One of the longest running and most beloved Irish traditional music sessions in Boston is coming to an end.

Every Monday night for 29 years, musicians have gathered at the Green Briar Pub in Brighton Center. But on Monday, May 6, the musicians will assemble for one final blast of tunes.

With ancient roots spanning centuries of emigration, Irish traditional music is more vital and vibrant today than ever before. It is now played all over the world, and it’s particularly strong in the United States. The music is commonly shared and celebrated at what are called “sessions,” informal gatherings in clubs, pubs and kitchens.

Shannon Heaton, a flute player from Medford and host of the podcast "Irish Music Stories," was a regular attendee of the Green Briar session in its early days. She says one feature that defines that type of gathering is frequency.

“A session usually means a regularly occurring social event centered around Irish music — maybe, if you’re lucky, a bit of dance and some singing,” Heaton said.

Sessions are always hosted, and the personality of those hosts is key to the event's success and longevity. At the Green Briar, Terry O’Shea and Tom Sheridan kept the music flowing and made sure that everyone felt included. O’Shea, a transplanted Dubliner who plays banjo and guitar, emphasized the importance of inclusivity.

“To me, an Irish session is essentially music for everybody,” he said.

Sheridan, who grew up in Brighton but now lives in Watertown, points to the spontaneity of the repertoire: the fact that no one is playing from a set list, and that there are often opportunities for individual musicians, some not used to the spotlight, to shine.

The best sessions invite musicians of many skill levels to play tunes with each other, essentially without rehearsal. But something about this Green Briar session made it different. It was open and welcoming, and made for an old-fashioned, positive, community experience. Long-lasting friendships were forged over reels and jigs, and the sandwiches that were passed out — free — later in the evening. But the gatherings were always about the music.

Maureen Foley, a filmmaker and a fiddler from Cambridge who attended the session almost every Monday night, says it was all “about the Irish community and keeping Irish music alive, and bringing along young musicians."

"Nobody,” she said, “did that in Boston the way the people at the Green Briar did.”

Shannon Heaton pointed out the age diversity at the gatherings. For her, a special feature was the chance to learn from players who might have grown up with the music in Ireland.

“The Green Briar was a different kind of experience,” she said, “a chance to connect with older players, with seasoned musicians, people who had grown up with this music in a different way.”

One of those players with deep roots in the old country tradition was the session’s founder, Galwayman Larry Reynolds, late of Waltham, who was its true inspiration. Tommy Sheridan says that Reynolds essentially “was traditional music in Boston.”

Reynolds died in 2012, but his legacy lives on. On the night this reporter visited, the penultimate session, the name of Larry Reynolds was on everyone’s lips. These 30 years, it was pointed out, were in a very real way totally due to his inspiration and personality.

At that same bittersweet gathering was Reynold’s fellow Galwayman, Tom O’Connor. O’Conner is from Kinvara but emigrated to the U.S. in 1986. He has been the bartender at the Green Briar ever since, and was the welcoming face of virtually every one of the sessions for the past three decades.

Even in the face of the bar’s demise and the loss of this iteration of the session, O’Conner still had that broad, bright smile, and radiated a hopefulness and appreciation for what he had been a part of.

“Its been a great ride,” he said above the exuberant sounds of a dozen fiddles, seven accordions, three bodhrans, two harps, a guitar, and a set of Uilleann Pipes. “It’s been a fantastic 30 years, and I hate to see it end. But you know, these things happen, unfortunately, but sure it’s been a great ride and I really enjoyed my time here."

Correction: An earlier version of this story incorrectly stated that the Green Briar will close on May 8. It will close on May 6.