The man who developed these two concepts was Mikhail Gorbachev. Gorbachev was the last leader of the Soviet Union. He took power in 1985 and remained in power until the Soviet Union fell apart in 1989.
By the time that Gorbachev took power, the Soviet Union was in terrible shape and was declining even further. Most observers feel that the Soviet economy was extremely weak because of the fact that it was a command economy. There were no real market forces to encourage Soviet farms and industries to improve themselves and so they were terribly inefficient. The Soviet economy was further harmed by the need that its leaders felt to keep up with the United States in a very expensive competition for military might. In addition to all of this, people in the Soviet Union were unhappy because they wanted more rights. They wanted to live in a less repressive system.
When Gorbachev came to power, he hoped to reform this system. He did not want to overturn the system at all. Instead, he felt that he could simply make some reforms that would improve the system greatly while still allowing it to survive more or less intact. In an attempt to achieve these goals, Gorbachev developed and tried to implement the policies of glasnost (political openness) and perestroika (economic restructuring).