What would cause opencv_traincascade to never finish and/or freeze? - opencv

Question

I'm trying to run my first opencv training set and I'm not convinced that opencv_traincascade is making progress. For my training set I have 9 positive images and 10 negative images. To create samples I have used
opencv_createsamples -vec box.vec -w 44 -h 50
and for my training set I run
opencv_traincascade -data data -vec box.vec -bg bg.txt -numPos 8 -numNeg 10 -numStages 2 -w 44 -h 50 -featureType LBP
All positive and negative images are 44x50 and here is the output of both tools
opencv_createsamples
Info file name: (NULL)
Img file name: (NULL)
Vec file name: box.vec
BG file name: (NULL)
Num: 1000
BG color: 0
BG threshold: 80
Invert: FALSE
Max intensity deviation: 40
Max x angle: 1.1
Max y angle: 1.1
Max z angle: 0.5
Show samples: FALSE
Original image will be scaled to:
Width: $backgroundWidth / 44
Height: $backgroundHeight / 50
opencv_traincascade
PARAMETERS:
cascadeDirName: data
vecFileName: box.vec
bgFileName: bg.txt
numPos: 8
numNeg: 10
numStages: 1
precalcValBufSize[Mb] : 1024
precalcIdxBufSize[Mb] : 1024
acceptanceRatioBreakValue : -1
stageType: BOOST
featureType: LBP
sampleWidth: 44
sampleHeight: 50
boostType: GAB
minHitRate: 0.995
maxFalseAlarmRate: 0.5
weightTrimRate: 0.95
maxDepth: 1
maxWeakCount: 100
===== TRAINING 0-stage =====
<BEGIN
POS count : consumed 8 : 8
NEG count : acceptanceRatio 10 : 1
The training never shows any other output even after many hours of run time. I see no data in my data directory. Clearly i'm doing something wrong and I'd love to know what it is.