Re: There are many processes created and died frequently during PostgreSQl idle - Mailing list pgsql-general

the process you see may be autovacuum worker process,you can tune the log_autovacuum_min_duration to log the autovacuum activities and check if the pids match

http://www.postgresql.org/docs/9.2/static/runtime-config-autovacuum.html

2013/5/24 高健 <luckyjackgao@gmail.com>

Hello all:

I  found that  during postgresql running, there are so many processes being created and then died.

I am interested in the reason.

Here is the detail:

I installed from postgresql-9.2.1.tar.bz2.

I put some debug code in fd.c 's PathNameOpenFile function:

fprintf(stderr,"+++While Calling PathNameOpenFile pid=%d.....",getpid();

fprintf(stderr,"VfdCache Address is: %p \n\n",VfdCache);

When it run, I open two termianal using psql(pid=22109 and pid=22114), then I can got information like this:

[postgres@lex pgsql]$ ./bin/pg_ctl -D ./data start

server starting

[postgres@lex pgsql]$ LOG:  database system was shut down at 2013-05-24 09:28:59 CST

LOG:  autovacuum launcher started

+++While Calling PathNameOpenFile pid=22106.....VfdCache Address is: 0xbfb3320 

LOG:  database system is ready to accept connections

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22109.....VfdCache Address is: 0xbfb2de0 

+++While Calling PathNameOpenFile pid=22114.....VfdCache Address is: 0xbfba400 

+++While Calling PathNameOpenFile pid=22114.....VfdCache Address is: 0xbfba400 

+++While Calling PathNameOpenFile pid=22114.....VfdCache Address is: 0xbfba400 

+++While Calling PathNameOpenFile pid=22114.....VfdCache Address is: 0xbfba400 

+++While Calling PathNameOpenFile pid=22120.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22120.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22120.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22127.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22127.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22127.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22134.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22134.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22134.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22142.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22142.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22142.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22149.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22149.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22149.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22156.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22156.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22156.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22165.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22165.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22165.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22171.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22171.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22171.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22178.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22178.....VfdCache Address is: 0xbfe6700 

+++While Calling PathNameOpenFile pid=22178.....VfdCache Address is: 0xbfe6700 

But when I grep process information using ps command, I can't find process such like 22120,22127,22134,22142,22149,22156,22178.

And the output is growing longer and longer...

[root@lex ~]# ps -ef | grep post

root      4641  4621  0 08:28 pts/3    00:00:00 su - postgres

postgres  4642  4641  0 08:28 pts/3    00:00:00 -bash

root      4709  4688  0 08:28 pts/4    00:00:00 su - postgres

postgres  4710  4709  0 08:28 pts/4    00:00:00 -bash

root      4772  4751  0 08:29 pts/5    00:00:00 su - postgres

postgres  4773  4772  0 08:29 pts/5    00:00:00 -bash

postgres 22101     1  0 09:45 pts/3    00:00:00 /usr/local/pgsql/bin/postgres -D ./data

postgres 22103 22101  0 09:45 ?        00:00:00 postgres: checkpointer process         

postgres 22104 22101  0 09:45 ?        00:00:00 postgres: writer process               

postgres 22105 22101  0 09:45 ?        00:00:00 postgres: wal writer process           

postgres 22106 22101  0 09:45 ?        00:00:00 postgres: autovacuum launcher process   

postgres 22107 22101  0 09:45 ?        00:00:00 postgres: stats collector process      

postgres 22108  4710  0 09:45 pts/4    00:00:00 ./psql

postgres 22109 22101  0 09:45 ?        00:00:00 postgres: postgres postgres [local] idle

postgres 22113  4773  0 09:46 pts/5    00:00:00 ./psql

postgres 22114 22101  0 09:46 ?        00:00:00 postgres: postgres postgres [local] idle

root     22187  6429  0 09:55 pts/6    00:00:00 grep post

[root@lex ~]# 

So I think that some process is created and then quickly died . But would somebody can kindly say what are the purpose of those process?

How about using one worker process and keep it be alive?

--
Jov

blog: http:amutu.com/blog