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From: Claudiu Nicolaie CISMARU <claudiu@virtuamagic.com>
Organization: virtuaMAGIC
To: python-list@python.org
Subject: Re: File access denied after subprocess completion on Windows platform
Date: Wed, 25 May 2011 11:20:45 +0300
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> There used to be a problem with subprocess fds being held by
> a traceback. IIRC, the problem could be triggered by having
> an except clause around a subprocess call within which something=20
> attempted to, eg,
> remove one of the affected files.

I have no subprocess call.. in this last issue. And I didn't triggered=20
one (disabled the Button that runs the subprocess).

        try:
            for line in t.splitlines():

                [...]

                ret =3D self.downloadFileToDisk(filename, do_rename)

                if not ret:
                    print "DEBUG: Problema la download"
                    raise Exception()

(1)     except Exception as inst:
            print type(inst)
            print inst.args

            self.updateText.emit("EROARE: Eroare la descarcare")
            self.updateStatusBar.emit("EROARE: Eroare la descaracare=20
fisiere")
            return

Where downloadFileToDisk():

    def downloadFileToDisk(self, filename, final_rename=3DTrue):
        dfilename =3D os.path.join(saveBasePATH, filename)
        sfilename =3D dfilename + ".part"

        dfolder =3D os.path.dirname(sfilename)
        if dfolder !=3D "":
            if not os.path.isdir(dfolder):
                os.makedirs(dfolder)

        try:
            fp =3D open(sfilename, "wb")
        except:
            return False

        curl =3D pycurl.Curl()

        curl.setopt(pycurl.URL, baseUpdateURL + "/client/" + filename)
        curl.setopt(pycurl.CONNECTTIMEOUT, 30)
        curl.setopt(pycurl.NOPROGRESS, 0)
        curl.setopt(pycurl.FOLLOWLOCATION, 1)
        curl.setopt(pycurl.MAXREDIRS, 5)
        curl.setopt(pycurl.PROGRESSFUNCTION, self.updateFileProgress)
        curl.setopt(pycurl.WRITEDATA, fp)
        curl.setopt(pycurl.BUFFERSIZE, 4194304)
        curl.setopt(pycurl.NOSIGNAL, 1)
        curl.perform()

        retcode =3D curl.getinfo(pycurl.HTTP_CODE)

        curl.close()

        fp.close()

        if retcode !=3D 200:
(2)         os.unlink(sfilename)
            return False

        self.msleep(10)

        if final_rename:
            os.rename(sfilename, dfilename)

        return True

Without self.msleep(10), (1) catches WindowsError: file access ... blah=20
blah. Maybe at (2) can be an access violation, but it wasn't triggered=20
yet in tests. I will move the sleep after fp.close(). Yes, I know that=20
what it've done with raise Exception() is UGLY, since this program it's=20
more a quick hack solution to a problem :). Anyway the Exception that is=20
catched is not rised by my code (it's a WindowsError).=20

> I'm sorry if that's a bit
> of a woolly description but if you think this might be
> biting you I'll dive in and look at the code. What version
> of Python are you using?

Last 2.7.x. Well, if os.rename is instead a subprocess call, then it's=20
subprocess based. I'm new to Python but 99% I think it's a system call=20
:)

> (That said, the fact that the behaviour varies between faster
> and slower computers makes that cause unlikely. Maybe we're
> back to looking at virus checkers and the like...)

On that virtual machine there is no virus checker. On the faster machine=20
I disabled and closed the antivirus.

=2D-=20
  Claudiu Nicolaie CISMARU
  GNU GPG Key: http://claudiu.targujiu.net/key.gpg
  T: +40 755 135455
  E: claudiu@virtuamagic.com, claudiu.cismaru@gmail.com

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