A system comprising: an asynchronous packet network; and a synchronous network; and a first cluster of configurable circuits, the first cluster of configurable circuits comprising a plurality of configurable circuits (200, 205) arranged in an array, each configurable circuit in the first cluster of configurable circuits comprising: a configurable computation circuit; a plurality of synchronous network inputs comprising a plurality of input registers; a plurality of synchronous network outputs comprising a plurality of output registers; an asynchronous network input queue coupled to the asynchronous packet network, the asynchronous network input queue storing asynchronous network messages and packets routed on the asynchronous packet network; an asynchronous network output queue coupled to the asynchronous packet network; wherein: the plurality of synchronous network outputs directly coupled over communication lines of the synchronous network to the synchronous network inputs of adjacent configurable circuits of the plurality of configurable circuits to form a synchronous domain pipeline for performance of one or more threads of computation; the system further comprising: a stop signal communication line coupled to each of the configurable circuits of the plurality of configurable circuits; a flow control circuit coupled to the asynchronous network output queue of each configurable circuit in the first cluster of configurable circuits, the flow control circuit adapted to generate a stop signal on the stop signal communication line when a predetermined threshold has been reached in the asynchronous network output queue of any configurable circuit in the first cluster of configurable circuits; and wherein, in response to receipt of the stop signal each configurable circuit in the first cluster of configurable circuits is configured to: pause the synchronous domain pipeline while allowing the asynchronous network input queue to receive asynchronous network messages. an asynchronous packet network; and a synchronous network; and a first cluster of configurable circuits, the first cluster of configurable circuits comprising a plurality of configurable circuits (200, 205) arranged in an array, each configurable circuit in the first cluster of configurable circuits comprising: a configurable computation circuit; a plurality of synchronous network inputs comprising a plurality of input registers; a plurality of synchronous network outputs comprising a plurality of output registers; an asynchronous network input queue coupled to the asynchronous packet network, the asynchronous network input queue storing asynchronous network messages and packets routed on the asynchronous packet network; an asynchronous network output queue coupled to the asynchronous packet network; wherein: the plurality of synchronous network outputs directly coupled over communication lines of the synchronous network to the synchronous network inputs of adjacent configurable circuits of the plurality of configurable circuits to form a synchronous domain pipeline for performance of one or more threads of computation; the system further comprising: a stop signal communication line coupled to each of the configurable circuits of the plurality of configurable circuits; a flow control circuit coupled to the asynchronous network output queue of each configurable circuit in the first cluster of configurable circuits, the flow control circuit adapted to generate a stop signal on the stop signal communication line when a predetermined threshold has been reached in the asynchronous network output queue of any configurable circuit in the first cluster of configurable circuits; and wherein, in response to receipt of the stop signal each configurable circuit in the first cluster of configurable circuits is configured to: pause the synchronous domain pipeline while allowing the asynchronous network input queue to receive asynchronous network messages. a stop signal communication line coupled to each of the configurable circuits of the plurality of configurable circuits; a flow control circuit coupled to the asynchronous network output queue of each configurable circuit in the first cluster of configurable circuits, the flow control circuit adapted to generate a stop signal on the stop signal communication line when a predetermined threshold has been reached in the asynchronous network output queue of any configurable circuit in the first cluster of configurable circuits; and wherein, in response to receipt of the stop signal each configurable circuit in the first cluster of configurable circuits is configured to: pause the synchronous domain pipeline while allowing the asynchronous network input queue to receive asynchronous network messages.