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Hi List,
regarding the flat ndo2db init script with it's tough "killall
ndo2db..." I reviewed the signal processing in ndo2db.
Intro:
As we know ndo2db forks first to become a daemon, no problem up to here,
and forks again for each client connection.
Each client connection has the daemon as session leader but if we send
this leader a SIGTERM the parent process is exiting, deleting the
socket, cleaning up and 'over and out'.
Bad thing: The forked connection child is still alive, hanging around in
read() from the (non existing) socket descriptor.
Possible Solution:
kill(0,sig);
kill(0,SIGNAL) should send the SIGNAL to the complete process group, the
childs do already recognize SIGTERM resulting in _exit(0).
The existing parent sighandler for SIGCHLD does a waitpid for the childs
and in my opinion the world is nice so far.
I already tested the attached patch and it's working fine so far, I just
want to see if there are better ways to handling those parent/child signals.
Regards,
Hendrik
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Content-Type: text/x-patch;
name="ndo2db-fix-child-signals.patch"
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filename="ndo2db-fix-child-signals.patch"
--- a/module/idoutils/src/ido2db.c
+++ b/module/idoutils/src/ido2db.c
@@ -708,11 +708,19 @@ int ndo2db_cleanup_socket(void){
void ndo2db_parent_sighandler(int sig){
- /* cleanup children that exit, so we don't have zombies */
- if(sig==SIGCHLD){
- while (waitpid(-1, NULL, WNOHANG) > 0);
+ switch (sig){
+ case SIGTERM:
+ /* forward signal to all members of this group of processes */
+ kill(0, sig);
+ break;
+ case SIGCHLD:
+ /* cleanup children that exit, so we don't have zombies */
+ while(waitpid(-1,NULL,WNOHANG)>0);
return;
- }
+
+ default:
+ printf("Caught the Signal '%d' but don't care about this.\n", sig);
+ }
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Original poster: [email protected]