On 06/03/2012 12:15 AM, Michał Górny wrote: > On Sat, 02 Jun 2012 18:04:41 -0700 > Zac Medico <zmed...@gentoo.org> wrote: > >> #!/usr/bin/env bash >> named_pipe=$(mktemp -d)/fifo >> >> ( >> # hold the pipe open in read mode, so >> # the writer doesn't block >> sleep 3 >> ) < "$named_pipe" & > > I don't understand this part. This keeps the pipe open for reading > which obviously causes it to lose data. If you open it, you need to > read all that is there and then close.
The point is, there's always a small window of time between when a reader reads its last byte, and when it finally closes the file descriptor. During this window, there's a race where a writer can come along and write something without blocking, and have that write be destroyed when the previous reader closes the fd. > And writers are supposed to be blocked. They are forked and just write > when done, so there's no problem with keeping them alive for a short > while. Yeah, but you need locking if you want to prevent the race that I've described above. -- Thanks, Zac
