Re: bg writer went away after reload

[Matthew Chambers <mchambers@xxxxxxxxxxxx>]

This is postgres 9.3.2.

This is what the log shows.

Mar 11 08:16:29 jupiter521 postgres[2026]: [8-1] 2014-03-11 08:16:29 NZDTLOG:  received SIGHUP, reloading configuration files
Mar 11 08:16:29 jupiter521 postgres[2026]: [9-1] 2014-03-11 08:16:29 NZDTLOG:  parameter "bgwriter_lru_maxpages" changed to "200"

Here are the processes I have running besides the connections. 

postgres  2028  0.0  8.3 17245532 8279356 ?    Ss   Mar09   2:42 postgres: checkpointer process                                
postgres  2029  0.0  0.1 17245272 107900 ?     Ss   Mar09   0:08 postgres: writer process                                      
postgres  2030  0.2  0.0 17245272 34248 ?      Ss   Mar09   6:44 postgres: wal writer process                                  
postgres  2031  0.0  0.0 17246164 2596 ?       Ss   Mar09   0:09 postgres: autovacuum launcher process                         
postgres  2032  0.0  0.0  18152  1244 ?        Ss   Mar09   0:06 postgres: archiver process   last was 0000000100000202000000F8
postgres  2033  0.0  0.0  18568  1636 ?        Ss   Mar09   1:47 postgres: stats collector process
postgres  3914  0.4  0.0 17246520 2844 ?       Ss   Mar09  14:04 postgres: wal sender process postgres 192.168.122.54(48686) streaming 202/F996C000

Is it the "writer process"?  I was sure it was called the background writer before.

-Matt

On 11/03/14 12:03, Venkata Balaji Nagothi wrote:

On Tue, Mar 11, 2014 at 8:30 AM, Matthew Chambers <mchambers@xxxxxxxxxxxx> wrote:

Hi, just wondering if this is normal, DB is operating just fine.

I upped bgwriter_lru_maxpages to 200 and issued a reload.  Normally, I'd see the bgwriter constantly churning as one of my main I/O using processes, but now I have:

postgres: wal writer process
postgres: checkpointer process

The wal writer seems to have taken over.  Does this make sense?

What WAL writer does is completely different from the way bgwriter functions. These two critical background processes of PostgreSQL performing independent I/O operations independently.One cannot take over another.

which version of Postgres is this ?

Do you see anything in the Postgres logs ? Do you see any message which indicates that reloading of the new configuration in postgresql.conf file was successful ?

Venkata Balaji N

Sr. Database Administrator

Fujitsu Australia