On Thu, Nov 7, 2019, at 15:46, Anatoli via Cyrus-devel wrote: > Bron, > > Thanks for your detailed reply and the work the FM team is doing! > > > This is not easy unfortunately with all the different datastructures, > > because it means that everything else which takes a lock is going to > > need to first take a global shared lock before it does anything else, > > and that's going to have a performance and complexity impact on > > everything - because you have to find them ALL or you might wind up > > with lock inversions down the line. > > One solution I see is to have a separate single lock, not even a lock > per se, but a barrier. I.e. before every write operation
How does that maintain consistency? I guess you don't get skew between files, but you still have to do crash recovery on every file. There's no single place to put this either. I think I still prefer the idea of a shared locks that wraps every single other lock, such that taking the snapshot pauses every attempt to start a new lock until it's done, so you always get a completely clean read equivalent to a clean shutdown. Bron. -- Bron Gondwana, CEO, Fastmail Pty Ltd br...@fastmailteam.com
