In the computation of E and the CIPSI selection, each task corresponds to the computation of one ε J or ε K in Eq. ( ), together with the selection of the associated external determinants. To establish the list of tasks, the Monte Carlo sampling is pre-computed on the master node. We associate to each task the number of drawn Monte Carlo samples such that running averages can be computed when the results of the tasks have been received by the collector thread. When the convergence criterion is reached, the task queue is emptied and the collector waits for all the running tasks to terminate.