Thanks for Jov's reply.
I traced it again, and found they are really for autovacuum.
I found that
some will call proc_exit() from within AutoVacLauncherMain function,
some will call proc_exit() from within AutoVacWorkerMain function.
But I wonder why not using only a few daemon , instead of making those processes be short life.
2013/5/24 Jov <amutu@xxxxxxxxx>
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--2013/5/24 高健 <luckyjackgao@xxxxxxxxx>
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 startserver starting[postgres@lex pgsql]$ LOG: database system was shut down at 2013-05-24 09:28:59 CSTLOG: autovacuum launcher started+++While Calling PathNameOpenFile pid=22106.....VfdCache Address is: 0xbfb3320LOG: 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: 0xbfe6700But 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 postroot 4641 4621 0 08:28 pts/3 00:00:00 su - postgrespostgres 4642 4641 0 08:28 pts/3 00:00:00 -bashroot 4709 4688 0 08:28 pts/4 00:00:00 su - postgrespostgres 4710 4709 0 08:28 pts/4 00:00:00 -bashroot 4772 4751 0 08:29 pts/5 00:00:00 su - postgrespostgres 4773 4772 0 08:29 pts/5 00:00:00 -bashpostgres 22101 1 0 09:45 pts/3 00:00:00 /usr/local/pgsql/bin/postgres -D ./datapostgres 22103 22101 0 09:45 ? 00:00:00 postgres: checkpointer processpostgres 22104 22101 0 09:45 ? 00:00:00 postgres: writer processpostgres 22105 22101 0 09:45 ? 00:00:00 postgres: wal writer processpostgres 22106 22101 0 09:45 ? 00:00:00 postgres: autovacuum launcher processpostgres 22107 22101 0 09:45 ? 00:00:00 postgres: stats collector processpostgres 22108 4710 0 09:45 pts/4 00:00:00 ./psqlpostgres 22109 22101 0 09:45 ? 00:00:00 postgres: postgres postgres [local] idlepostgres 22113 4773 0 09:46 pts/5 00:00:00 ./psqlpostgres 22114 22101 0 09:46 ? 00:00:00 postgres: postgres postgres [local] idleroot 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?
Jovblog: http:amutu.com/blog
