>>>>> "Y" == Yukihiro Matsumoto <matz / netlab.co.jp> writes: Y> I see. File#flock can be used to exclude control flow within same Y> process (i.e. threads), but since threads share memory space, threads Y> may share locked file descriptor. On the other hand, there's no way Y> to share locked file descriptor between processes, thus OK, I've understood. Thanks, Guy Decoux