PerformanceUtil.java

public class PerformanceUtil {

    /*
    A utility to detect slow running functions
     */

    public static final int WARN_THRESHOLD_MILLIS =1000;

    public static <T> T timed(Executable<T> function) {

        long start = System.currentTimeMillis();
        try {
            return function.execute();
        } finally {
             long elapsed = System.currentTimeMillis() - start;
             if (elapsed > WARN_THRESHOLD_MILLIS) {
                 System.out.println("Method execution slow, took:" + elapsed + " ms.");
             }
        }
    }


    public interface Executable<T> {
        T execute();
    }

    public static void main(String args[]) {
        //example use case
        PerformanceUtil.timed(() -> Thread.getAllStackTraces().size());
    }
}