On Sat, Jun 19, 2010 at 8:46 AM, Claus Reinke <claus.rei...@talk21.com>
wrote:
I put the simple version at
http://hpaste.org/fastcgi/hpaste.fcgi/view?id=26329#a26329
This one displays much better performance with DList + Writer.Strict
than List + StrictWriter so I guess it's not too surprising. However,
*something* is still generating a lot of lag
Some lag is to be expected: logging is about creating
and recording data for later use. You'd need to annotate
Indeed, though I don't think this is the case, because I get lots of
lag even when no logs are written.
In the part you deleted I mentioned one source of lag that does
not disappear when no logs are written, and a way of using
profiling cost centers to track down other sources (the ones
I mentioned accounted for 2/3 of lag in the "profile_logging"
profile, according to "-hblag -hc -L40" on SCC-annotated
source).
My conclusion is that my contrived tests are not useful because the
whole point is to get a controlled situation by simplifying it, but
even the simple version displays mysterious behaviour.
It is sometimes difficult to produce a simplified version that
has strictly fewer problems than the full version, especially
if the simple version is not derived from the full version but
from simplifying assumptions. Nevertheless, the simpler
version has less code, and it is therefore helpful to try and
understand its behaviour before returning to full complexity.
In particular, it is important to figure out which problematic
aspects of the simple version also apply to the full version
and which problems can be ignored because they cannot
occur in the full version.
I should go back to poking at the production version. Even
if I don't understand the changes I'm making, at least when
I get a speedup I'm more sure it translates to a real speed
up in the application.
That way lies madness. Not recommended unless you are
producing code that noone is ever going to look at again,
and even then you'll be writing similar code in the future,
so it is better to put in the energy once to puzzle out
those mysterious details!-)
Claus
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