Calculate Code Execution Time in Spring Boot

Calculate Code Execution Time in Spring Boot | To calculate code execution time in Spring Boot we can use the StopWatch class. This is a class given by Spring F/w in org.springframework.util package to calculate the time taken for task/block/method/object creation etc. Methods:-

• start(): It will start time counting
• start(taskName):- Start time counting and assign task name
• stop(): It will stop time counting
• getTotalTimeMillis(): return long
• getTotalTimeSeconds(): return int
• prettyPrint(): return String

Time Factor Scale:-

• NANO_SCALE = 1L;
• MICRO_SCALE = 1000L * NANO_SCALE;
• MILLI_SCALE = 1000L * MICRO_SCALE;
• SECOND_SCALE = 1000L * MILLI_SCALE;
• MINUTE_SCALE = 60L * SECOND_SCALE;
• HOUR_SCALE = 60L * MINUTE_SCALE;
• DAY_SCALE = 24L * HOUR_SCALE;

How to use the stopwatch:-

StopWatch stopWatch = new StopWatch();
stopWatch.start();
// code 
stopWatch.stop();
System.out.println(stopWatch.getTotalTimeMillis());

Example:-

package com.knowprogram.demo;

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import org.springframework.util.StopWatch;

@Component
public class TimeTestRunner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        StopWatch stopWatch = new StopWatch();
        stopWatch.start();
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            Math.sqrt(i);
        }
        stopWatch.stop();
        System.out.println("Total time in milli seconds: " 
                + stopWatch.getTotalTimeMillis());
        System.out.println("Total time in seconds: " 
                + stopWatch.getTotalTimeSeconds());
    }

}

Output:-

Total time in milli seconds: 519
Total time in seconds: 0.5191696

Assume we have 3 parts of the code and we want to calculate execution time only for 1st and 3rd parts then we can use stop() and again() to resume the calculation.

package com.knowprogram.demo;

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;
import org.springframework.util.StopWatch;

@Component
public class TimeTestRunner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        StopWatch watch = new StopWatch("Time Test For Loops"); // Watch#ID
        watch.start("Loop#1"); // Watch#taskName
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            Math.sqrt(i);
            Math.pow(i + 1, 1000);
        }
        watch.stop();

        // skip this part
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            Math.sqrt(i);
        }

        watch.start("Loop#2");
        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            Math.sqrt(i);
        }
        watch.stop();

        System.out.println(watch.prettyPrint());
    }

}

Output:-

StopWatch 'Time Test For Loops': 1.5267636 seconds
--------------------------------------------------
Seconds       %       Task name
--------------------------------------------------
0.5137293     34%     Loop#1
1.0130343     66%     Loop#2

IllegalStateException while Using StopWatch

We can’t start the StopWatch which is already running, first we have to stop it. Similarly, we can’t stop the StopWatch which is running stopped.

watch.stop(); // watch stopped
watch.stop(); // exception

IllegalStateException: Can’t stop StopWatch: it’s not running.

watch.start(); // watch started
watch.start(); // exception

IllegalStateException: Can’t start StopWatch: it’s already running.

TimeUnit

While working with StopWatch For time conversion we can use the TimeUnit class of java.util.concurrent package.

package com.knowprogram.demo;

import java.util.concurrent.TimeUnit;

import org.springframework.boot.CommandLineRunner;
import org.springframework.stereotype.Component;

@Component
public class TimeTestRunner implements CommandLineRunner {

    @Override
    public void run(String... args) throws Exception {
        // 3 days-> hours
        System.out.println(TimeUnit.DAYS.toHours(3));
        // 3 days-> mins
        System.out.println(TimeUnit.DAYS.toMinutes(3));
        // 1 sec-> nano sec
        System.out.println(TimeUnit.SECONDS.toNanos(1));
        // 10 min-> mill sec
        System.out.println(TimeUnit.MINUTES.toMillis(10));
    }

}

Output:-

72
4320
1000000000
600000

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