test_shm_mq is an example of how to use dynamic shared memory
and the shared memory message queue facilities to coordinate a user backend
with the efforts of one or more background workers.  It is not intended to
do anything useful on its own; rather, it is a demonstration of how these
facilities can be used, and a unit test of those facilities.

For more detailed instructions, refer to the "README" file in the "src/test/modules/test_shm_mq" directory.
