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Re: checkpoint process use too much memory - Mailing list pgsql-admin

From jian xu
Subject Re: checkpoint process use too much memory
Date
Msg-id MN2PR05MB683257DAD723CF8BDBB4149DA1780@MN2PR05MB6832.namprd05.prod.outlook.com
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In response to Re: checkpoint process use too much memory  (jian xu <jamesxu@outlook.com>)
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btw, I checked /proc/<PID>/smaps. it looks like postgres process took most of the memory, the output is like:
===============================================================================
564415881000-56441588f000 rw-p 00857000 08:04 17682620                  postgresql/10/3/dist/bin/postgres
Size:                 56 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Rss:                  56 kB
Pss:                  56 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:        56 kB
Referenced:           56 kB
Anonymous:            56 kB
LazyFree:              0 kB
AnonHugePages:         0 kB
ShmemPmdMapped:        0 kB
Shared_Hugetlb:        0 kB
Private_Hugetlb:       0 kB
Swap:                  0 kB
SwapPss:               0 kB
Locked:                0 kB
VmFlags: rd wr mr mw me dw ac sd
5644162cf000-565d4c645000 rw-p 00000000 00:00 0                          [heap]
Size:           105745880 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Rss:            105745692 kB
Pss:            105745692 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:  105745692 kB
Referenced:     104768404 kB
Anonymous:      105745692 kB
LazyFree:              0 kB
AnonHugePages:         0 kB
ShmemPmdMapped:        0 kB
Shared_Hugetlb:        0 kB
Private_Hugetlb:       0 kB
Swap:                  0 kB
SwapPss:               0 kB
Locked:                0 kB
VmFlags: rd wr mr mw me ac sd
===============================================================================
however, the shared_buffers size is only 4GB..
postgres=# show shared_buffers ;
 shared_buffers
----------------
 4GB

thanks,

James
From: jian xu <jamesxu@outlook.com>
Sent: Tuesday, July 21, 2020 9:20
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: MichaelDBA <MichaelDBA@sqlexec.com>; Scott Ribe <scott_ribe@elevated-dev.com>; Laurenz Albe <laurenz.albe@cybertec.at>; pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: checkpoint process use too much memory
 
Thanks Tom and Alvaro. I will upgrade it to 10.13 first. 
James

From: Tom Lane <tgl@sss.pgh.pa.us>
Sent: Monday, July 20, 2020 18:34
To: jian xu <jamesxu@outlook.com>
Cc: MichaelDBA <MichaelDBA@sqlexec.com>; Scott Ribe <scott_ribe@elevated-dev.com>; Laurenz Albe <laurenz.albe@cybertec.at>; pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: checkpoint process use too much memory
 
jian xu <jamesxu@outlook.com> writes:
>       we are seeing this issue again, the checkpoint process is eating up all the memory,
> based on the htop, the checkpointer process has
> VIRT: 103G
> RES: 103G
> SHR: 4099M

hmmm ...

> my pg version is 10.3 ,

Really the *first* thing you ought to do is update to current (10.13)
and see if the problem is still there.  But if it is, maybe collecting
a memory context map in that process would be informative:

https://wiki.postgresql.org/wiki/Developer_FAQ#Examining_backend_memory_use

Note you may need a debug build for that recipe to work.

                        regards, tom lane

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