Whether it is the cold drizzle, factory economics or the annual exodus of migrant laborers ahead of Lunar New Year, Lin Xinge is selling fewer dumplings.

Ms. Lin is chief dumpling wrapper, waitress, cashier and dishwasher for Fujian One Thousand Li Fragrant, a tiny restaurant she owns with her husband in an industrial zone of Shanghai. Just over a fence, her neighbors include iPhone maker Foxconn Technology Group and other giant industrial groups that employ legions of workers she counts as customers.

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