A threatened strike by dock workers that would have closed much of the port of Boston and other east coast ports has been put off for at least 30 days, after shippers and longshoremen came to terms on a major sticking point in their contract talks.

“While some significant issues remain in contention, I am cautiously optimistic that they can be resolved in the upcoming 30-day extension period,” George H. Cohen, director of the Federal Mediation and Conciliation Service, which has overseen the negotiations, said in a statement.