Bugs item #19772, was opened at 2008-04-25 08:40
You can respond by visiting:
http://rubyforge.org/tracker/?func=detail&atid=1971&aid=19772&group_id=494
Category: None
Group: None
>Status: Closed
>Resolution: Rejected
Priority: 3
Submitted By: Nobody (None)
>Assigned to: Charlie Savage (cfis)
Summary: Node#== incredibly slow!
Initial Comment:
When I replaced my REXML implementation of a time-critic routine with a Libxml
implementation, the Libxml version took more than THREE TIMES LONGER than the
REXML version! To investigate the reason, I reduced the implementation
differences to a few core indivisibles and then ran ruby-prof, and discovered
that Libxml was wasting huge amounts of time in Node#==
86.97% 0.46% 7.54 0.04 0.00 7.50 962
Opmllibxml#goleftone
7.49 7.48 0.00 0.01
962/962 XML::Node#==
0.01 0.01 0.00 0.00
962/962 XML::Node#parent
My code says:
def goleftone()
parent = @curline.parent
if parent == @top
return false
else
@curline = parent
return true
end
end
(In other words, I already have a node called @top, of which @curline points to
an element at some depth; I repoint @curline to point at its own parent, unless
its own parent *is* @top.)
I replaced my test, parent == @top, by a different test, using parent.name, and
my routine went from 10.3 seconds to 2.2 seconds. Rather significant (though
still not really very much faster than REXML).
Unfortunately, this change caused me to get repeated error messages of the
following form:
ruby(1350) malloc: *** error for object 0x12cd520: incorrect checksum for freed
object - object was probably modified after being freed, break at szone_error
to debug
ruby(1350) malloc: *** set a breakpoint in szone_error to debug
However, I believe that this latter is something you may already know about.
----------------------------------------------------------------------
>Comment By: Charlie Savage (cfis)
Date: 2008-07-07 01:08
Message:
This is because libxml-ruby defines == to mean that two nodes have the same xml
representation. What you are after is Ruby's equal? method, not the eql?
method (which == uses).
----------------------------------------------------------------------
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