I use singleton to increase response for database connection.
But when there is many users that which send request in same time, instances of one connection make a bottle neck, So I use another approach in getInstace() method :
public class jjDatabaseWeb {
private static final DatabaseType dbType = DatabaseType.MySql;
private static String password;
private ResultSet resultSet;
private static String serverHost = "127.0.0.1"; //localhost";
private static String port = "3306";
private static String databaseName = "db_university";
static String url2;
private Connection connection;
private static jjDatabaseWeb accessor;
private static jjDatabaseWeb accessor2;
private static jjDatabaseWeb accessor3;
private static jjDatabaseWeb accessor4;
private static jjDatabaseWeb accessor5;
private static jjDatabaseWeb accessor6;
private static jjDatabaseWeb accessor7;
private static jjDatabaseWeb accessor8;
private static jjDatabaseWeb accessor9;
private static jjDatabaseWeb accessor10;
private static int counter = 0;
private static int counter2 = 0;
private jjDatabaseWeb() throws ClassNotFoundException, SQLException {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/db_university?characterSetResults=UTF-8&characterEncoding=UTF-8&useUnicode=yes", "root", "m123456");
//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
System.out.println("database driver name is ok");
}
public static synchronized jjDatabaseWeb getInstance() throws SQLException, ClassNotFoundException {
counter++;
System.out.println("+++++=====>>>> number of connection user" + counter);
if (accessor == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 1 ");
System.out.println("############################################");
accessor = new jjDatabaseWeb();
}
if (counter > 7) {
System.out.println("-------------------------------" + counter2);
counter2++;
if (counter2 % 10 == 1) {
if (accessor2 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 2");
System.out.println("############################################");
accessor2 = new jjDatabaseWeb();
}
return accessor2;
}
if (counter2 % 10 == 2) {
if (accessor3 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 3");
System.out.println("############################################");
accessor3 = new jjDatabaseWeb();
}
return accessor3;
}
if (counter2 % 10 == 3) {
if (accessor4 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 4");
System.out.println("############################################");
accessor4 = new jjDatabaseWeb();
}
return accessor4;
}
if (counter2 % 10 == 4) {
if (accessor5 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 5");
System.out.println("############################################");
accessor5 = new jjDatabaseWeb();
}
return accessor5;
}
if (counter2 % 10 == 5) {
if (accessor6 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 6");
System.out.println("############################################");
accessor6 = new jjDatabaseWeb();
}
return accessor6;
}
if (counter2 % 10 == 6) {
if (accessor7 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 7");
System.out.println("############################################");
accessor7 = new jjDatabaseWeb();
}
return accessor7;
}
if (counter2 % 10 == 7) {
if (accessor8 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 8");
System.out.println("############################################");
accessor8 = new jjDatabaseWeb();
}
return accessor8;
}
if (counter2 % 10 == 8) {
if (accessor9 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 9");
System.out.println("############################################");
accessor9 = new jjDatabaseWeb();
}
return accessor9;
}
if (counter2 % 10 == 9) {
if (accessor10 == null) {
System.out.println("############################################");
System.out.println("NEW DB CONNECTION 10");
System.out.println("############################################");
accessor10 = new jjDatabaseWeb();
}
return accessor10;
}
}
counter2 = 0;
return accessor;
}
}
I never closed connection And use singleton, it has some benefit.
If there was created connection,new connection dose not makes, so fetching data is faster(making connection is time consuming )
In non busy time we have one connection is single tone mode and if there is max 7 request concurrent the program get instance of one connection.
In busy time when there is many requests waited for one connection, it make 9 other connection and share new requests between them.
I test it in wrong condition, and send 40 request in one second from 3 different browser to one method and it takes 2 minutes, but when i use only singleton it takes about 6 minutes.
But when i repeat this test some error occurred for some requests like "Heap space error" and Java invocation target exception.
note that in output i saw counter=28 (that means there was 28,27 in peak task waited for connection)
I have not problem for first time running of batch requests , but when i repeat tis test it has some error reason of heap space lake.
