Robert Kern wrote: > On 2009-11-12 12:05 PM, Andrew Straw wrote: > >> Celil Rufat wrote: >> >>> I just installed matplotlib on Snow Leopard 10.6 with the Qt4 backend >>> (via macports). However, when I try one of the Qt4 examles: >>> >>> python >>> /opt/local/share/py26-matplotlib/examples/user_interfaces/embedding_in_qt4.py >>> >>> >>> IOError: [Errno 4] Interrupted system call >>> >>> Any ideas on what could be causing this? >>> >> Out of curiosity, does anyone know where the signal interrupting the >> system call is originating? Is this a standard communication mechanism >> within Qt4? (I have never used Qt4.) I'm interested in knowing about OSS >> that use signals as a means of across-thread or across-process >> communication. >> > > This problem arises when signal handlers are installed, not necessarily when > a > signal itself is sent (dtrace doesn't detect any). Hmm, but a system call isn't going to get interrupted and return EINTR by any means other than a signal. So the OP must have had a signal interrupting the call and it must have come from somewhere. Or... am I wrong?
> PyQt4 doesn't do it, but I > think something in QApplication does. I really don't know what, though. Here > are > the files that call signal(3) or sigaction(3): > > ./src/3rdparty/freetype/src/tools/ftrandom/ftrandom.c > ./src/3rdparty/phonon/qt7/quicktimevideoplayer.mm > ./src/3rdparty/sqlite/shell.c > ./src/3rdparty/webkit/JavaScriptCore/jsc.cpp > ./src/corelib/io/qfilesystemwatcher_dnotify.cpp > ./src/corelib/io/qprocess_unix.cpp > ./src/corelib/kernel/qcrashhandler.cpp > ./src/corelib/kernel/qeventdispatcher_unix.cpp > ./src/gui/embedded/qwindowsystem_qws.cpp > ./src/gui/embedded/qwssignalhandler.cpp > ./tools/qvfb/main.cpp > > It's not obvious to me that any of these are activated on OS X (the > qcrashhandler.cpp file is intriguing, but it only seems to be used in the X11 > QApplication). dtrace doesn't actually show either signal(3) or sigaction(3) > being called at all. Actually, running a program under dtrace while probing > those functions makes the problem go away. Sometimes. > Ahh, a fun Heisenbug. OK, well if I decide to look for programs that use signals as a means of communication, I'll investigate Qt further. I asked because there's a proprietary library I'm forced to use that does communicate internally with signals. It's a real pain, however, because it means anything else in that process also gets hit with signals and so system calls must be EINTR safe. -Andrew ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
