Re:POSIX close(2) is broken
by viraptor on Saturday December 17, 2011 @08:34AM
(#3364198)
If you mean different other languages, that's interesting... Python seems to be completely oblivious to the issue and signals (Modules/_io/fileio.c internal_close() and others). There is SA_RESTART added if possible in Modules/faulthandler.c - but I'm not sure what conditions activate it.
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Yeah. This can be a serious issue, for the record. It is difficult for me to come up with an experience that has made me quite as angry as calling urllib.urlopen().read() in a highly-contended program (Apache2 mpm_worker) and getting an EINTR exception bubbled all the way up to the top... I mean, what did they expect I do: retry the entire HTTP fetch? ;P
I finally switched to mpm_event, which caused me to no longer get signals constantly, but until then I was seriously running a patched copy of Python to work around this issue; an issue, by the way, which was reported at the beginning of 2007, and only fixed midway through 2010. :(
http://bugs.python.org/issue1628205
The general idea, however, is that if you are using a low-level primitive, one that nigh unto maps directly to a system call (as opposed to urlopen ;P), then you actually "want" (supposedly) EINTR to not be handled for you, as it might be your intention to use it to do something valuable (just as you might from a C program).