how to minimize the execution time for a java program?

Question

I have created a program in java for entering 1000 random numbers into two different database one for odd numbers and one for even. The code is executing fine but it takes nearly a minute to execute. How can I minimize the Execution time?

Here is the code:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Random;

public class Test1 extends Thread {

public static void main(String[] args) throws ClassNotFoundException, SQLException {
    long start = System.currentTimeMillis();

    int evencount = 0;
    int oddcount = 0;
    int breakcon = 0;
    int breakcon1 = 0;

    Class.forName("com.mysql.jdbc.Driver");
    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1" + "?useSSL=false", "root",
            "1234");
    Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/db2" + "?useSSL=false", "root",
            "1234");

    try {

        Class.forName("com.mysql.jdbc.Driver");

        for (int n = 1; n <= 1000; n++) {
            Random r = new Random();
            int val = r.nextInt(100000);

            if (val % 2 == 0) {
                PreparedStatement ps = con.prepareStatement(" insert into try values (?)");
                ps.setInt(1, val);
                ps.executeUpdate();
                ps.addBatch();
                breakcon = breakcon + 1;
                if (breakcon % 500 == 0 || breakcon == val)
                    ps.executeBatch();
                evencount++;

            } else {
                try {

                    Class.forName("com.mysql.jdbc.Driver");
                    PreparedStatement ps3 = conn.prepareStatement(" insert into try1 values (?)");
                    ps3.setInt(1, val);
                    ps3.executeUpdate();
                    ps3.addBatch();
                    breakcon1 = breakcon1 + 1;
                    if (breakcon1 % 500 == 0 || breakcon1 == val)
                        ps3.executeBatch();

                    oddcount++;

                }

                catch (Exception e2) {
                    System.out.println(e2);
                }
            }
        }

    }

    catch (Exception e) {
        System.out.println(e);
    }

    long end = System.currentTimeMillis();
    NumberFormat formatter = new DecimalFormat("#0.00000");
    System.out.println("Execution time is " + formatter.format((end - start) / 1000d) + " seconds");
    System.out.println(oddcount + evencount);

}
}

These Kind of questions is better asks at [codereview.SE]. Because it is about improving running code — Jens, Sep 05 '17 at 06:29
Possible duplicate of [Efficient way to do batch INSERTS with JDBC](https://stackoverflow.com/questions/3784197/efficient-way-to-do-batch-inserts-with-jdbc) — Joe C, Sep 05 '17 at 06:29
Hint: if you need to copy and paste the same text twice to get over question restrictions **you are asking a bad question**. It will get downvoted and closed. Post output from a profiler. Describe _where_ your code is slow. Describe how fast you _need_ it to be? I reckon this could be done in a couple hundred millis with batching and one thread for each type of number. — Boris the Spider, Sep 05 '17 at 06:30
@Jens rather remove `Class.forName()` completely... that's a real blast from the past. — Kayaman, Sep 05 '17 at 06:35
Change Random random = new Random to ThreadLocalRandom.current(). It has better performance. — egorlitvinenko, Sep 05 '17 at 08:23

Nir Alfasi · Answer 1 · 2017-09-05T06:40:29.690

2

Instead of calling ps.executeUpdate(); (and ps3.executeUpdate();) after each time you setInt - do it only once after the for-loop. That's the whole point of using addBatch (aggregate inserts/updates and executing them all at once).

As Boris mentioned in the comment below, it would make the execution much faster if you also turn on rewriteBatchedStatements. See here how it can be achieved.

edited Sep 05 '17 at 06:40

answered Sep 05 '17 at 06:34

Nir Alfasi

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I guess turning on `rewriteBatchedStatements` would help too? – Boris the Spider Sep 05 '17 at 06:37
@BoristheSpider good point, thanks! – Nir Alfasi Sep 05 '17 at 06:40

how to minimize the execution time for a java program?

1 Answers1