troll farm
n. An organization whose employees or members attempt to create conflict and disruption in an online community by posting deliberately inflammatory or provocative comments.
Examples
2015
The agency had become known for employing hundreds of Russians to post pro-Kremlin propaganda online under fake identities, including on Twitter, in order to create the illusion of a massive army of supporters; it has often been called a "troll farm."
—Adrian Chen, “The Agency,” The New York Times, June 07, 2015
2014
Some of the leaked documents also detail what appear to be extensive efforts led by hundreds of freelance bloggers to comment on Russian-language sites. The bloggers hail from cities throughout Russia; their managers give them ratings based on the efficiency and "authenticity," as well as the number of domains they post from. Novaya Gazeta, Russia's only independent investigative newspaper, infiltrated its "troll farm" of commenters on Russian blogs last September
—Max Seddon, “Documents Show How Russia’s Troll Army Hit America,” BuzzFeed News, June 02, 2014
2009
This is an outrage. If the President of the National party said something similar the paid lap-bloggers of the Standard and other lefty troll farms would be rightly calling this corruption of the highest order.
—Cameron Slater, “Labour corruption laid bare,” Whale Oil, September 24, 2009
1998 (earliest)
I'd like to say that I am really not sure about this. An anonymous tip from someone who seemed quite sincere and whose address was not from the usual troll farms.
—JT Toad, “Re: Rumors a buzzin' about The Haunted Mansion in WDW” (reply), alt.disney,disneyworld, August 26, 1998