Flushing control within a multi-threaded processor

A data processing apparatus 2 performs multi-threaded processing using the processing pipeline 6, 8, 10, 12, 14, 16, 18. Flush control circuitry 30 is responsive to multiple different types of flush trigger. Different types of flush trigger result in different sets of state being flushed for the thread which resulted in the flush trigger with state for other thread not being flushed. For example, a relatively low latency stall may result in flushing back to a first flush point whereas a longer latency stall results in flushing back to a second flush point and the loss of more state data. The data flushed back to the first flushed point may be a subset of the data flushed back to the second flush point.