Python 3 read() function

[Terry Reedy]

Дамјан Георгиевски wrote:
>> I don't think it matters.  Here's a quick comparison between 2.5 and
>> 3.0 on a relatively small 17 meg file:
>>
>> C:\>c:\Python30\python -m timeit -n 1
>> "open('C:\\work\\temp\\bppd_vsub.csv', 'rb').read()"
>> 1 loops, best of 3: 36.8 sec per loop
>>
>> C:\>c:\Python25\python -m timeit -n 1
>> "open('C:\\work\\temp\\bppd_vsub.csv', 'rb').read()"
>> 1 loops, best of 3: 33 msec per loop
>>
>> That's 3 orders of magnitude slower on python3.0!
> 
> Isn't this because you have the file cached in memory on the second run? 

In my test, I read Python25.chm with 2.5 and Python30.chm with 3.0.

Rereading Python30.chm without closing *is* much faster.
 >>> f=open('Doc/Python30.chm','rb')
 >>> d=f.read()
 >>> d=f.read()
 >>> d=f.read()
Closing, reopening, and rereading is slower.