School of Computing

A study of Java demographics

Richard Jones and Chris Ryder

In Steve Blackburn, editor, Proceedings of the 2008 International Symposium on Memory Management (ISMM'08), pages 182-196, Tucson, AZ, June 2008. ACM Press.


Researchers have long strived to exploit program behaviour in order to improve garbage collection efficiency. For example, by using a simple heuristic, generational GC manages short-lived objects well, although longer-lived objects will still be promoted to an older generation and may be processed repeatedly thereafter. In this paper, we provide a detailed study of Java object lifetimes which reveals a richer landscape than the generational view offers.

Allocation site has been claimed to be a good predictor for object lifetime, but we show that object lifetime can be categorised more precisely than 'short-lived/long-lived/immortal'. We show that (i) sites allocate objects with lifetimes in only a small number of narrow ranges, and (ii) sites cluster strongly with respect to the lifetime distributions of the objects they allocate. Furthermore, (iii) these clusterings are robust against the size of the input given to the program and (iv) are likely to allocate objects that are live only in particular phases of the program's execution. Finally, we show that, in contrast to previous studies, (v) allocation site alone is not always sufficient as a predictor of object lifetime distribution but one further level of stack context suffices.

Download publication 537 kbytes (PDF)

Bibtex Record

author = {Richard Jones and Chris Ryder},
title = {A Study of {J}ava Demographics},
month = {June},
year = {2008},
pages = {182-196},
keywords = {determinacy analysis, Craig interpolants},
note = {},
doi = {},
url = {},
    publication_type = {inproceedings},
    submission_id = {7669_1210253319},
    ISBN = {978-1-60558-134-7},
    booktitle = {Proceedings of the 2008 International Symposium on Memory Management (ISMM'08)},
    editor = {Steve Blackburn},
    address = {Tucson, AZ},
    publisher = {ACM Press},
    refereed = {yes},

School of Computing, University of Kent, Canterbury, Kent, CT2 7NF

Enquiries: +44 (0)1227 824180 or contact us.

Last Updated: 21/03/2014