Patches item #1407135, was opened at 2006-01-16 09:44 Message generated for change (Comment added) made by titty You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1407135&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Library (Lib) Group: Python 2.4 Status: Closed Resolution: Accepted Priority: 5 Submitted By: Ralf Schmitt (titty) Assigned to: Neal Norwitz (nnorwitz) Summary: anonymous mmap Initial Comment: make mmap.mmap(-1, size) map anonymous memory on both windows and unix-like systems. If this goes in, I'll also write some documentation. here's some more reasoning: https://sourceforge.net/tracker/? func=detail&atid=105470&aid=1402308&group_id=5470 ---------------------------------------------------------------------- >Comment By: Ralf Schmitt (titty) Date: 2006-02-05 16:09 Message: Logged In: YES user_id=17929 The manpages for open(2) on FreeBSD 4.11, Ubuntu 5.10 and OpenBSD 3.8 all mention '#include <fcntl.h>' in their synopsis, so I guess it might be a good idea to include it. I ran Lib/test/test_mmap.py for python trunk on FreeBSD, OpenBSD, Ubuntu and Suse8/amd64 with success. That one comment should now read 'maybe define MAP_ANONYMOUS in terms of MAP_ANON'. However, I didn't test 2.4.3... ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2006-02-05 07:01 Message: Logged In: YES user_id=33168 I modified the patch some. Removed include <fcntl.h> since that didn't seem necessary. Changed the #ifdef slightly. Modified comments. I now understand that anonymous memory was allowed on Unix before (in 2.3 and pre 2.4.2). I backported the non-feature enhancements of this patch (not dup()ing -1). So 2.4.3 should work like 2.4.1 and earlier. It would be great if you can test out 2.5 and 2.4.3 from SVN. Committed revision 42244. Committed revision 42245. (2.4) ---------------------------------------------------------------------- Comment By: Ralf Schmitt (titty) Date: 2006-01-18 10:16 Message: Logged In: YES user_id=17929 Thanks for the insight. And yes, I forgot to check that little box. ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2006-01-18 07:24 Message: Logged In: YES user_id=33168 To answer your question: > Aren't the tests being run before release on all major platforms? It's difficult to answer. I think generally the answer is yes, but it all depends on volunteers. We are currently running tests on every checkin: http://www.python.org/dev/buildbot/ for both HEAD and 2.4 branch. BuildBot is a relatively recent addition though. On OS X 10.3, we aren't having a problem with mmap(). Various developers I know use OS X, not sure which versions of OS X though. -- General comments about the patch: For any solution, we should strive to make it available if possible (with reason) on all platforms. We should attempt to have all versions of Python behave similarly. (I'm not trying to imply you aren't working in this direction, it seems like you are.) I only notice one patch attached. Have you been deleting the others or did you forget to check the litle box? ---------------------------------------------------------------------- Comment By: Ralf Schmitt (titty) Date: 2006-01-17 11:34 Message: Logged In: YES user_id=17929 This patch tries to mmap via /dev/zero if neither MAP_ANON nor MAP_ANONYMOUS is defined and handles the case where only MAP_ANONYMOUS is defined. I've added some tests, and found that test_mmap executed mmap(-1, ...), which probably would have crashed the tests running on OS X. Aren't the tests being run before release on all major platforms? ---------------------------------------------------------------------- Comment By: Ralf Schmitt (titty) Date: 2006-01-17 09:59 Message: Logged In: YES user_id=17929 Well, seems like one would also need some special handling for systems only defining one of MAP_ANON/MAP_ANONYOUS: http://www.winehq.org/hypermail/wine-devel/2004/12/0064.html ---------------------------------------------------------------------- Comment By: Ralf Schmitt (titty) Date: 2006-01-17 09:48 Message: Logged In: YES user_id=17929 quoting ubuntu's mmap man page: MAP_ANONYMOUS The mapping is not backed by any file; the fd and offset arguments are ignored. This flag in conjunction with MAP_SHARED is implemented since Linux 2.4. MAP_ANON Alias for MAP_ANONYMOUS. Deprecated. --- On a glibc 2.1 system (once installed with a 2.2 kernel, now running a 2.4 one) the manpage doesn't even mention MAP_ANON(YMOUS). The patch in it's current form will just fail on system's not defining MAP_ANON (i.e. mmap will fail and an exception will be raised). However, according to Stevens 'Advanced Programming in the Unix Environment', chapter 14.9, there are two ways to mmap anonymous memory. The first one works by using MAP_ANON (4.3+BSD), and the second one works by opening /dev/zero and passing that as a filedescriptor to mmap (SVR4). So, I guess all BSD's and newer Linux Systems would work with this version. Anyway I can send another patch handling that case if you like? ---------------------------------------------------------------------- Comment By: Neal Norwitz (nnorwitz) Date: 2006-01-17 06:22 Message: Logged In: YES user_id=33168 In addition to docs, tests will also be necessary before committing. What if fd == -1 and MAP_ANON is not defined? It seems the state could be inconsistent. Shouldn't an exception be raised in this case? ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1407135&group_id=5470 _______________________________________________ Patches mailing list [email protected] http://mail.python.org/mailman/listinfo/patches
