For most programs, yes they have done their job. However, in certaint categories of applications (for example, server software) it's somewhat of a leaky abstrac

For most programs, yes they have done their job. However, in certaint categories of applications (for example, server software) it's somewhat of a leaky abstraction. Garbage collector sweeps, circular references, etc are all pains which force you to be aware of how the vm is managing your memory. For an impression, see this excellent blog series on how a certain garbage collector sweep issue was solved: http://blog.cloudera.com/blog/2011/02/avoiding-full-gcs-in-hbase-with-memstore-local-allocation-buffers-part-1/ http://blog.cloudera.com/blog/2011/02/avoiding-full-gcs-in-h...