Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media for performing preflight checks of a distributed computing system, are described. In one aspect, a method includes assigning a computing workload to a first subset of hardware accelerator machines each having one or more hardware accelerators. A preflight check on the first subset is performed before performing the computing workload to verify the functionality of each machine in the first subset. For each hardware accelerator machine of the first subset, a program code package is installed, including a task action based at least in part on characteristics of the computing workload. The task action including a sequence of operations is performed on the hardware accelerator machine to determine whether the task action fails. Whenever the task action fails, the computing workload is re-assigned to a second subset of hardware accelerator machines different from the first subset.