt 5 102,000 ms
*/
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.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;
import java.time.Instant;
import java.util.concurrent.TimeUnit;
/**
* @author vladimir.dolzhenko@gmail.com
* @since 2017-05-09
*/
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Fork(1)
@Warmup(iterations = 3, time = 15000, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 5, time = 15000, timeUnit = TimeUnit.MILLISECONDS)
@Threads(1)
public class PerfTiming {
@Benchmark
public long systemNanoTime() {
return System.nanoTime();
}
@Benchmark
public long systemCurrentTimeMillis() {
return System.currentTimeMillis();
}
@Benchmark
public long jniMicros() {
return PreciseTimestamp.getMicros();
}
@Benchmark
public long criticalJniMicros() {
return PreciseTimestamp.getCMicros();
}
@Benchmark
public long clockMicros(){
return PreciseTimestamp.clockMicros();
}
@Benchmark
public Instant instant(){
return PreciseTimestamp.clock.instant();
}
public static void main(String[] args) throws RunnerException {
Options opt = new OptionsBuilder()
.addProfiler("gc")
.include(PerfTiming.class.getSimpleName())
.build();
new Runner(opt).run();
}
}
Raw
PreciseTimestamp.java
/*
java 8:
JNI micros: 1494398000506568
Critical JNI micros: 1494398000506986
ClockUTC micros: 1494398000507000
currentTimeMillis: 1494398000507
java 9:
JNI micros: 1494398039238236
Critical JNI micros: 1494398039238439
ClockUTC micros: 1494398039238498
currentTimeMillis: 1494398039239
*/
package com;
import java.time.Clock;
import java.time.Instant;
public final class PreciseTimestamp {
static {
try {
System.loadLibrary("precisetimestamp");
} catch (Throwable e){
throw new RuntimeException(e.getMessage(), e);
}
}
// JNI microsecond timestamp provider
public static native long getMicros();
// Critical JNI microsecond timestamp provider
public static native long getCMicros();
public static final Clock clock = Clock.systemUTC();
public static long clockMicros(){
final Instant instant = clock.instant();
return instant.getEpochSecond() * 1_000_000L + (instant.getNano() / 1_000);
}
public static void main(String[] args) {
System.out.println("JNI micros:\t\t\t\t" + PreciseTimestamp.getMicros());
System.out.println("Critical JNI micros:\t" + PreciseTimestamp.getCMicros());
System.out.println("ClockUTC micros:\t\t" + PreciseTimestamp.clockMicros());
System.out.println("currentTimeMillis:\t\t" + System.currentTimeMillis());
}
}
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