Amazon’s new chief executive, Andy Jassy, who joined the company in 1997 and has overseen its fast-growing cloud computing business, says the key to long-term success is reinvention. “You want to be reinventing when you are healthy, you want to be reinventing all the time,” Jassy, 53, said in December at a company forum. “You have got to be manancial and relentless and tenacious about getting to the truth… You have to know what’s working and what’s not working.” He cited Netflix’s decision to cannibalize its own DVD rental business in favor of streaming. The focus on the future is fitting given Jassy’s career is defined by his leading Amazon into a wholly new market: cloud computing. Amazon Web Services rents space and software programming for customers to run their technical operations on the company’s servers. The arm now fuels Amazon’s profits and dominates the cloud market just as the …