Bug #49537 driver.connect is connecting just to first slave, and if it is down it hangs

Description:
Hi,
I'm trying to use the replication awareness of mysql driver.
I took your general example (see "how to repeat" section).
Than I stopped the first slave in the list and ran it to see if it will connect the next slave in the list.
driver.connect hung until I started the slave again...

Also - when I ran it in a loop with readonly = true. I always got connection to the first slave and not to the others. I would expect:

1st connection - 1st slave
2st connection - 2st slave
3st connection - 3st slave
4st connection - 1st slave
...

Thanks,
Zohar

How to repeat:
package com.myApp.CJTest;

import java.sql.Connection;
import java.sql.ResultSet;
import java.util.Properties;
import com.mysql.jdbc.ReplicationDriver;

public class ReplicationDriverDemo {

	public static void main(String[] args) throws Exception 
	{
	
		ReplicationDriver driver = new ReplicationDriver();
		Properties props = new Properties();
		// We want this for failover on the slaves
		props.put("autoReconnect", "true");
		// We want to load balance between the slaves
		props.put("roundRobinLoadBalance", "true");
		props.put("user", "root");
		props.put("password", "");
	
		// Looks like a normal MySQL JDBC url, with a
		// comma-separated list of hosts, the first
		// being the 'master', the rest being any number
		// of slaves that the driver will load balance against
		Connection conn = 
			driver.connect("jdbc:mysql://m1,s1,s2,s3/test",
				props);
	
	
		// Perform read/write work on the master
		// by setting the read-only flag to "false"
		conn.setReadOnly(false);
		conn.setAutoCommit(false);
		ResultSet rs = null;
		
		rs = conn.createStatement().executeQuery("SELECT host FROM test.hostname");
		
		if (rs.next())
			System.out.println(rs.getString(1));
	
		// Now, do a query from a slave, the driver automatically picks one
		// from the list
		conn.setReadOnly(true);
	
		rs = conn.createStatement().executeQuery("SELECT host FROM test.hostname");
		if (rs.next())
			System.out.println(rs.getString(1));
	}
}

Suggested fix:
driver.connect hung until I started the slave again...
-- I would expect it to connect to the next available slave.

Also - when I ran it in a loop with readonly = true. I always got connection to the first slave and not to the others. 

I would expect:
  1st connection - 1st slave
  2st connection - 2st slave
  3st connection - 3st slave
  4st connection - 1st slave
  ...

Proposed patch

Attachment: diff.txt (text/plain), 1011 bytes.

Pending Mark's review and based on Todd's test I'm marking this verified as described with workaround being "use most trusted box for first slave".

Fixed for 5.1.11, from the changelog:

- "Replication" connections (those with URLs that start with 
      jdbc:mysql:replication) now use a jdbc:mysql:loadbalance connection
      under the hood for the slave "pool". This also means that one can set
      load balancing properties such as "loadBalanceBlacklistTimeout" and
      "loadBalanceStrategy" to choose a mechanism for balancing the load and
      failover/fault tolerance strategy for the slave pool. This work was done
      in order to fix Bug#49537.

A 'change' entry has been added to the 5.2.11 changelog:

Replication connections, those with URLs that start with jdbc:mysql:replication, now use a jdbc:mysql:loadbalance connection for the slave pool. This means that it is possible to set load balancing properties such as loadBalanceBlacklistTimeout and loadBalanceStrategy in order to choose a mechanism for balancing the load, and failover or fault tolerance strategy for the slave pool.