Hi all,
I was curious what the latest pan looked like so I pulled down debian
unstable (0.139-1). There was a remarkable slowdown and much higher CPU
usage when pulling binaries from large groups as compared to 0.133.
I grabbed the latest git code and did a little profiling. Eventually I
found a curious call being made in pan/gui/header-pane.cc, line 2527:
void
HeaderPane :: on_cache_added (const Quark& message_id)
{
quarks_t q;
q.insert(message_id);
_data.rescore_articles ( _group, q ); // here is slow
rebuild_article_action (message_id);
}
That rescore_articles call eventually gets down to a std::set_intersection
over what I believe to be the entire list of articles in the group of
interest.
This on_cache_added call is made fairly often, possibly each time an
article's contents are retrieved.
I couldn't see anything terribly valuable in this call since I don't use
scoring other than to plonk authors so I commented out the three related
lines and saw my bandwidth get fully utilized again.
As for treating this, the code is doing an intersection with a single
element set (the one quark), which is effectively a find. There might be a
faster find if these articles are already hashed. I don't know enough
about the system to suggest a complete new codepath. There might be a
"user doesn't use scoring" flag that flat avoids this call.
Eric Ortega
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