On Wed, Jul 29, 2009 at 03:32:28PM +0800, Haojun Bao wrote: >Christopher Faylor <cgf-use-the-mailinglist-ple...@cygwin.com> writes: > >> On Tue, Jul 28, 2009 at 10:52:44AM +0800, Haojun Bao wrote: >>>I have debugged it again, and I think I have more clue. I have read the >>>how-cygheap-works.txt, and this might be a known problem. >>> >>>It's because the cygheap space has been used up. With Procexp, I can see >>>cygwin1.dll is based 0x61000000, with size 0x300000 (3M). When segfault >>>is about to happen, cygheap_max is 0x6164e924, and the _csbrk is called >>>with a increase of >>> (gdb) p sbs >>> $16 = 65544 >>>This will increase cyghead to 0x6165e92c, but from Proxexp I can see >>>cygncurses-9.dll is based at 0x61650000. >>> >>>Besides, this code snippet from pipe.cc fhandler_pipe::create didn't >>>check for NULL pointer, and directly caused the segfault. >>> >>> fhs[0] = (fhandler_pipe *) build_fh_dev (*piper_dev); >>> fhs[1] = (fhandler_pipe *) build_fh_dev (*pipew_dev); >>> >>>//bhj: we should check NULL here. >> >> Not necessarily. We don't expect these functions to return NULL. It >> would be interesting to know how many fds are open at this point. If it >> is a large number then maybe we have to start enforcing an fd max. If >> it is a "small" number then something is wrong and we're allocating too >> much of the cygheap. The cygheap was always supposed to be relatively >> small. Maybe we're abusing it too much in 1.7. > >There are quite some fds. In start-process, emacs will allocate 1 PTY >and 1 pipe for each process it starts.
Yes, I assumed that there were a bunch of fds but I was looking for an exact number rather than "quite some". I can't give exact details about how to find the number now but I thought that since you were looking at the code it wouldn't be too hard to figure this value out. Anyway, Corinna has a stopgap fix for this which will probably show up in a 1.7.0-* release sometime soon. cgf -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
