Hacker News Reader

Comment by ryanmccullagh | Hacker News Reader

what's the difference between this and valgrind?

A major difference is that purify is a binary transformation performed before or after linking. Valgrind/memcheck is a virtual machine that jit-compiles executable code and adds its instrumentation in the process. So, with purify, your linked executable includes the checks. With valgrind, the unmodified executable can run with or without checks.

And for a more practical comparison: https://valgrind.org/gallery/survey_03/q4.html

The takeout is: valgrind is free and doesn't require recompilation, purify has a more complete UI, they both have similar performance impact and bug-finding abilities.

Also, Purify runs on Windows.

I used Purify back in the day, and while it worked well, getting it working was a royal PITA. IIRC it was necessary to recompile EVERYTHING with Purify.

Anyway, I would think the gold standard these days is clang's Address Sanitizer (https://github.com/google/sanitizers/wiki/AddressSanitizer). clang/ASAN also runs on Mac in addition to Linux.

Having never used Purify back in the day, I really wonder, do you think address sanitizer is an adequate or better replacement for Purify?

It's been a while, but IIRC ASAN catches most/all of the memory-related errors that Purify did.

Purify did have a debugger-like GUI that would break on errors, which could be handy.

valgrind can also do most of the same checks, but is much slower.

On my team we use both

Reply on news.ycombinator.com