1. A computer-implemented method for controlling message flow in a parallel computing system having a plurality of compute nodes, the method comprising: assigning a first set of compute nodes to a first node pool; assigning a first message flow control policy to at least two compute nodes of the first node pool, wherein the first message flow control policy specifies at least one logging activity to be performed by an instance of an application running on each of the at least two compute nodes of the first node pool, and wherein subsequent modifications to the assigned first message flow control policy affect one or more of the at least one logging activities performed by each instance of the application running on the at least two compute nodes; initiating execution of the application on each of the compute nodes in the first node pool; while executing the application on the at least two compute nodes of the first node pool, generating a plurality of logging messages according to the first message flow control policy; and upon determining that two or more of the at least two compute nodes of the first node pool are generating duplicate error messages based on content of the plurality of logging messages: assigning a selected one of the two or more compute nodes to a second node pool; and assigning a second message flow control policy corresponding to the second node pool to the selected compute node, wherein the second message flow control policy is distinct from the first message flow control policy, and wherein logging activity performed by the instance of the application running on the selected compute node is controlled by the second message flow control policy rather than the first message flow control policy.