Aihnss.511 net.news utzoo!decvax!ucbvax!mhtsa!ihnss!warren Fri Dec 4 15:16:19 1981 Centralized versus distributed indices One aspect of centralized .uindex files that Duke may not have forseen appeared when we installed "A" netnews on some of the general use unix machines in BTL. These machines typically have lots of registered users (~500 entries in /etc/passwd), but few have contact with netnews. There is also a lot of churn, as people are moved from one machine to another to balance the load. In this environment, rnews started to run for very long periods of time. Most of that time seemed to be spent in making .uindex correspond with /etc/passwd, and then going back and recoputing the bitmap. Since this is a (# of users) X (# of articles) sort of problem, it takes forever with 500 users and any significant number of articles! The "B" version doesn't suffer from this, because of its distributed index scheme. This strikes me as vastly preferable, because it distributes the time spent doing the newscheck rather than focussing it on the Daemon news receiving process, and it is much more robust. (The A version was always loosing index files due to locking problems, primarily because of the length of time it took rnews to run). A simple fix to our problem with the A version was to remove the code that put users in /etc/passwd that were not in .uindex into .uindex. This cut the run-time considerably, as the number of users was now 5-10 as compared with 500!. The only adverse effect is that you must actively subscribe in order to have the system keep track of news for you. I don't think that this is a real problem, as most people want much more than the default subscription list. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.