On Apr 6, 2:23 pm, "Diez B. Roggisch" <de...@nospam.web.de> wrote: > > This is a classical synchronization problem with a classical solution: > > You treat the readers as a group, and the writers individually. So you > > have a write lock that each writer has to acquire and release, but it is > > acquired only by the first reader and released by the last one. > > Therefore you need a counter of the number of readers, and manipulations > > of this counter must be protected by another lock. > > I was going to suggest a similar approach but refused to because of a > problem I see with your code as well - if the readers are reading very > fast (the OP didn't state what his actual application is, so it might > not be a consumer-producer scheme which I don't think a dict would be > the natural choice anyway) they can block the writer from writing > alltogether.
You could implement some kind of fair ordering where whoever requests a lock first is guaranteed to get it first, but I can't think of a way to do that without requiring all readers to acquire two locks. Carl Banks -- http://mail.python.org/mailman/listinfo/python-list
