1. A method of data communications in a parallel active messaging interface (‘PAMI’) of a parallel computer, the parallel computer comprising: a plurality of compute nodes that execute a parallel application, each compute node comprising a plurality of computer processors including a plurality of application processors that execute the parallel application and at least one management processor dedicated to gathering information regarding data communications, and the PAMI, the PAMI comprising data communications endpoints, each endpoint comprising a specification of data communications parameters for a thread of execution on a compute node, including specifications of a client, a context, and a task, the compute nodes and the endpoints coupled for data communications through the PAMI and through data communications resources, the method comprising: gathering by the management processor call site statistics describing data communications resulting from execution through the PAMI of data communications instructions; and identifying through the PAMI by the parallel application in dependence upon the call cite statistics a data communications algorithm for use in executing through the PAMI a data communications instruction at a call site in the parallel application.