# File lib/rack/session/pool.rb, line 44
44:       def get_session(env, sid)
45:         session = @pool[sid] if sid
46:         @mutex.lock if env['rack.multithread']
47:         unless sid and session
48:           env['rack.errors'].puts("Session '#{sid.inspect}' not found, initializing...") if $VERBOSE and not sid.nil?
49:           session = {}
50:           sid = generate_sid
51:           @pool.store sid, session
52:         end
53:         session.instance_variable_set('@old', {}.merge(session))
54:         return [sid, session]
55:       ensure
56:         @mutex.unlock if env['rack.multithread']
57:       end