Le Mon, 29 Apr 2013 16:42:38 +0200, Armin Rigo <ar...@tunes.org> a écrit : > Hi Nikolaus, > > On Sat, Apr 27, 2013 at 4:39 AM, Nikolaus Rath <nikol...@rath.org> > wrote: > > It's indeed very informative, but it doesn't fully address the > > question because of the _pyio module which certainly can't use any > > custom C code. Does that mean that when I'm using x = > > _pyio.BufferedWriter(), I could loose data in the write buffer when > > the interpreter exits without me calling x.close(), but when using > > x = io.BufferedWriter(), the buffer is guaranteed to get flushed? > > I actually described the behavior of CPython 2 while not realizing > that CPython 3 silently dropped this guarantee.
It is dropped in the case of reference cycles, since there's no general way to decide in which order the tp_clear calls have to be done. Thus in the following layered situation: a TextIOWrapper on top of a BufferedWriter on top of a FileIO, if BufferedWriter.tp_clear is called first, it will flush and then close itself, closing the FileIO at the same time, and when TextIOWrapper.tp_clear will be called it will be too late to flush its own buffer. (I have to investigate a bit to confirm it is what happens) I will try to think of a scheme to make flushing more reliable, but nothing springs to my mind right now. Note that the issue of how reference cycles involving globals are collected at interpreter shutdown is an orthogonal one, as pointed out in http://bugs.python.org/issue17852. Regards Antoine. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
