Re: pg14b1 stuck in lazy_scan_prune/heap_page_prune of pg_statistic

On Tue, Jun 08, 2021 at 02:01:51PM -0400, Alvaro Herrera wrote:
> On 2021-Jun-08, Justin Pryzby wrote:
> 
> > On Tue, Jun 08, 2021 at 12:06:02PM -0400, Alvaro Herrera wrote:
> > > On 2021-Jun-06, Justin Pryzby wrote:
> > > 
> > > > However, I also found an autovacuum chewing 100% CPU, and it appears the
> > > > problem is actually because autovacuum has locked a page of pg-statistic, and
> > > > every other process then gets stuck waiting in the planner.  I checked a few
> > > > and found these:
> > > 
> > > Hmm ... I wonder if this could be related to commits d9d076222f5b,
> > > c98763bf51bf, etc.  I don't have any connecting thoughts other than the
> > > tuple visibility code being involved.  Do you see any procs with the
> > > PROC_IN_SAFE_IC flag set?
> > 
> > Can you give me a hint how to do that from a corefile ?
> 
> (gdb) set $i=0
> (gdb) set $total = ProcGlobal->allProcCount
> (gdb) while($i<$total)
>  >print ProcGlobal->allProcs[$i++]->statusFlags
>  >end

They're all zero except for:

$201 = 1 '\001'
$202 = 3 '\003'
$203 = 1 '\001'

src/include/storage/proc.h-#define              PROC_IS_AUTOVACUUM      0x01    /* is it an autovac worker? */
src/include/storage/proc.h-#define              PROC_IN_VACUUM          0x02    /* currently running lazy vacuum */
src/include/storage/proc.h:#define              PROC_IN_SAFE_IC         0x04    /* currently running CREATE INDEX

-- 
Justin