http://bugzilla.gnome.org/show_bug.cgi?id=167714
Regards,
Martin
Am 20.02.2005 18:50:00 schrieb(en) Martin Schulze:
Hi!
This behaviour is indeed not what I would expect. slot_base::empty() is an inline function that simply checks up to two pointers for 0:
inline bool empty() const { return (!rep_ || !rep_->call_); }
So, if your app spends half of its time in slot_base::empty() it must
be called millions of times!
From what you write below, the calls to slot_base::empty() seem to
come
from signal_impl::sweep() which gets executed when slots are (auto-)
disconnected or destroyed during signal emission. signal_impl::sweep ()
iterates through the signal's slotlist to remove slots that have been
disconnected (so it's O(N)).
My only explanation for the experienced behaviour is that you have a
signal with _lots_ of slots connected and that you repeatedly emit the
signal and connect/disconnect slots during signal emission. Without further information about your code, however, it's hard to give some advice how to improve the situation.
Maybe it's also possible to optimize signal_impl::sweep(). The
difficulty is that the signal's slot list should not be changed during
signal emission. Otherwise things either get to complicated or the performance of signal::emit() suffers.
Regards,
Martin
Am 16.02.2005 17:23:14 schrieb(en) Neal E. Coombes: > I've converted our system from using an old fashioned observer > pattern > to using signals. For the most part everything performs well, but > there > is one feature that seems to take minutes instead of seconds now. > > I compiled my app for profiling and ran it for 22 minutes repeatedly > exercising this feature. At the top of my gprof output is > slot_base::empty taking 49.3% of my applications run time (being > called > 400 million times). > > I optimized the app and repeated the above. In this version at the > top > of my gprof output is signal_impl::sweep taking 50.46% of my > application > run time (being called 30 million times). > > My question: What kinds of improper use of sigc could be causing > this > (so I might remove any such cases)? On the other hand is there > anything > I might be able to do in sigc to reduce the number of times sweep > calls > empty? or perhaps reduce the number of times sweep is called all > together? > > Any and all insights much appreciated. > > Thanks, > Neal > > _______________________________________________ > libsigc-list mailing list > libsigc-list@gnome.org > http://mail.gnome.org/mailman/listinfo/libsigc-list >
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