Employers appear to be in no rush to hire back the millions who lost their jobs in the recession, despite signs of improvement in the economy. The U.S. had a record low 2.4 million job openings in July, the Labor Department said Wednesday, the fewest since the department started tracking the figure in 2000, and half the peak of 4.8 million in mid-2007. The Rochester, N.Y., metropolitan area, where Mike Lally, 41 years old, lost his job in December, had seven unemployed people for every job opening.