Simple, just add this line at preamble.
\usepackage[style=authoryear]{biblatex}
\renewcommand{\nameyeardelim}{\addcomma\addspace}
\usepackage[style=authoryear]{biblatex}
\renewcommand{\nameyeardelim}{\addcomma\addspace}
My sky is high, blue, bright and silent.

Nugroho's (almost like junk) blog
By: Nugroho Adi Pramono