patch to force cyrus to reload its configuration in a more rigorous way

Alain Spineux aspineux at gmail.com
Sun Apr 6 11:28:27 EDT 2008


I opened a new bug on bugzilla.

https://bugzilla.andrew.cmu.edu/show_bug.cgi?id=2987

Alain

On 4/2/08, Alain Spineux <aspineux at gmail.com> wrote:
> On Wed, Apr 2, 2008 at 10:30 AM, Simon Matter <simon.matter at invoca.ch> wrote:
>  > > Before this patch, cyrus was already able to detect a configuration
>  >  > file change,
>  >  > but only at the end of a connection. And any process waiting for a
>  >  > new connection was ignoring the change during the next connection,
>  >  > until they have finished.
>  >  > In other word, after a configuration change, any waiting process can
>  >  > still serve a new
>  >  > connection with the old configuration and let the administrator
>  >  > believe its change is not
>  >  > working.
>  >  >
>  >  > My patch force cyrmaster to send a SIGHUP to all its children when it
>  >  > detect a configuration change:
>  >  > - any working process will ignore the SIGHUP when processing a
>  >  > connection (what my patch does)
>  >  > and at the end of the connection, it will detect the configuration
>  >  > change and terminate
>  >  > (this is what is doing the original code).
>  >  > - any waiting process, will catch the SIGHUP and handle it like SIGALARM
>  >  > (what my patch does) and make the process believe its waiting period
>  >  > (-T option of imapd command) is expired and then terminate. (like was
>  >  > doing the original code)
>  >
>  >  Hi Alain,
>  >
>  >  Thanks for the patch, I'll try it out and may include it in my rpms later.
>  >  If I understand this correctly one drawback could be that on a heavy
>  >  loaded server sending SIGHUP will resuilt in much more newly created
>  >  processes after the SIGHUP has been sent. Could that be a problem somehow?
>
>
> The only difference, is that without the patch,
>  any waiting process can still serve one connection before to terminate
>  and this during the timeout
>  period of 60sec (the cyrus default)
>  Then, it should not impact the load, this should not be measurable.
>
>  Some more details, because your question was a little unclear :
>
>  - After having made change, you have to SIGHUP cyrmaster only, like
>  before! Not all imapd, pop3, ... processes.
>  - When an inactive imapd nor pop3d, ... process get the SIGHUP, it
>  will terminate immediately. Their
>  is no reasons to terminate an active process. Active process, will
>  detect the configuartion change by temself
>  at the end of the connection and terminate.
>  - cyrmaster will start a new process when new connections arrive or to
>  match "prefork" in cyrus.conf.
>
>  Regards
>
>
>
>  >
>  >  Simon
>  >
>  >
>  >
>  >  >
>  >  > Here is the patch and also in attachment.
>  >  >
>  >  > Regards
>  >  >
>  >  > --- cyrus-imapd-2.3.11/imap/signals.c.orig      2006-11-30
>  >  > 18:11:20.000000000 +0100
>  >  > +++ cyrus-imapd-2.3.11/imap/signals.c   2008-03-23 17:24:54.000000000
>  >  > +0100
>  >  > @@ -79,6 +79,12 @@
>  >  >         fatal("unable to install signal handler for %d: %m", SIGALRM);
>  >  >      }
>  >  >
>  >  > +    /* ASX: SIGHUP is used to force a configuration reload, and the
>  >  > waiting
>  >  > +     * period is a privileged moment, so we don't set SA_RESTART */
>  >  > +    if (alarm && sigaction(SIGHUP, &action, NULL) < 0) {
>  >  > +       fatal("unable to install signal handler for %d: %m", SIGHUP);
>  >  > +    }
>  >  > +
>  >  >  #ifdef SA_RESTART
>  >  >      action.sa_flags |= SA_RESTART;
>  >  >  #endif
>  >  > --- cyrus-imapd-2.3.11/master/master.c.orig     2007-10-10
>  >  > 15:59:48.000000000 +0200
>  >  > +++ cyrus-imapd-2.3.11/master/master.c  2008-03-23 17:29:33.000000000
>  >  > +0100
>  >  > @@ -1568,6 +1568,23 @@
>  >  >                 syslog(LOG_DEBUG, "init: service %s socket %d pipe %d %d",
>  >  >                        Services[i].name, Services[i].socket,
>  >  >                        Services[i].stat[0], Services[i].stat[1]);
>  >  > +        } else if (Services[i].exec && Services[i].socket) {
>  >  > +            /* refresh the old one */
>  >  > +            syslog(LOG_DEBUG, "ASX SOMETHING TO DO service %s socket
>  >  > %d pipe %d %d %d",
>  >  > +                      Services[i].name, Services[i].socket,
>  >  > +                      Services[i].stat[0], Services[i].stat[1],
>  >  > +                       Services[i].exec ? 1:0);
>  >  > +            /* send SIGHUP to all children */
>  >  > +            for (j = 0 ; j < child_table_size ; j++ ) {
>  >  > +                c = ctable[j];
>  >  > +                while (c != NULL) {
>  >  > +                    if ((c->si == i) && (c->service_state !=
>  >  > SERVICE_STATE_DEAD)) {
>  >  > +                        syslog(LOG_DEBUG, "ASX send SIGHUP to %d",
>  >  > c->pid);
>  >  > +                        kill(c->pid, SIGHUP);
>  >  > +                    }
>  >  > +                    c = c->next;
>  >  > +                }
>  >  > +            }
>  >  >         }
>  >  >      }
>  >  >
>  >  > --- cyrus-imapd-2.3.11/master/service.c.orig    2007-09-27
>  >  > 22:10:39.000000000 +0200
>  >  > +++ cyrus-imapd-2.3.11/master/service.c 2008-03-23 17:32:46.000000000
>  >  > +0100
>  >  > @@ -460,7 +460,12 @@
>  >  >                             notify_master(STATUS_FD,
>  >  > MASTER_SERVICE_UNAVAILABLE);
>  >  >                         service_abort(EX_OSERR);
>  >  >                     }
>  >  > -               }
>  >  > +                } else {
>  >  > +                     /* fd >= 0 */
>  >  > +                     /* ASX we dont want SIGHUP to disrupt a connection
>  >  > +                      * before the end */
>  >  > +                     signals_add_handlers(0);
>  >  > +                }
>  >  >             } else {
>  >  >                 /* udp */
>  >  >                 struct sockaddr_storage from;
>  >  >
>  >  >
>  >  > --
>  >  > Alain Spineux
>  >  > aspineux gmail com
>  >  > May the sources be with you
>  >  > ----
>  >  > Cyrus Home Page: http://cyrusimap.web.cmu.edu/
>  >  > Cyrus Wiki/FAQ: http://cyrusimap.web.cmu.edu/twiki
>  >  > List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
>  >
>  >
>  >
>
>
>
>
> --
>
> Alain Spineux
>  aspineux gmail com
>  May the sources be with you
>


-- 
Alain Spineux
aspineux gmail com
May the sources be with you


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