HHVM is a much, much smaller undertaking than rebuilding Facebook from scratch. Wired did another article from the same source interviews about just how big Facebook is these days: http://www.wired.com/wiredenterprise/2013/04/facebook-window...
Building HHVM was a fraction of the effort, and did not require that we sit on our hands while the competition beat us up during a rewrite.
HHVM is a much, much smaller undertaking than rebuilding Facebook from scratch. Wired did another article from the same source interviews about just how big Facebook is these days: http://www.wired.com/wiredenterprise/2013/04/facebook-window...
Building HHVM was a fraction of the effort, and did not require that we sit on our hands while the competition beat us up during a rewrite.