1. A method of processing a client-initiated request, performed by a respective server system having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective server system to perform the method, the method comprising: receiving, from a client system, a respective request including server identifiers for one or more other server systems distinct from the respective server system; after receiving the respective request, determining whether at least a first predefined number of the one or more other server systems have a predefined task-processing status for the respective request indicating that the other server systems have undertaken performance of the respective task-processing operation for the respective request; in accordance with a determination that less than the first predefined number of the one or more other server systems have the predefined task-processing status for the respective request: sending a processing-status message to one or more the other server systems indicating that the respective server system has undertaken performance of the respective task-processing operation for the respective request; and performing the respective task-processing operation; upon completing the task-processing of the respective request: determining whether a second predefined number of the other server systems have undertaken responding to the respective request; and in accordance with a determination that at least the second predefined number of the one or more other server systems have undertaken responding to the respective request, foregoing sending a result of the processing to the client system.