We received feedback from a number of users in the MySQL community that the command SHOW ENGINE INNODB MUTEX remains useful in a number of scenarios. We listened, and the command is scheduled to make a return in MySQL 5.7.8.
To lessen overhead, the command will now feature a mechanism to enable and disable metrics collection. This is documented in the manual here:
SET GLOBAL innodb_monitor_enable='latch'; SET GLOBAL innodb_monitor_disable='latch';
Thank you for helping make a better MySQL!