Invalid RSS URL in RSS Widget Causes Server Slow Down

[tgiokdi]

I have a WP Network with 50+ sites, two of them have rss feeds in their footers that link back to each other, using the default WP widgets. Months ago I accidentally put just the base URL in one of those widgets, which caused apache2 workers to endlessly try to connect to the invalid RSS URL, using all available workers and increasing the server load 10x. I found the error by doing some informative apache status queries, then some traces on the PIDs that were endlessly looping themselves. I was able to zero in on the culprit because these two sites have little to no traffic, but were taking 90% of the server usage.

I've been able to replicate this, it usually takes a couple hours for the apache2 workers to reach a point that they start to effect other sites on the network. It'd be nice if that url is deemed "invalid" for purposes of the RSS feed display that it not be attempted again. My concern is that further down the site one of the site admins will make the same error I did and cause the entire network to slow down again.

This is with a default LAMP installation.