Hi,
As I said, it just isn't that simple when shared memory is involved. A
rough measure for PostgreSQL is the virtual size of one of the
processes, plus the working sets of all the others. Alternately, you can
reasonably estimate the memory consumption by adding all the working
sets and then adding the value of shared_buffers to that - this will
under-estimate usage slightly because PostgreSQL also uses shared memory
for other things, but not tons of it in a normal configuration.
This is interesting. About the virtual size of one of the process,
which process I should look up? Is the one who has the biggest virtual
size?
http://i45.tinypic.com/vr4t3b.png
For example, from the above screenshot, the biggest virtual size from
all postgresql process is 740004. So can we said the total approximate
of memory usage of the postgresql service is 740004 K +
total_of_working_sets (4844 K + 10056 K + 5408 K + 6020 K + ...) ?
Sure, that's what you see, but you should really be looking at the
numbers. Swap in and out bytes, memory usage, etc. In Windows 7 or
Win2k8 Server you'd use the Performance Monitor for that; I don't
remember off the top of my head where to look in XP.
I had total paging file size = 3GB.
There is perfmon.exe in windows xp, but don't know how to use and
analyze the graph.
I'd say your problem has nothing to do with PostgreSQL.
Maybe you're right. If I close one of the memory porks, it gets a bit
better. Maybe I was too quick to blame postgreSQL, it's just that I
can't close and restart other applications because they are either too
important or slow to reload, where postgresql service is very quick in
restarting. I hope it'll understand.
On Wed, Nov 14, 2012 at 6:07 AM, Craig Ringer cr...@2ndquadrant.com wrote:
Please reply to the list, not directly to me. Comments follow in-line.
On 11/13/2012 11:37 PM, Wu Ming wrote:
Hi,
What column in Process Explorer to determine memory usage? Currently I
thought Working Set is the correct one.
As I said, it just isn't that simple when shared memory is involved. A
rough measure for PostgreSQL is the virtual size of one of the
processes, plus the working sets of all the others. Alternately, you can
reasonably estimate the memory consumption by adding all the working
sets and then adding the value of shared_buffers to that - this will
under-estimate usage slightly because PostgreSQL also uses shared memory
for other things, but not tons of it in a normal configuration.
The 'lagging' is like when you try to alt+tab or activating/focusing
other application window, or changing tab in browser, it goes slow or
lagged in its UI loading.
Sure, that's what you see, but you should really be looking at the
numbers. Swap in and out bytes, memory usage, etc. In Windows 7 or
Win2k8 Server you'd use the Performance Monitor for that; I don't
remember off the top of my head where to look in XP.
My firefox has many tabs opened (around 30 tabs) and eclipse is well
known as its high memory usage.
On a 2GB machine? Yup, that'll do it.
You've shown a screenshot that suggests that Pg is using relatively
little RAM, and you're running two known memory pigs. I'd say your
problem has nothing to do with PostgreSQL.
Then usually I also opened opera and
chrome with ~10-20 tabs opened.
Time to buy more RAM.
I saw that chrome also spawned many
process (I had 4 tabs opened, but it shows 8 child process). They
might be the big process that probably is the main cause of the
lagging.
It's going to be everything adding up. Chrome, Eclipse, Firefox, all
fighting for RAM.
BTW, chrome uses a multi-process architecture like PostgreSQL, but
unlike PostgreSQL it does not use shared memory, so you can tell how
much RAM Chrome is using very easily by adding up the working sets.
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training Services
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