Thank you for the quick reply. I think I have figured it out. The process I did before that is the Terrain-Correction, and it is due to the external DEM file is very big in Tiff format (almost 6 G). I use the ENVI format instead, then it works. Thank you.
Another question, when I use the python to call the snappy to batch process that data, how could I to release the memory allocated by each product after the processing ? as it occupies almost all my RAM. Thanks again.