1. A computer-implemented method for identifying messaging completion on a parallel computer, the parallel computer comprising a plurality of compute nodes, the compute nodes coupled for data communications by at least two independent data communications networks including a binary tree data communications network optimal for collective operations that organizes the nodes as a tree and a torus data communications network optimal for point to point operations that organizes the nodes as a torus, the method comprising: reading all counters at each node of the torus data communications network; calculating at each node a current node value in dependence upon the values read from the counters at each node; and determining for all nodes whether the current node value for each node is the same as at least one previously calculated node value for each node; and if the current node value is the same as the previously calculated node value for all nodes of the torus data communications network, determining that messaging is complete; and if the current node value is not the same as the previously calculated node value for all nodes of the torus data communications network, determining that messaging is currently incomplete.