Instead of the while clause you used, you can call Thread#join to make the main thread wait for other threads.
threads = []
urls.each_value do |thing|
threads << Thread.new do
result = Net::HTTP.get(URI.parse(thing))
json_stuff = JSON::parse(result)
info = json["person"]["bio"]["info"]
thing["name"] = info
end
end
# Wait until threads are done.
threads.each { |aThread| aThread.join }