While reading statistics for a table in function read_statistics_for_table_is_needed we don't protect the table_share fields and there is a chance that multiple threads would try to access it at the same time.
To see this
Lets add this patch to read_statistics_for_table
and the server output is
so different threads are entering the function at the same time.
So i think we need an exclusive lock to protect the members of table_share