Name of main process differs between servers (postmaster vs postgres)
Hi,
I noticed on two of my postgres servers, one has "postmaster" for the main
process, and the other has "postgres". My question is - why is this? For
example:
Server1:
postgres 909 1 0 May08 ? 00:03:55
/usr/pgsql-9.6/bin/postmaster -D /var/lib/pgsql/9.6/data/
Server2:
postgres 4804 1 0 May01 ? 00:05:08 /usr/pgsql-9.6/bin/postgres
-D /var/lib/pgsql/9.6/data
Both servers are running CentOS Linux release 7.4.1708 for the OS
and PostgreSQL 9.6.8 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5
20150623 (Red Hat 4.8.5-16), 64-bit.
The only differences I've been able to find so far are:
1) When doing a ps, server1 shows a trailing slash for the $PGDATA
directory whereas server2 doesn't have the trailing slash. I echoed $PGDATA
on both servers and they're both the same (no trailing slash).
2) Server2 has an additional package installed
-- postgresql96-contrib-9.6.8-1PGDG.rhel7.x86_64. Aside from that, both
servers have the same packages installed:
postgresql96-9.6.8-1PGDG.rhel7.x86_64
postgresql96-server-9.6.8-1PGDG.rhel7.x86_64
postgresql96-libs-9.6.8-1PGDG.rhel7.x86_64
postgresql96-pglogical-2.2.0-1.el7.x86_64
Looking at the documentation, it seems that postmaster is a deprecated
alias for the postgres process so while they differ in name, they're the
same in spirit?
From what I can tell, things are running fine on both servers, I guess I
just don't like there is a difference/inconsistency. Can anyone please
explain this?
Thanks!
Jon
On Tue, Jun 26, 2018 at 04:51:32PM -0500, Jonathan Lemig wrote:
Hi,
I noticed on two of my postgres servers, one has "postmaster" for the main
process, and the other has "postgres". My question is - why is this? For
example:
On my centos6 servers:
151814 0 lrwxrwxrwx 1 root root 8 May 10 21:32 /usr/pgsql-10/bin/postmaster -> postgres
Do you have something else ?
Is there a symlink for pg_ctl or postmaster or postgres in /s?bin, /usr/s?bin,
or /usr/local/s?bin ?
Was one started by initscript and one started by something else (manually
running pg_ctl or similar) ?
Are the initscripts the same?
Did one of them start at boot and one restarted since then ?
You might get a hint by comparing /proc/909/environ with /proc/4804/environ
(the relative pids suggests that 4804 was perhaps re/started significantly
after boot). And or proc/pid/comm, exe and stat.
Did one of them crash since it was started (or killed by OOM) ?
Justin
PS, I think the list residents would for the future to ask to keep admin/DBA
oriented questions on pgsql-general, and development/bugs on -hackers.
On Tue, Jun 26, 2018 at 2:51 PM, Jonathan Lemig <jtlemig@gmail.com> wrote:
From what I can tell, things are running fine on both servers, I guess I
just don't like there is a difference/inconsistency. Can anyone please
explain this?
Best guess, one of the servers has upgrades from previous versions applied
to it while the other started with a newer release. The upgraded server
didn't mess with a pre-existing launch script that was using postmaster
while the new one made use of the likely newer script that calls postgres.
Dave
Best guess, one of the servers has upgrades from previous versions
applied to it while the other started with a newer release. The upgraded
server didn't mess with a pre-existing launch script that was using
postmaster while the new one made use of the likely newer script that calls
postgres.
I bet it does have something to do with that. I had to migrate one of our
Postgres server from Fedora Core 24/Postgres 9.5 to CentOS 7/Postgres 9.6.
I'm new to Postgres and was playing around with different methods and
settled on using pglogical. I refined (that's being generous) the
migration process and migrated DEV and then PROD. Perhaps I should have had
our SA re-do the VMs after the refinements, but before doing the final
migrations, to make sure everything was apples-to-apples.
Thanks!
Jon
On Tue, Jun 26, 2018 at 5:04 PM, David G. Johnston <
david.g.johnston@gmail.com> wrote:
Show quoted text
On Tue, Jun 26, 2018 at 2:51 PM, Jonathan Lemig <jtlemig@gmail.com> wrote:
From what I can tell, things are running fine on both servers, I guess I
just don't like there is a difference/inconsistency. Can anyone please
explain this?Best guess, one of the servers has upgrades from previous versions
applied to it while the other started with a newer release. The upgraded
server didn't mess with a pre-existing launch script that was using
postmaster while the new one made use of the likely newer script that calls
postgres.Dave