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Re^4: Perl Signals

by afoken (Parson)
on Nov 17, 2011 at 16:51 UTC ( #938648=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Perl Signals
in thread Perl Signals

[...] the requirement to re-install a signal handler is some super ancient (many decades ago) stuff. [...] I would think that the Perl docs should be updated.

So do I.

this while() loop in the reaper is definitely needed

I have no problem with the while loop in the reaper, it is properly explained in perlipc.

On the other hand, so is the problem with old SysV behaviour:

But that will be problematic for the more complicated handlers that need to reinstall themselves. Because Perl's signal mechanism is currently based on the signal(3) function from the C library, you may sometimes be so unfortunate as to run on systems where that function is "broken"; that is, it behaves in the old unreliable SysV way rather than the newer, more reasonable BSD and POSIX fashion. So you'll see defensive people writing signal handlers like this:

I think the paragraph cited above and the two examples following it should be moved into a new section "Signal Handlers on Ancient Systems" ("pre-POSIX systems"?), and be replaced with text and examples that concentrate on handling SIGCHLD / wait / waitpid instead of working around ancient API problems.

Alexander

--
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)


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