This is expected result. mysql_free_result() just decreases the refcount to the result and actual freeing happens during request shutdown (if refcount to the result is 0!).

Well maybe, but I checked MySql API mysql_free_result() source code and there's no reference counting logic, it just frees stuff. I suppose this is PHP's mysql_free_result() implementation that checks reference count, and it was intended as a kind of service to prevent people from losing a result set while there is still another reference around. But I do not think this is really expected and people use it this way by calling mysql_free_result() first and then using the same result again from another variable. I think most people expect PHP mysql_free_result() to call MySql mysql_free_result directly whatsoever. 

Also, I suppose PHP might call mysql_free_result() automatically when reference count goes to 0 even before the script is over, for example if I execute an Sql-query inside a function and then return from it without saving the result PHP might call mysql_free_result() when destroying the variable. 

But it is not obvious that reference count check should be done at direct calls to mysql_free_result() as then I say I want it, no matter how many references I still have. Also, it is not clear which exactly variable is dereferenced from the result set as the variable passed to mysql_free_result() still exists after the call and I can use it again. If I call mysql_free_result() with the same variable again it does free the result :)

A clarification: by saying "PHP might call mysql_free_result() automatically" I do not mean a feature request, I mean I suppose PHP already does so.