Re: [Jython-users] File write and read

[Jeff E. <jem...@fr...>]

Because it does a physical I/O operation for every byte.
You need to wrap the file streams with buffered streams,
for example:

bi = BufferedInputStream(FileInputStream(File(filename)))


Lauri Lehtinen wrote:
> Setting to use the binary mode worked!
> 
> Does any one know why java variant of this in jython performs very poorly?
> 
> Here the basic java variant:
> ---
> from java.net import *
> from java.io import *
> def copy(filename):
>    bi = FileInputStream(File(filename))
>    bo = FileOutputStream(File(filename+".copy"))
>    b = [1000000]
>    while 1:
>        l = bi.read(b)
>        if l == -1:
>            break
>        bo.write(b)              bo.close()
>    bi.close()
>    return 1
>           if __name__ == "__main__":          i = raw_input("Give file:")
>    copy(i)
> ---
> That berforms only about 10kB/s, here one that uses buffers and performs 
> better:
> ---
> from java.net import *
> from java.io import *
> def copy(filename):
>    bi = BufferedInputStream(FileInputStream(File(filename)))
>    bo = BufferedOutputStream(FileOutputStream(File(filename+".copy")))
>    while 1:
>        l = bi.read()
>        if l == -1:
>            break
>        bo.write(l)              bo.close()
>    bi.close()
>    return 1
>           if __name__ == "__main__":          i = raw_input("Give file:")
>    copy(i)
> ---
> This performs about 600kB/s what isn't good at all, that should be much 
> better. I tried also by using static buffer size but that performed even 
> poorly for some reason. Why the performance is so bad?
> 
> Sincerely,
> Lauri Lehtinen
> 
> Kent Johnson wrote:
> 
>> Lauri Lehtinen wrote:
>>
>>> Hi,
>>>
>>> I just noticed this, when I have this kind of code:
>>> ---
>>> def copyFile(filename):
>>>    bi = open(filename)
>>>    bo = open(filename+'.copy', 'w')
>>>    b = 1000000
>>>    while 1:
>>>        l = bi.read(b)
>>>        if len(l) == 0:
>>>            break
>>>        bo.write(l)
>>>    bo.close()
>>>    bi.close()
>>>    return 1
>>>           i = raw_input("Give file:")
>>> copyFile(i)
>>> ---
>>> and e.g. copy mp3 file with it the .copy mp3 file is somehow mixed 
>>> and not working as it should, but when I run this with plain python 
>>> it works just as it should. How to fix or workaround this? Is thus 
>>> known bug?
>>
>>
>>
>> Maybe you need to use binary mode?
>>    bi = open(filename, 'b')
>>    bo = open(filename+'.copy', 'wb')
>>
>> How do the two files differ?
>>
>> Kent
>>
>>>
>>> I have tried to make the same using java's FileInputStream and 
>>> FileOutputStream but then the performance is then very bad (about 
>>> 500kB/s). Is that also known issue?
>>>
>>> Sincerely,
>>> Lauri Lehtinen
>>>
>>>
>>>
>>> -------------------------------------------------------
>>> SF email is sponsored by - The IT Product Guide
>>> Read honest & candid reviews on hundreds of IT Products from real users.
>>> Discover which products truly live up to the hype. Start reading now.
>>> http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
>>> _______________________________________________
>>> Jython-users mailing list
>>> Jyt...@li...
>>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>>
>>
>>
>>
>>
>> -------------------------------------------------------
>> SF email is sponsored by - The IT Product Guide
>> Read honest & candid reviews on hundreds of IT Products from real users.
>> Discover which products truly live up to the hype. Start reading now.
>> http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
>> _______________________________________________
>> Jython-users mailing list
>> Jyt...@li...
>> https://lists.sourceforge.net/lists/listinfo/jython-users
>>
>>
>>
> 
> 
> 
> -------------------------------------------------------
> SF email is sponsored by - The IT Product Guide
> Read honest & candid reviews on hundreds of IT Products from real users.
> Discover which products truly live up to the hype. Start reading now.
> http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
> _______________________________________________
> Jython-users mailing list
> Jyt...@li...
> https://lists.sourceforge.net/lists/listinfo/jython-users