문전성시가 · 문전성시를
a crowd of visitors, being swamped with customers
Example
그 식당은 방송에 나온 뒤로 문전성시를 이루고 있어요.
Since it was on TV, that restaurant has been packed with customers.
Word parts
문 gate+전 front+성 become+시 market
Literally 'a market forms in front of the gate' — so many visitors.
Good to know
Common collocation: 문전성시를 이루다 'to be swamped with visitors'.