Some people might have noticed the download numbers for some of the more popular products on Eclipse Marketplace have taken a huge jump. For instance, Maven Integration for Eclipse has jumped to over 30,000 successful installs per month from the typical 6000-7000 installs per month.
We first discovered the large jump when we migrated Marketplace to Drupal 7. All of a sudden a lot of the more popular plugins were becoming a LOT more popular. It turns out for the last year we had been under-counting the installs, especially for the more popular plugins.
We use Varnish cache in front of Marketplace to cache a lot of the content. Unfortunately, Varnish was caching the url we used to count a successful install. The cache was cleared every 5 minutes, so the successful install counter was incremented only once every 5 minutes. For popular plugins, like Maven integration, this had a significant impact.
The good news is we have fixed the problem and the stats now provide a more accurate picture of reality. It also means we are seeing each month close to 300,000 successful installs of Eclipse plugins!