Re: [Jython-users] File write and read

[Lauri L. <pu...@su...>]

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
>>
>>
>>
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>
>
>
>
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