Improve performance of backtrace filtering
Reported by James Mead | March 17th, 2010 @ 07:11 PM
Nikolai Weibull posted the following to the Mocha mailing list :-
Mocha::BacktraceFilter creates a new
Regexp object for every line of every backtrace it
filters. It also calls File.expand_path for each such
line.
The Regexp object creation can easily be removed by
creating it once in #initialize.
File.expand_path might be more difficult to get rid
of, but File.expand_path is slow, at least on Windows.
Getting rid of all those calls to it would thus save a lot of time.
Rewriting BacktraceFilter to that below makes running
my 108 tests with Expectations run in less than a third of the
time:
def initialize(lib_directory = LIB_DIRECTORY)
@lib_directory = Regexp.new('^' + Regexp.escape(lib_directory))
end
def filtered(backtrace)
backtrace.reject { |location| @lib_directory.match(location) }
end
I realize that this doesn’t filter backtraces correctly if
Mocha’s paths are relative. I was, however, hoping that
someone with more knowledge in this area would be able to resolve
this. Perhaps setting LIB_DIRECTORY =
File.dirname(File.dirname(__FILE__)) + File::SEPARATOR is a
good way of doing it? Then both @lib_directory and
location will both be relative or absolute, depending
on how Mocha was required.
Comments and changes to this ticket
-
-
James Mead November 26th, 2010 @ 11:41 AM
- State changed from “new” to “open”
@nikolai: Apologies for the (very) slow response. I've just been looking at this and thinking about it a bit. I've made the change so that the
Regexpinstance is now only created once in theBacktraceFilter#initializemethod.However, I've also realized that (a) this probably won't improve performance because a new
BacktraceFilterinstance is created for every expectation error; and (b) in any case, any performance improvement will only be apparent for people who have a lot of test failing with expectation errors. This latter case seems like a bit of an edge case, so I'm not going to make the other changes.I'm closing this ticket. Thanks, James.
-
James Mead November 26th, 2010 @ 11:41 AM
- State changed from “open” to “resolved”
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A mocking & stubbing library for Ruby.
* <a href="http://github.com/floehopper/mocha">GitHub repository</a>
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James Mead