如何计算Java服务所花费的总时间？

Question

I'm running a simple java program using multithreading. Each thread calls a service. I want to print the total time taken for a service call. Please advise how to do this in multithreading environment. My code as shown below is not giving the proper result. Please help.

public class ServiceCaller {
    private long totalTime;

    public void makeRequest() {
        long startTime = System.currentTimeMillis();
        serviceCall()
        long endTime = System.currentTimeMillis();
        totalTime = totalTime+(endTime-startTime);
        System.out.println(DurationFormatUtils.formatDurationHMS(totalTime))
    }
}

Answer 1

Access to totalTime should be synchronized and volatile . Without syncronisation different threads will be writing over the value. Without volatile different threads could see different values. You can simplify the access by using the wrapper classes such as AtomicLong .

Depending on the platform you are using you may be able to avoid polluting your service class with unrelated timing code with AOP. Most DI frameworks (include Guice and Spring ) support this.

Answer 2

Access to totalTime should be thread safe. You can use an AtomicLong

final AtomicLong timeTaken = new AtomicLong(0);

// later
timeTaken.addAndGet(endTime - startTime);

You might like to use System.nanoTime() instead of System.currentTimeMillis() for greater resolution.