allout-widgets-maintain-tally is a variable defined in `allout-widgets.el'.
Its value is

If non-nil, maintain a collection of widgets, `allout-widgets-tally'.

This is for debugging purposes.

The tally shows the total number of item widgets in the current
buffer, and tracking increases as new widgets are added and
decreases as obsolete widgets are garbage collected.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.