NEW YORK, Nov 23 (Reuters) - Retailers ranging from Walmart (WMT.N) to Barnes & Noble are installing cameras or locking away items to deter shoplifters and thieves as they brace for a post-pandemic rush of holiday shoppers this year.The retail industry has decried theft this holiday season as it struggles with excess inventories and a pullback in consumer spending at a time of high inflation.SURVEILLANCE AND STROBE LIGHTSA sign of the times can be seen in the small communities of Paducah, Kentucky, and Opelika, Alabama, where Walmart, J.C. Penney, Walgreens (WBA.O) and other major retailers have brought in large, mobile surveillance units that record all activity in their parking lots.One of the retailer's stores in Virginia on Tuesday was the scene of the latest mass shooting in the United States, when a manager opened fire and killed six people before turning the gun on himself.P&G last week said it is investing in in-store displays to avoid having its razor blades stuck in glass casing, while shoppers complain the locked displays and cables slow them down and force them to find staff who can set the merchandise free."