python: what happens to opened file if i quit before it is closed?

Question

i am opening a csv file:

def get_file(start_file): #opens original file, reads it to array
  with open(start_file,'rb') as f:
    data=list(csv.reader(f))
    header=data[0]
    counter=collections.defaultdict(int)
    for row in data:
      counter[row[10]]+=1
  return (data,counter,header)

does the file stay in memory if i quit the program inside the WITH loop?

what happens to the variables in general inside the program when i quit the program without setting all variables to NULL?

Answer 1

The operating system will automatically close any open file descriptors when your process terminates.

File data stored in memory (e.g. variables, Python buffers) will be lost. Data buffered in the operating system may be flushed to disk when the file is implicitly closed (checking the exact semantics of in-kernel dirty-buffers here would be educational, though you should not rely on it).

Your variables cease to exist when your process terminates.