You can be assured that it's being done that way. Certainly all modern
operating systems do Copy-On-Write on memory pages, which means that
several processes with a common set of code will share much of it. This
is not being done by Apache/fastcgi/Catalyst, but by the very operating
system itself.
Linux even has a recently added capability called KSM (kernel same-page
merging) which does this even with completely unrelated processes, based
on the bare memory contents (which is pretty much more difficult than
the original case, by the way).
Regarding your question, since lots of processes have lots of shared
memory chunks, it's difficult to "blame" some process or another for
using a memory region. You can use "top" to spot the memory usage of
processes, looking at the VIRT, RSS and SHR columns. I'd use the RSS
column, but certainly the sum of this column will be much greater than
your physical RAM in a loaded server (due to shared pages).
Regards
J.
El 11/04/11 15:07, John M. Dlugosz escribió:
Looking at the server's processes, I see three of
script/myapp_fastcgi.pl, which I suppose co-inside with the Apache
configuration option where I said to start 3 fastcgi processes to
handle this app.
WebMin tells me "size", which can't be the actual load of server RAM
needed since it doesn't add up with the total usage.
Some basics here... is Apache/fastcgi/Catalyst smart enough to load
the app and get it running to the point where it is ready to start
handling requests, and THEN fork it? The Perl runtime and all the
loaded modules can certainly be shared! Do I need more advanced
configuration or app tuning to maximize this ability?
How can I tell, through WebMin or command-line tools via ssh, how much
memory is really being used by my apps?
Thanks for any pointers!
--John
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