import java.sql.*;
import java.util.Properties;
import java.util.concurrent.*;

public class Sample {
    private static final String dbClassName = "com.mysql.jdbc.Driver";
    private static final String CONNECTION = "jdbc:mysql://127.0.0.1:3306/";
    private static final String USER = "root";
    private static final String PASSWORD = "";
    private static void executeSQL(Connection conn, String sql) throws SQLException {
        try (Statement stmt = conn.createStatement()) {
            stmt.execute(sql);
        }
    }
    private static void ResetEnvironment() throws SQLException {
        Properties p = new Properties();
        p.put("user", USER);
        p.put("password", PASSWORD);
        try (Connection conn = DriverManager.getConnection(CONNECTION, p)) {
            for (String query: new String[] {
                    "DROP DATABASE IF EXISTS test",
                    "CREATE DATABASE test",
                    "USE test",
                    "CREATE TABLE tbl (id INT AUTO_INCREMENT PRIMARY KEY)"
            }) {
                executeSQL(conn, query);
            }
        }
    }
    private static void worker() {
        Properties properties = new Properties();
        properties.put("user", USER);
        properties.put("password", PASSWORD);
        try (Connection conn = DriverManager.getConnection(CONNECTION, properties)) {
            executeSQL(conn, "USE test");
            while (!Thread.interrupted()) {
                executeSQL(conn, "INSERT INTO tbl VALUES (NULL)");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) throws ClassNotFoundException, SQLException, InterruptedException {
        Class.forName(dbClassName);
        ResetEnvironment();
        ExecutorService executor = Executors.newFixedThreadPool(20);
        for (int i = 0; i < 20; i++) {
            executor.submit(new Runnable() {
                @Override
                public void run() {
                    worker();
                }
            });
        }
        Thread.sleep(20000);
        executor.shutdownNow();
        if (!executor.awaitTermination(5, TimeUnit.SECONDS)) {
            System.err.println("Pool did not terminate");
        }
    }
}