To answer your second question, you might want to look at concurrent garbage collection. Here's the obligatory wiki link: http://en.wikipedia.org/wiki/Garbage_

To answer your second question, you might want to look at concurrent garbage collection. Here's the obligatory wiki link: http://en.wikipedia.org/wiki/Garbage_collection_ http://en.wikipedia.org/wiki/Garbage_collection_(computer_science)#Stop-the-world_vs._incremental_vs._concurrent