I notice with PHP if a connection cannot be established to a mysql
server with mysql_connect() PHP will timeout and never try the backup
server. In this example:

$db = mysql_connect('db1.local.net', 'username', 'password');
if (!$db) {
$db = mysql_connect('db2.local.net', 'username', 'password');
}

This works great and connects to the 2nd database if the 1st one
rejects the connection completely; however, if the 1st db is under high
load and doesn't respond for 10+ seconds it never jumps to the 2nd one.
Curious if there's a better way to accomplish this. If the 1st db
doesn't respond in 1 second max I'd like to hop to the 2nd one.

Does the newer mysqli_connect handle this better, anyone know?

Don't know about mysqli_connect() but you could use fsockopen() and set
a short timeout, close the connection and then reconnect with
mysql_connect();

I would hope there was a tidier solution that this though. Perhaps load
balancing on the backup server, in relation to how much it can handle?

Another issue I'm trying to overcome is locking issues. We do
dual-master replication, and in the event a table is locked on db1, it
should still be readable on db2. It would be great to have a way to
timeout a connection if no response rcv'd in say.. 2 seconds for it to
kick to the 2nd server.