Puma is Now the Recommended Ruby Webserver | Heroku Dev CenterPuma is Now the Recommended Ruby WebserverChange effective on 23 January 2015 Heroku now recommends using the Puma webserver. The previously recommended webserver, Unicorn, is susceptible to slow client attacks. If you are using Unicorn on Heroku please migrate to Puma. For more information read Deploying Rails Applications with the Puma Web Server.
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