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From "Jeff Trawick" <traw...@gmail.com>
Subject Re: Graceful restart not so graceful?
Date Wed, 07 Jan 2009 12:02:31 GMT
On Wed, Jan 7, 2009 at 6:03 AM, Joe Orton <jorton@redhat.com> wrote:

> On Tue, Jan 06, 2009 at 12:10:25PM -0600, William Rowe wrote:
> > Would folks comment on Nathan's, Joe's and Stefan's work on
> >
> > https://issues.apache.org/bugzilla/show_bug.cgi?id=42829
> >
> > and offer any comments on why this patch;
> >
> > https://issues.apache.org/bugzilla/attachment.cgi?id=22822
> >
> > should not be applied to trunk/ and branches/2.2.x/ in time for
> > the next releases?
>
> I never found the time to commit this for a bunch of reasons:
>
> 1) I never convinced myself that adding a bunch of complexity to
> prefork, per Stefan's patch, was the right way to address this
>
> 2) I never worked out what impact the lack of check on the poll
> descriptor event type (POLLERR etc) had on this, but that needs
> resolving too
>
> 3) I hadn't checked whether worker et al had similar issues
>
> 4) I think that a simpler solution to this problem would be to add a
> timeout (e.g. 30s) on the child pollset_poll() call so they are
> guaranteed to pop at some point, but I haven't had time to try this or
> work out whether that will suck in some other way.


Initial testing of your idea for a timeout was promising.  I'll try to test
it with graceful stop as well.

Index: server/mpm/prefork/prefork.c
===================================================================
--- server/mpm/prefork/prefork.c    (revision 731724)
+++ server/mpm/prefork/prefork.c    (working copy)
@@ -540,10 +540,12 @@
                 apr_int32_t numdesc;
                 const apr_pollfd_t *pdesc;

-                /* timeout == -1 == wait forever */
-                status = apr_pollset_poll(pollset, -1, &numdesc, &pdesc);
+                /* timeout == 10 seconds to avoid a hang at graceful
restart/stop
+                 * caused by the closing of sockets by the signal handler
+                 */
+                status = apr_pollset_poll(pollset, apr_time_from_sec(10),
&numdesc, &pdesc);
                 if (status != APR_SUCCESS) {
-                    if (APR_STATUS_IS_EINTR(status)) {
+                    if (APR_STATUS_IS_TIMEUP(status) ||
APR_STATUS_IS_EINTR(status)) {
                         if (one_process && shutdown_pending) {
                             return;
                         }

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