Hi all, For the following code I want to stop early completing processes and wait for the others at the point with (world.barrier)(); statement. But the problem is stop- and stop+ do interleave. Am I doing something wrong with the synchronization, or there is something wrong with my code? if (world.rank() == MASTER){ m_mySize = n / world.size() + n % world.size(); w_mySize = n / world.size(); for(int p = 1; p < world.size(); p++){ world.send(p, 1, w_mySize); world.send(p, 2, n); } relMyValues = new possibleClause[w_mySize]; scatter(world, pC, relMyValues, w_mySize, 0); } else{ world.recv(0, 1, w_mySize); relMyValues = new possibleClause[w_mySize]; scatter(world, pC, relMyValues, w_mySize, 0); } for(i = 0; i < w_mySize; i++){ //do something } cout << world.rank() << " stop - " << world.rank() << endl; (world.barrier)(); cout << world.rank() << " stop + " << world.rank() << endl; if (world.rank() == MASTER){ relAllValues = new possibleClause[n - n % world.size()]; gather(world, relMyValues, w_mySize, relAllValues, 0); } else{ world.recv(0, 2, n); gather(world, relMyValues, w_mySize, relAllValues, 0); }