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On Mon, Nov 22, 2010 at 4:00 PM, Brian Bockelman <[log in to unmask]> wrote: > What is the fork safety of XrdClient? We've recently found issues where if we fork() a child process in CMSSW after open/closing a file, that some protocols which persist connections become confused when there are now two processes using the same TCP connection. > > We would prefer XrdClient to handle the issue transparently if possible. If this is not possible (and we'd strongly prefer the former), we'd like a mechanism to release all connection resource that we just call once prior to forking. We would *not* have to clean this up at a per-file basis as we have no knowledge which files are connected to which server. > > At any rate, before we get too far ahead of ourselves... what's available? Hi Brian, I don't think there is any safety mechanism for that at the moment. There is the pthread_atfork function that let's you register a couple of callbacks to be called before and after forking, so we could, in principle handle forking transparently. This function, however, is not really a standard one, so it may behave differently on different (Linux) platforms or may not be present at all. I'll have a closer look and let you know. In any case, providing a release mechanism doesn't look like a big development. Cheers, Lukasz