com.zaxxer.hikari.pool.PoolInitializationException: Exception during pool initialization

Question

I currently have one open pool that connects to my main database and it works perfectly. But now, I want to open a new pool for another database. I set up the new pool EXACTLY how I setup the first one, obviously I edited the database name, etc. No errors appear when I load my setupHikari() method but once an actual statement is about to run I get a lot of errors.

Caused by: com.zaxxer.hikari.pool.PoolInitializationException: Exception during pool initialization at com.zaxxer.hikari.pool.HikariPool.initializeConnections(HikariPool.java:580) ~[?:?] at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:150) ~[?:?] at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:96) ~[?:?] at com.thecodexmc.GameLibrary.xenforo.XenUtils.getUserGroupID(XenUtils.java:51) ~[?:?] at com.thecodexmc.GameLibrary.game.GameListeners.onLogin(GameListeners.java:334) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_79] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_79] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_79] at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_79] at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] ... 13 more Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.7.0_79] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[?:1.7.0_79] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.7.0_79] at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[?:1.7.0_79] at com.mysql.jdbc.Util.handleNewInstance(Util.java:407) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.Util.getInstance(Util.java:382) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3593) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3525) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:931) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4031) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1296) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2338) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2371) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2163) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.7.0_79] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) ~[?:1.7.0_79] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[?:1.7.0_79] at java.lang.reflect.Constructor.newInstance(Constructor.java:526) ~[?:1.7.0_79] at com.mysql.jdbc.Util.handleNewInstance(Util.java:407) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:378) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:440) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:138) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.mysql.jdbc.jdbc2.optional.MysqlDataSource.getConnection(MysqlDataSource.java:108) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] at com.zaxxer.hikari.pool.HikariPool.addConnection(HikariPool.java:495) ~[?:?] at com.zaxxer.hikari.pool.HikariPool.initializeConnections(HikariPool.java:564) ~[?:?] at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:150) ~[?:?] at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:96) ~[?:?] at com.thecodexmc.GameLibrary.xenforo.XenUtils.getUserGroupID(XenUtils.java:51) ~[?:?] at com.thecodexmc.GameLibrary.game.GameListeners.onLogin(GameListeners.java:334) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_79] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_79] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_79] at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_79] at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[server.jar:git-PaperSpigot-7aa4900-62a2169] ... 13 more

What am I doing wrong here? Here is my XenSQL class, which is what's causing the problem.

public class XenSQL {

private static XenSQL instance;
private HikariDataSource hikari;

public XenSQL() {
    instance = this;
}

public void setupHikari() {
    hikari = new HikariDataSource();
    hikari.setMaximumPoolSize(10);
    hikari.setDataSourceClassName("com.mysql.jdbc.jdbc2.optional.MysqlDataSource");
    hikari.addDataSourceProperty("serverName", host);
    hikari.addDataSourceProperty("port", port);
    hikari.addDataSourceProperty("databaseName", database);
    hikari.addDataSourceProperty("user", user);
    hikari.addDataSourceProperty("password", password);
    System.out.println("[XenSQL] HikariCP connected to the database successfully.");
}

public void queryUpdate(String query) {
    Connection connection = null;

    try {
        connection = hikari.getConnection();
        PreparedStatement pre = connection.prepareStatement(query);
        pre.executeUpdate();
        pre.close();
    } catch (SQLException e) {
        System.out.println("[XenSQL] Error whilst executing the query \"" + query + "\": " + e.getMessage());
    } finally {
        closeConnection(connection);
    }
}

public void closeConnection(Connection connection) {
    if(connection != null) {
        try {
            connection.close();
        } catch(SQLException e) {
            e.printStackTrace();
        }
    }
}

public HikariDataSource getHikari() {
    return hikari;
}

public static XenSQL getInstance() {
    return instance;
}
}

I removed the SQL information for obvious reasons, but I don't know what's the issue here.

Answer 1

For MySQLNonTransientConnectionException: Too many connections

some options you have are:

1. Kill some connections manually
   Using SHOW PROCESSLIST to view all connections, then KILL the process ID's you want to kill.
2. Edit timeout setting to have the MySQL daemon kill the inactive processes itself
   ie. in my.cnf:
   wait_timeout = 28800
   interactive_timeout = 28800
3. Raise the connection count
   ie. in [mysqld] section of my.cnf:
   max_connections = 100
4. Limit the amount of connections per username
   ie. in [mysqld] section of my.cnf:
   max_user_connections = 50
5. Restart MySQL server

HTH