SAN FRANCISCO — One of the nation’s most celebrated gay bars may soon go out of business after a new landlord more than doubled the rent.

At 50 years old, the Stud is the longest-running gay bar in San Francisco. It’s known throughout the country as one of the bohemian, gender-bending, anything-goes institutions that made the city into a gay mecca. In June the building was sold, and the bar’s owner received a notice that the monthly rent would leap from $3,800 to $9,500 in September. On Sunday, he called an emergency meeting to break the news to regulars. Old-timers lament that many of San Francisco’s dilapidated and diverse areas are disappearing.