mike na mk-sys.cz
Pátek Březen 10 15:20:48 CET 2006
On Fri, Mar 10, 2006 at 01:41:36PM +0100, Ing. Pavel PaJaSoft Janoušek wrote:
> > Protože by se mu v systému hromadily zombie.
> Ono je to ještě horší - viz man 2 signal: According to POSIX
> (220.127.116.11) it is unspecified what happens when SIGCHLD is set to
> SIG_IGN. Here the BSD and SYSV behaviours differ, causing BSD
> software that sets the action for SIGCHLD to SIG_IGN to fail on
Tak jsem našel ještě něco jiného ve waitpid(2):
POSIX.1-2001 specifies that if the disposition of SIGCHLD is set
to SIG_IGN or the SA_NOCLDWAIT flag is set for SIGCHLD (see
sigaction(2)), then children that terminate do not become zombies and
a call to wait() or waitpid() will block until all children have
terminated, and then fail with errno set to ECHILD. (The original
POSIX standard left the behaviour of setting SIGCHLD to SIG_IGN
unspecified.) Linux 2.6 con- forms to this specification.
However, Linux 2.4 (and earlier) does not: if a wait() or waitpid()
call is made while SIGCHLD is being ignored, the call behaves
just as though SIGCHLD were not being ignored, that is, the call
blocks until the next child terminates and then returns the process
ID and status of that child.
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