8.10. Estimating the Amount of Time Left in a Process
Problem
You are running a program that takes a long time to execute, and you need to present the user with an estimated time until completion.
Solution
Use Commons Math’s
SimpleRegression
and Commons Lang’s StopWatch to
create a
ProcessEstimator
class that can be used to predict when a
particular program will be finished. Your program needs to process a
number of records, and this program could take a few hours to finish.
You would like to provide some feedback, and, if you are confident
that each record will take roughly the same amount of time, you can
use SimpleRegression’s slope and
intercept to estimate the time when all records will be processed.
Example 8-1 defines the
ProcessEstimator class that combines the power of
StopWatch and ProcessEstimator
to estimate the time remaining in a process.
Example 8-1. ProcessEstimator to estimate time of program execution
package com.discursive.jccook.math.timeestimate; import org.apache.commons.lang.time.StopWatch; import org.apache.commons.math.stat.multivariate.SimpleRegression; public class ProcessEstimator { private SimpleRegression regression = new SimpleRegression( ); private StopWatch stopWatch = new StopWatch( ); // Total number of units private int units = 0; // Number of units completed private int completed = 0; // Sample rate for regression private int sampleRate = 1; public ProcessEstimator( int numUnits, int sampleRate ) { this.units = numUnits; this.sampleRate = sampleRate; ...Get Jakarta Commons Cookbook now with the O’Reilly learning platform.
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