General

NetNewsWire is a really great news aggregator for Mac OS X. But it got one really huge issue: when you have more than 30 or 40 RSS/RDF feeds in your NetNewsWire, the downloads are being parallelized rather serialized. Conceptually, this is a good feature, since it makes the downloads faster - at least on a huge pipe. But the parallelization leads to a number of side effects in combination with other, pretty common, software with not really much bandwidth available:



I am (still) getting my internet connection at home via ISDN, that means 64 kbps. I am also using a Squid HTTP proxy and tinydns + dnscache from the djbdns suite. When NetNewsWire starts downloading all the RSS/RDF feeds, a lot of parallel connections are opened to the proxy, which in turn, does a lot of parallel DNS requests. Since most of the host names that are being queried aren't in the DNS cache, the DNS server starts a lot of parallel DNS requests, leading to a totally saturated internet connection. And since DNS is UDP based here, packets are dropped, and the DNS server has to do packet retransmissions, leading to even more traffic, and more bandwidth saturation. The only solution to stop this is to either wait for a very long time or to close the dialup connection, restart tinydns + dnscache, and reconnect the dialup connection.



And that manual intervention makes NetNewsWire on ISDN practically unusuable. I have to admit, I never tried it out without caching DNS server and HTTP proxy, but I doubt it will be that different. And no, getting a faster internet connection is (currently) not an option, unless somebody's willing to pay it for me.