Thread: 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.
Re: Name of main process differs between servers (postmaster vs postgres)
From
"David G. Johnston"
Date:
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:
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