Re: An example of bugs for Hot Standby

On Thu, 2010-01-21 at 18:01 +0900, Hiroyuki Yamada wrote:
> >Deadlock bug was prevented by stop-gap measure in December commit.
> >
> >Full resolution patch attached for Startup process waits on buffer pins.
> >
> >Startup process sets SIGALRM when waiting on a buffer pin. If woken by
> >alarm we send SIGUSR1 to all backends requesting that they check to see
> >if they are blocking Startup process. If so, they throw ERROR/FATAL as
> >for other conflict resolutions. Deadlock stop gap removed.
> >max_standby_delay = -1 option removed to prevent deadlock.
> >
> >Reviews welcome, otherwise commit at end of week.
> >
>
> I think the patch has two problems.
>
> * disable_standby_sig_alarm() does not clear standby_timeout_active flag
> when it succeeds in disabling the alarm.
>
> * Assertion check in HoldingBufferPinThatDelaysRecovery() can fail
> with following scenario.

Updated patch, including changes from Andres and Hiroyuki.

--
Simon Riggs www.2ndQuadrant.com