A while back, someone started a thread based on the claim that Java wasn't used for large scale production applications. It smelled like a troll thread, but The fundamental topic has some validity. The answer is, yes, Java is used for huge sites.
Peak traffic of 874,560 Tweets per minute without Fail Whale coming up for air
By Neil McAllister in San Francisco • Get more from this author
Micro-blogging site Twitter experienced record traffic as the results of the 2012 US Presidential election were announced on Tuesday night, but the service never faltered despite the increased load – something Twitter engineers credit to the company's move from Ruby to Java for its backend software.
According to a blog post by Mazen Rawashdeh, Twitter's VP of infrastructure operations engineering, Twitter users posted an average of 9,965 messages per second between the hours of 8:11pm and 9:11pm Pacific Time.
During a single second at 8:20pm, Twitter users produced 15,107 new posts, Rawashdeh writes, and during the peak traffic period of the evening they generated 874,560 posts in a single minute.
Actually, it would be more accurate to say that Twitter is a giant commercial user of the JVM, but they seem to be using Scala rather than Java in a lot of areas.