Today, one of our MySQL database suddenly went unresponsive. The first thing I noticed was the following lines in the error.log:
InnoDB: Unable to lock /path/to/ibdata1, error: 11 InnoDB: Check that you do not already have another mysqld process InnoDB: using the same InnoDB data or log files.
Upon further investigation, I found a not perfectly matched issue but does look similar: http://forums.mysql.com/read.php?22,22344,24497#msg-24497. I took a chance and did the following: