MySQL processes in Locked state - WordPress database
After upgrading WordPress to 3.1.1, I am occasionally experiencing 503 errors from Apache, and "Error establishing a database connection" messages. The database seems to be refusing connections.
I have noted that when the database is unavailable, there are a large number of MySQL processes in the "Locked" state. These processes are performing queries related to the WordPress database. What could cause so many processes to become "Locked" and how can I fix this?