ah this seems to be a version of the problem Error: file with ID: X not found rearing its ugly head again. Just this time it was printing as fast as possible in blocks like:
E0420 21:29:01.775426 20 log.go:32] Unable to read: Key: [0 0 21 100 97 116 97 45 105 110 115 105 103 104 116 45 101 110 103 46 116 121 112 101 2 2 69 110 116 105 116 121], Version : 52719241, meta: 70, userMeta: 8 Error: file with ID: 791 not found
E0420 21:29:01.775491 20 log.go:32] Key: [0 0 21 100 97 116 97 45 105 110 115 105 103 104 116 45 101 110 103 46 116 121 112 101 2 2 69 110 116 105 116 121], Version : 52721774, meta: 64, userMeta: 4 valuePointer: {Fid:0 Len:0 Offset:0}
E0420 21:29:01.775502 20 log.go:32] Key: [0 0 21 100 97 116 97 45 105 110 115 105 103 104 116 45 101 110 103 46 116 121 112 101 2 2 69 110 116 105 116 121], Version : 52721607, meta: 64, userMeta: 4 valuePointer: {Fid:0 Len:0 Offset:0}
and I missed the first of the block.