Re: [Jython-users] print >> is slow!!

[Patrick C. <pat...@ya...>]

http://sourceforge.net/tracker/?group_id=12867&atid=112867&func=detail&aid=674932


--- Todd Moyer <tm...@in...> wrote:

> 
> I spent a bit of time digging into the Jython source
> to see if there was 
> an obvious explanation.  It seems about 75% of the
> time with "print 
>  >>output" is related to the FixedFileWrapper that
> the output file is 
> wrapped in for every print call.  Just as an
> experiment, I tried 
> allowing the file to default to stdout, as in "print
> 'test'", 
> significantly reducing the time.  It is still a lot
> slower than 
> "output.write ('test')" though.  Interesting find,
> Kent.
> 
> As far as writing critical code in Java, it's a nice
> option to have. 
> However, I rarely find I need to resort to it. 
> Because I can write 
> Jython much faster than Java, I find spending some
> of that saved time 
> tuning the algoriths nearly always yields acceptable
> performance. 
> Careless algoritms can sink code written in any
> language, and often does.
> 
> Cheers,
> Todd Moyer
> 
> 
> Alex Greif wrote:
> 
> > As I understand the Jython philosophy, performance
> critical parts
> > should be better implemented in java.
> > 
> > Alex.
> > 
> > 
> > On Wed, 23 Mar 2005 13:43:07 -0800 (PST), Patrick
> Chamberlain
> > <pat...@ya...> wrote:
> > 
> >>I've seen that before. I think it's a known bug.
> >>
> >>The workaround I use is to use a Java way to print
> >>instead such as a FileOutputStream.
> >>
> >>Patrick
> >>--- Kent Johnson <ke...@td...> wrote:
> >>
> >>>I just tracked down a huge performance problem in
> my
> >>>app to use of print >> output. My program was
> >>>taking five seconds to output a 200 line, 5Kb
> file
> >>>(ouch!)
> >>>
> >>>Here is a program that shows the problem:
> >>>
> >>># FileWriteTest.py
> >>>from java.lang.System import currentTimeMillis
> >>>
> >>>start = currentTimeMillis()
> >>>
> >>>output = open('junk1', 'w')
> >>>for i in range(100):
> >>>     print >>output, 'test'
> >>>output.close()
> >>>
> >>>elapsed = currentTimeMillis() - start
> >>>print 'Using print >>', elapsed
> >>>
> >>>start = currentTimeMillis()
> >>>
> >>>output = open('junk2', 'w')
> >>>for i in range(100):
> >>>     output.write('test')
> >>>     output.write('\n')
> >>>output.close()
> >>>
> >>>elapsed = currentTimeMillis() - start
> >>>print 'Using write   ', elapsed
> >>>
> >>>###
> >>>
> >>>On my computer the output is
> >>>Using print >> 1382
> >>>Using write    30
> >>>
> >>>so output using print >> takes about 40 times as
> >>>long as the same thing with write()!
> >>>
> >>>I'm not going to take this any further, I'm
> >>>reporting it to help others avoid the same hole,
> and
> >>>in
> >>>hopes that someone might fix this going forward
> :-)
> >>>
> >>>Kent
> >>>
> >>>
> >>>
> >>>
> >>
>
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> > 
> >
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