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Re: [HACKERS] autovacuum does not start in HEAD

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>
Cc: pgsql-patches(at)postgresql(dot)org, alvherre(at)commandprompt(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] autovacuum does not start in HEAD
Date: 2007-04-27 02:57:37
Message-ID: 200704270257.l3R2vbh13624@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Your patch has been added to the PostgreSQL unapplied patches list at:

	http://momjian.postgresql.org/cgi-bin/pgpatches

It will be applied as soon as one of the PostgreSQL committers reviews
and approves it.

---------------------------------------------------------------------------


ITAGAKI Takahiro wrote:
> I wrote:
> > I found that autovacuum launcher does not launch any workers in HEAD.
> 
> The attached autovacuum-fix.patch could fix the problem. I changed
> to use 'greater or equal' instead of 'greater' at the decision of
> next autovacuum target.
> 
> The point was in the resolution of timer; There is a platform that timer
> has only a resolution of milliseconds. We initialize adl_next_worker with
> current_time in rebuild_database_list(), but we could use again the same
> value in do_start_worker(), because there is no measurable difference
> in those low-resolution-platforms.
> 
> 
> Another attached patch, autovacuum-debug.patch, is just for printf-debug.
> I got the following logs without fix -- autovacuum never works.
> 
> # SELECT oid, datname FROM pg_database ORDER BY oid;
>   oid  |  datname  
> -------+-----------
>      1 | template1
>  11494 | template0
>  11495 | postgres
>  16384 | bench
> (4 rows)
> 
> # pgbench bench -s1 -c1 -t100000
> [with configurations of autovacuum_naptime = 10s and log_min_messages = debug1]
> 
> LOG:  do_start_worker skip : 230863399.250000, 230863399.250000, 230863409.250000
> LOG:  rebuild_database_list: db=11495, time=230863404.250000
> LOG:  rebuild_database_list: db=16384, time=230863409.250000
> DEBUG:  autovacuum: processing database "bench"
> LOG:  do_start_worker skip : 230863404.250000, 230863404.250000, 230863414.250000
> LOG:  do_start_worker skip : 230863404.250000, 230863409.250000, 230863414.250000
> LOG:  rebuild_database_list: db=11495, time=230863409.250000
> LOG:  rebuild_database_list: db=16384, time=230863414.250000
> LOG:  do_start_worker skip : 230863409.250000, 230863409.250000, 230863419.250000
> LOG:  do_start_worker skip : 230863409.250000, 230863414.250000, 230863419.250000
> LOG:  rebuild_database_list: db=11495, time=230863414.250000
> LOG:  rebuild_database_list: db=16384, time=230863419.250000
> ...
> (no autovacuum activities forever)
> 
> Regards,
> ---
> ITAGAKI Takahiro
> NTT Open Source Software Center
> 

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-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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