Is there anything out there freeware or commercial that can facilitate analysis of memory usage by a PHP application? I know xdebug can produce trace files that shows memory usage by function call but without a graphical tool the data is hard to interpret. 

Ideally I would like to be able to view not only total memory usage but also what objects are on the heap and who references them similar to [Jprofiler](http://www.codework.com/jprofiler/product.htm).