Hi, folks On Thu, Dec 19, 2019 at 5:27 PM Matheus Tavares Bernardino <matheus.bernardino@xxxxxx> wrote: > [...] > However, re-inspecting the code, it seemed to me that we might already > have a thread-safe mechanism. The window disposal operations (at > close_pack_windows() and unuse_one_window()) are only performed if > window.inuse_cnt == 0. So as a thread which reads from the window will > also previously increment its inuse_cnt, wouldn't the reading > operation be already protected? > > Another concern would be close_pack_fd(), which can close packs even > with in-use windows. However, as the mmap docs[1] says: "closing the > file descriptor does not unmap the region". > > Finally, we also considered reprepare_packed_git() as a possible > conflicting operation. But the function called by it to handle > packfile opening, prepare_pack(), won't reopen already available > packs. Therefore, IIUC, it will leave the opened windows intact. > > So, aren't perhaps the window readings performed outside the > obj_read_mutex critical section already thread-safe? Any thoughts on this? > Thanks, > Matheus > > [1]: https://linux.die.net/man/2/mmap
