Hi, everyone As one of my first tasks in GSoC, I'm looking to protect the global states at sha1-file.c for future parallelizations. Currently, I'm analyzing how to deal with the cached_objects array, which is a small set of in-memory objects that read_object_file() is able to return although they don't really exist on disk. The only current user of this set is git-blame, which adds a fake commit containing non-committed changes. As it is now, if we start parallelizing blame, cached_objects won't be a problem since it is written to only once, at the beginning, and read from a couple times latter, with no possible race conditions. But should we make these operations thread safe for future uses that could involve potential parallel writes and reads too? If so, we have two options: - Make the array thread local, which would oblige us to replicate data, or - Protect it with locks, which could impact the sequential performance. We could have a macro here, to skip looking on single-threaded use cases. But we don't know, a priori, the number of threads that would want to use the pack access code. Any thought on this? Thanks, Matheus Tavares
