How can I verify lock-free algorithms?

Question

In theory, it should be possible to at least brute force a verification of a lock-free algorithm (there are only so many combinations of function calls intersecting). Are there

Answer 1

If you want to really verify lock-free code (as opposed to exhaustively testing a small instance), you can use VCC (http://vcc.codeplex.com), a deductive verifier for concurrent C code which has been used to verify some interesting lock-free algorithms (e.g. lock-free lists and resizable hashtables using hazard pointers, optimistic multiversion transaction processing, MMU virtualization, various synchronization primitives, etc.). It does modular verification, and has been used to verify nontrivial chunks of industrial code (up to about 20KLOC).

Note, however, that VCC is a verifier, not a bug hunting tool; you will have to do substantial annotation on your code to get it to verify, and the learning curve can be a bit steep. Note also that it assumes sequential consistency (as do most tools).

BTW, peer review is not a good way to verify a concurrent algorithm (or even a sequential one). There's a long history of famous people publishing concurrent algorithms in important journals, only to have bugs discovered years later.