how long a Str can be used in this python code segment?

[MRAB]

Chris Rebert wrote:
> On Mon, Feb 1, 2010 at 1:17 AM, Stephen.Wu <54wutong at gmail.com> wrote:
>> tmp=file.read() (very huge file)
>> if targetStr in tmp:
>>    print "find it"
>> else:
>>    print "not find"
>> file.close()
>>
>> I checked if file.read() is huge to some extend, it doesn't work, but
>> could any give me some certain information on this prolbem?
> 
> If the file's contents is larger than available memory, you'll get a
> MemoryError. To avoid this, you can read the file in by chunks (or if
> applicable, by lines) and see if each chunk/line matches.
> 
If you're processing in chunks then you also need to consider the
possibility that what you're looking for crosses a chunk boundary, of
course. It's an easy case to miss! :-)