On Wed, May 25, 2022 at 12:25:28AM +0800, 徐志宇徐 wrote:
> Hi All
>
> I am a Database DBA. I focus on PostgreSQL and DB2.
> Recently. I experience some memory issue. The postgres unable allocate
> memory. I don't know how to monitor Postgres memory usage.
Postgres is just an OS Process, so should be monitored like any other.
What OS are you using ?
Know that the OS may attribute "shared buffers" to different processes, or
multiple processes.
> This server have 16G memory. On that time. The free command display only 3
> G memory used. The share_buffers almost 6G.
>
> On that time. The server have 100 active applications.
> New connection failed. I have to kill some application by os command "kill -9"
It's almost always a bad idea to kill postgres with kill -9.
> The checkpoint command execute very slow. almost need 5-10 seconds.
Do you mean an interactive checkpoint command ?
Or logs from log_checkpoint ?
> Is there any useful command to summary PostgreSQL memory usage ?
You can check memory use of an individual query with "explain (analyze,buffers) .."
https://wiki.postgresql.org/wiki/Slow_Query_Questions
What settings have you used in postgres ?
https://wiki.postgresql.org/wiki/Server_Configuration
What postgres version ?
How was it installed ? From souce? From a package ?
--
Justin
