1. A method of computing a model of program execution behavior, comprising: assigning, using a hardware processor, a first sequence of function calls to a first computing device of an application community and a second sequence of function calls to a second computing device of the application community, wherein the application community includes a plurality of computing devices running a program that executes the first sequence of function calls and the second sequence of function calls; receiving a first model of the first sequence of function calls from the first computing device and a second model of the second sequence of function calls from the second computing device; generating a combined model that combines at least a portion of the first model and at least a portion of the second model; and notifying at least one of the plurality of computing devices in the application community of an anomalous function call that was detected using the combined model.