Redis 4.x Cookbook

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There are blocking versions for the command LPOP and RPOP: BLPOP and BRPOP. They both pop an element from the left or right end of the list, such as the corresponding non-blocking commands, but the client will be blocked if the list is empty. A timeout in seconds has to be specified in these blocking pop commands for the maximum time to wait. Zero timeout means waiting forever. This feature is useful in the job dispatcher scenario, where multiple workers (Redis Clients) are waiting for the dispatcher to assign new jobs. The workers just use BLPOP or BRPOP on a job list in Redis. Whenever there is a new job, the dispatcher pushes the job into the list, and one of the workers will pick it up.

Let's open two more Terminals, which ...