Simon Riggs wrote:
On Fri, 2009-01-30 at 16:55 +0200, Heikki Linnakangas wrote:
Ok, here's an attempt to make shutdown work gracefully.
Startup process now signals postmaster three times during startup: first
when it has done all the initialization, and starts redo. At that point.
postmaster launches bgwriter, which starts to perform restartpoints when
it deems appropriate. The 2nd time signals when we've reached consistent
recovery state. As the patch stands, that's not significant, but it will
be with all the rest of the hot standby stuff. The 3rd signal is sent
when startup process has finished recovery. Postmaster used to wait for
the startup process to exit, and check the return code to determine
that, but now that we support shutdown, startup process also returns
with 0 exit code when it has been requested to terminate.
Yeh, seems much cleaner.
Slightly bizarre though cos now we're pretty much back to my originally
proposed design. C'est la vie.
Yep. I didn't see any objections to that approach in the archives. There
was other problems in the early versions of the patch, but nothing
related to this arrangement.
I like this way because it means we might in the future get Startup
process to perform post-recovery actions also.
Yeah, it does. Do you have something in mind already?
Your call to PMSIGNAL_RECOVERY_COMPLETED needs to be if
(IsUnderPostmaster), or at least a comment to explain why not or perhaps
an Assert.
Nah, StartupProcessMain is only run under postmaster; you don't want to
install signal handlers in a stand-along backend. Stand-alone backend
calls StartupXLOG directly.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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