[ftputil] How to correctlry close a ftp connection

[Yvan Strahm]

On Fri, Dec 12, 2008 at 2:47 PM, Stefan Schwarzer <sschwarzer at sschwarzer.net
> wrote:

> Hi Yvan,
>
> On 2008-12-12 13:40, Yvan Strahm wrote:
> > I get this error:
> >
> > Traceback (most recent call last):
> >   File "./map_taxo.py", line 186, in ?
> >     Download_me(ftp,ftp_dir,file,target)
> >   File "./map_taxo.py", line 95, in Download_me
> >     host=ftputil.FTPHost(ftp,user,password)
> >   File "/usr/lib/python2.4/site-packages/ftputil/ftputil.py", line 136,
> > in __init__
> >     self._session = self._make_session()
> >   File "/usr/lib/python2.4/site-packages/ftputil/ftputil.py", line 174,
> > in _make_session
> >     return ftp_error._try_with_oserror(factory, *args, **kwargs)
> >   File "/usr/lib/python2.4/site-packages/ftputil/ftp_error.py", line 86,
> > in _try_with_oserror
> >     raise PermanentError(obj)
> > ftputil.ftp_error.PermanentError: 530 Sorry, the maximum number clients
> > (32) from your host are already connected.
> > Debugging info: ftputil 2.2.3, Python 2.4.3 (linux2)
>
> Does the FTPHost construction here refer to the first in the try
> clause or the second in the except clause?


the second one in the except


>
>
> > I have a list of file s to be downloaded and open/close for every items.
> > Is it the correct way of doing it?
> >
> > def Download_me(ftp,ftp_dir,file,target):
> >   user = 'anonymous'
> >   password = 'anonymous'
> >   try:
> >     print "CONNECTING TO "+ ftp + ftp_dir+file+"\n"
>
> Which actual values did you use for ftp, ftp_dir, file and
> target which caused the exception, if I may ask?
>

    ftp='ftp.genome.jp'
    ftp_dir='/pub/kegg/genes/organisms_kaas/'
    file='dola/'

tartget=./eukaryotes/vertebrates/fishes/oryzias_latipes_japanese_medaka_/o.latipes.pep



>
> >     host=ftputil.FTPHost(ftp,user,password)
> >     host.chdir(ftp_dir+file)
>
> Does ftp_dir contain a trailing slash here? I'd recommend to use
> FTPHost.path.join(ftp_dir, file) and ftp_dir without a trailing
> slash.
>

sorry I don't use the path.join.function, I should have read the
documentation more seriously ...


> >     names=host.listdir(host.curdir)
> >     for name in names:
> >       if host.path.isfile(name):
> >         p="pep"
> >         m_pep=re.search(p,name)
> >         if m_pep:
> >           returned=name
> >           host.download_if_newer(name,target,'b')
> >     host.close()
> >   except:
>
> I suggest you avoid a bare "except"; use "except
> ftp_error.PermanentError" (or rather the exceptions you actually
> expect). In your current code, _any_ exception would trigger the
> except clause, thus catching exceptions you perhaps don't want to
> be caught.
>
> >     print "could not be dowloaded try KAAS"
> >     ftp='ftp.genome.jp <http://ftp.genome.jp>'
>
> If you use this for the host argument of the FTPHost constructor,
> it will probably fail. Use just the full name of the FTP server
> (ftp.genome.jp), without the part in angle brackets.
>
> >     ftp_dir='/pub/kegg/genes/organisms_kaas/'
> >     print "CONNECTING TO "+ ftp + ftp_dir+file+"\n"
> >     host=ftputil.FTPHost(ftp,user,password)
> >     host.chdir(ftp_dir+file)
> >     names=host.listdir(host.curdir)
> >     for name in names:
> >       if host.path.isfile(name):
> >         p="pep"
> >         m_pep=re.search(p,name)
> >         if m_pep:
> >           returned=name
> >           host.download_if_newer(name,target,'b')
> >     host.close()
>
> Possibly you should put the common parts of the try and except
> clauses into a function.
>
> Regarding the symmetry of the FTPHost construction and calling
> the close method, at first sight this looks well. However, if the
> constructor fails, the close method won't be called, so that may
> be the reason why you exhaust the possible number of connections.
> (On the other hand, this could be a genuine error message if
> enough people are logged into the FTP server at the same time.)
> I think you should use a try ... finally construct:
>
> try:
>    print "CONNECTING TO "+ ftp + ftp_dir+file+"\n"
>    host=ftputil.FTPHost(ftp,user,password)
>     try:
>         host.chdir(ftp_dir+file)
>        names=host.listdir(host.curdir)
>        for name in names:
>            if host.path.isfile(name):
>                p="pep"
>                m_pep=re.search(p,name)
>                if m_pep:
>                    returned=name
>                    host.download_if_newer(name,target,'b')
>     finally:
>        host.close()
> except:
>    ...
>
> In this way, the connection will be closed, whether there's an
> exception or not.
>


Thanks I will try to change the code with all your recommendations.
Thanks a lot for your help and tips

>
> Does that help?
>

yes a lot.

>
> Best regards,
> Stefan
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>


Have a nice week end
Best Regards,
yvan
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