what happens when the file begin read is too big for all lines to be read with "readlines()"

[Ross Reyes]

HI -
Sorry for maybe a too simple a question but I googled and also checked my 
reference O'Reilly Learning Python
book and I did not find a satisfactory answer.

When I use readlines, what happens if the number of lines is huge?    I have 
a very big file (4GB) I want to
read in, but I'm sure there must be some limitation to readlines and I'd 
like to know how it is handled by python.
I am using it like this:
slines = infile.readlines() # reads all lines into a list of strings called 
"slines"

Thanks for anyone who knows the answer to this one.