About 100 people gathered in Mayor Marion Barry's back yard in Southeast Washington yesterday for a Democratic State Committee-sponsored crabfest, an annual event that celebrated the mayor as titular head of the party, but failed to produce a hoped-for show of party unity.

In addition to saluting the mayor, sponsors called for a Democratic show of strength for the general election Nov. 2, but there were no representatives yesterday from the camps of Patricia Roberts Harris, John Ray or Charlene Drew Jarvis, Barry's opponents in the Sept. 14 mayoral primary.

Democratic officials, asked about this, said that the real show of unity was at a local party rally in Georgetown earlier this month, which was attended by some representatives of the losing candidates.

Billed as "An Afternoon with Mayor Marion S. Barry Jr.," yesterday's event featured spicy crabs and beer served beneath a striped tent.

"I've invited you all to my home to say I will do all I can to build the party and make it strong," Barry told the crowd, after receiving a plaque of appreciation. "Regardless of where you were before September, I want you here with me now."

In his brief speech, Barry recalled seeing a cartoon that read, "Reaganomics will keep you in line," above which was a drawing of people in an unemployment line.

"This city has the highest unemployment that it has had since 1946," Barry said. "That means jobs will have to be a priority for the next four years of my administration."

While Barry brushed off the absence of Harris, his chief rival in the September primary, and her supporters as "sour grapes," Mary Candon, executive director of the state committee, said the purpose of the crab feast was simply to inspire an appreciation of being a Democrat.

"We are not candidate-oriented, we are party-oriented," Candon said. "We have a very difficult job because it's hard to know what it means to be a Democrat in a city like this, where the opposition is so small. We hope gatherings such as these will help us build a party identity."

Vincent H. Cohen, a Washington lawyer and member of the state committee, said he felt most of the political wounds would be healed by the Nov. 2 election.