Zhang Mingming shovels burning coke into an oven at a coke plant in Pingdingshan city, Central China's Henan province, April 6, 2015. [Photo/CFP]

Zhang Mingming, a coke oven cleaner at a coke plant, is also a vendor who owns a booth that sells grilled glutenous snack in Pingdingshan city, Central China's Henan province.

The coke plant has been open for 26 years and its workers are 40 years old on average. Since the coke sales market is sluggish, almost half of the employees are seeking part-time jobs outside the plant.

Zhang works from 5 pm to 12 am in the coke plant every day, and starts selling grilled glutenous snacks on the street at 3 pm. Each month, he earns 2,300 yuan in the plant and makes more than 2,000 yuan by selling the snacks.

Although working two jobs is hard, Zhang is satisfied with the current situation as he can make more money.