High concurrency red envelope grabbing: How to use Redis to accurately control the red envelope amount allocation and avoid over-issuance?

Efficiently solve the problem of high concurrent red envelope grabbing amount allocation

In high-concurrency red envelope grab activities, it is crucial to accurately control the allocation of red envelope amounts. This article takes a specific scenario as an example: the total amount is 10 yuan, and the random payment is 0.1 yuan to 0.5 yuan (after the paid amount exceeds 5 yuan, it will be reduced to 0.01 yuan to 0.02 yuan). How to avoid over-issuance of amounts under high concurrency?

Some solutions, such as using message queues, do not apply because they need to return the amount in real time. Using Redis's brpop blocking command cannot directly solve the amount error problem caused by concurrent calculations.

Best solution: Pre-calculate and store the red envelope amount

The most effective solution is to pre-calculate all red envelope amounts before the event starts and store them in Redis (for example, using a list). According to the rules (0.1-0.5 yuan, 0.01-0.02 yuan after exceeding 5 yuan), each red envelope amount is randomly generated to ensure that the total amount is 10 yuan.

When a user grabs a red envelope, he or she directly uses Redis's RPOP command to pop up the element from the list, which is the user's red envelope amount. This method avoids concurrent calculations, ensures the accuracy and fairness of the amount, and meets the need to return results in real time.

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