On Wed, Mar 9, 2011 at 9:42 AM, Edmundo Robles L.
<erobles@sensacd.com.mx> wrote:
> Hi everyone!
>
> I have a doubt about the memory consumed by each connection open.
>
> suddenly my server, running postgres 8.3.11, began to run too slowly.
>
> Checking the process with: ps -adelfo pcpu,vsz,args | more
>
> The processes,related to the connection to the db, each one have a consume of memory near to the 50Mb. by the way i
have50 connections to the db, so i have a reported memory consumed of 2.5M, when i have only 1G in the server.
>
> If I modify the shared_buffers value, the report of memory consumed is according with shared buffers value.
The most likely explanation is that you're misinterpreting the restuls
of your ps output. Vsize is virtual size which includes all libs
linked whether loaded or not and the amount of shared memory the
process is touching. For instance, here's the output of top on my
machine running postgres at work:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
14037 dgish 20 0 4259m 455m 445m R 98 0.4 31:16.24 postgres
32318 dgish 20 0 4260m 2.0g 1.9g R 98 1.6 0:08.59 postgres
32464 dgish 20 0 4263m 1.4g 1.4g R 91 1.2 0:06.96 postgres
2150 dgish 20 0 4254m 227m 220m S 86 0.2 0:01.94 postgres
866 dgish 20 0 4270m 1.5g 1.4g S 50 1.2 0:08.46 postgres
29930 dgish 20 0 4263m 1.6g 1.6g R 34 1.3 0:15.99 postgres
888 dgish 20 0 4259m 239m 230m S 33 0.2 0:02.01 postgres
Note that virt is a tad over 4G. Can you guess what my shared_buffers
are set to? Yep, 4G. Each process is aware of all the
shared_buffers. Actual resident / in use memory ranges from 455M to
2G, but we subtract the shared memory it's using right now for
shared_buffers and we get a delta, which is in the 100Meg or less
range. So each individual backend is using < !00Meg (good thing I've
got several huindred of them).
