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InterNetNews...[Salz92]: Conclusions and Comparisons

The InterNetNews architecture works. Profiling a production installation for 24 hours showed that open (2) accounted for 10% of the run time. Since the server only does one open (2) per article, it is not clear if any other performance tuning is needed. The profiling overhead accounted for 5% of the run-time.

Several optimizations are available because there is only one process, and because it is always running. For example, avoiding duplicates is an integral part of the server. If a second site offers an article while a first site is sending it, the NNTP code will put the channel to ``sleep'' for a short while before replying to the second offer. This is usually enough time to have the first site finish sending the article, reducing the number of duplicates from hundreds to nearly none, with no external programs.

Since the server is always running, the system has a much smoother performance curve. As a result, it ``feels'' much faster to users.

Another unexpected benefit is that articles are accepted or rejected synchronously. A user can post an article, and by the time their posting agent has returned, it has been written to the spool directory and queued for remote transfer. If there is a problem such as having an illegal newsgroup specified, the user founds out immediately.

The design of the server seems to be very good, split into abstractions that are very independant. For example, sites have no knowledge of incomming NNTP connections. Using callbacks lets each portion of the server safely do I/O without worrying that it might affect other parts. Much of the Usenet processing becomes trivial when serialized, such as access to the history file.

The design has also led to a fairly small program: it is under 13,000 lines, and about 20% of them are comments. This compares favorable to the 7,400 lines in the equivalent C News program and the 7,600 lines in the NNTP reference implementation.

InterNetNews(Salz) [Source:"InterNetNews: Usenet transport for Internet sites"] [Copyright: 1992 Rich Salz]
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