Comment by technoweenie

FWIW I've always heard it described as a thundering herd. Though, your description is spot on, according to Wikipedia [1]. The problem the article discusses is called a cache stampede or dog pile [2].

[1] https://en.wikipedia.org/wiki/Thundering_herd_problem

[2] https://en.wikipedia.org/wiki/Cache_stampede

I wouldn't fault anyone for getting these similar names mixed up though.