spawn

QNX Newsgroups (Archives) qdn.public.qnx4
1

I have a process spawning children with spawnl(P_NOWAIT, …) It seems that
the parent does not receive any SIGCHILD upon the cildrens’ death. I’d
like to receive that signal. What did I do wrong? Does P_NOWAIT result
in no SIGCHILDs being sent? The signal handler works ok.

Thanks / Tom

2

Tomas H?gstr?m <tomas@scandicraft.se> wrote:

I have a process spawning children with spawnl(P_NOWAIT, …) It seems that
the parent does not receive any SIGCHILD upon the cildrens’ death. I’d
like to receive that signal. What did I do wrong? Does P_NOWAIT result
in no SIGCHILDs being sent? The signal handler works ok.

signal(SIGCHLD, SIG_IGN ) will cause no SIGCHLD’s to be generated, but
you haven’t likely done that as you have a handler.

Have you passed P_NOWAITO instead of P_NOWAIT? That will also cause this.

Have you messed with the qnx_spawn_options global, and possibly set
the _SPAWN_NOZOMBIE in the flags?

(To check, you could always print out the flags entry just before your
spawn call.)

After the child has started, have you tried a “sin fl” to see if the
no zombie bit is set?

-David

3

Previously, Tomas Högström wrote in qdn.public.qnx4:

I have a process spawning children with spawnl(P_NOWAIT, …) It seems that
the parent does not receive any SIGCHILD upon the cildrens’ death. I’d
like to receive that signal. What did I do wrong? Does P_NOWAIT result
in no SIGCHILDs being sent? The signal handler works ok.

there used to be a problem in the C librarys where SIGCHILD was disabled by accident.
Do you have the latest compiler update?

Thanks / Tom

4

Thanks. I found the error, I had forgotten to rename P_NOWAITO to P_NOWAIT
in one place…

/ Tom

David Gibbs wrote:

Tomas H?gstr?m <> tomas@scandicraft.se> > wrote:
I have a process spawning children with spawnl(P_NOWAIT, …) It seems that
the parent does not receive any SIGCHILD upon the cildrens’ death. I’d
like to receive that signal. What did I do wrong? Does P_NOWAIT result
in no SIGCHILDs being sent? The signal handler works ok.

signal(SIGCHLD, SIG_IGN ) will cause no SIGCHLD’s to be generated, but
you haven’t likely done that as you have a handler.

Have you passed P_NOWAITO instead of P_NOWAIT? That will also cause this.

Have you messed with the qnx_spawn_options global, and possibly set
the _SPAWN_NOZOMBIE in the flags?

(To check, you could always print out the flags entry just before your
spawn call.)

After the child has started, have you tried a “sin fl” to see if the
no zombie bit is set?

-David

5

Horst Hannappel <Horst.Hannappel@mbs-software.de> wrote:

Previously, Tomas Hogstrom wrote in qdn.public.qnx4:
I have a process spawning children with spawnl(P_NOWAIT, …) It seems that
the parent does not receive any SIGCHILD upon the cildrens’ death. I’d
like to receive that signal. What did I do wrong? Does P_NOWAIT result
in no SIGCHILDs being sent? The signal handler works ok.


there used to be a problem in the C librarys where SIGCHILD was disabled
by accident.

I should have remembered that one… I fixed the library code. It whappened
if you did a spawn() with P_WAIT, if I remember correctly.

-David