Date: Fri, 12 Apr 2019 10:45:31 +0300 From: Alexander Zagrebin <alex@zagrebin.ru> To: freebsd-ports@freebsd.org Subject: Re: python 3 subprocess performance Message-ID: <20190412104531.7b492a3c@vm2.home.zagrebin.ru> In-Reply-To: <CAAWYfq2P5QsSbc2bzQauApF6=ijQYpKCb2HQ1jy-4dNZCOB_=g@mail.gmail.com> References: <20190411161649.1b740d21@vm2.home.zagrebin.ru> <8f3f8413-60f2-bb03-a6b4-4f6364cdc3df@rlwinm.de> <20190411143926.5rg4jskmodt4shhi@laparbeit> <9729db47-12c4-caf4-cdcf-1913dab73c8e@rlwinm.de> <20190412101012.4142854f@vm2.home.zagrebin.ru> <CAAWYfq2P5QsSbc2bzQauApF6=ijQYpKCb2HQ1jy-4dNZCOB_=g@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
В Fri, 12 Apr 2019 09:36:13 +0200 Dima Pasechnik <dimpase+freebsd@gmail.com> пишет: > On Fri, Apr 12, 2019 at 9:11 AM Alexander Zagrebin <alex@zagrebin.ru> > wrote: > > > > В Thu, 11 Apr 2019 17:32:42 +0200 > > Jan Bramkamp <crest@rlwinm.de> пишет: > > > > > The reason is that that python does something stupid (tm). It > > > tries to close all file descriptors (except a few whitelisted > > > ones) up to the maximum file descriptor number. It does this by > > > asking the kernel for the maximum possible number and closing > > > everything it doesn't want to keep. Some time later someone came > > > up with an optimization (read the open file descriptors > > > from /dev/fd). All of this pain and suffering is caused by good > > > old Ulrich Drepper braindamage: > > > https://sourceware.org/bugzilla/show_bug.cgi?id=10353. > > > > > > Most Linux distros have lower default file descriptor limits than > > > FreeBSD making this workaround less painful. The correct solution > > > would be to teach python3 about closefrom(2). > > > > Thank you for hint and testing! > > > > Indeed the problem is in closing more than 400,000 file descriptors > > in loop. It seems that all current versions of Python are affected. > > Python2 uses False as default value for the close_fds parameter of > > the Popen constructor, so this issue is mostly not visible. > > Python3 has changed this default to True. > > > > As Jan Bramkamp suggested, I've wrote simple patch to fix an issue > > (see attached file). It seems the problem has gone. > > The attachment has been stripped out. Could you paste the diff into > the message? Yes, sure. --- Modules/_posixsubprocess.c.orig 2018-12-24 00:37:14.000000000 +0300 +++ Modules/_posixsubprocess.c 2019-04-12 09:25:21.549389000 +0300 @@ -235,11 +235,15 @@ _close_fds_by_brute_force(long start_fd, } start_fd = keep_fd + 1; } +#if defined(__FreeBSD__) + closefrom(start_fd); +#else if (start_fd <= end_fd) { for (fd_num = start_fd; fd_num < end_fd; ++fd_num) { close(fd_num); } } +#endif } > If this is a Python issue, shouldn't this be reported upstream, on > https://bugs.python.org ? May be. Rather, it is a FreeBSD-specific optimization. -- Alexander Zagrebin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20190412104531.7b492a3c>