Comments on: Rails expire_fragment(regex) Considered Harmful http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/ Thu, 20 Nov 2008 22:41:00 +0000 http://wordpress.org/?v=2.3.3 By: Scott Lamb http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-19948 Scott Lamb Sat, 17 Nov 2007 02:07:36 +0000 http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-19948 glob() is better than that but still not fast - it just gets all the directory entries and does an fnmatch() on each one. On my ~1-year-old CentOS 5 Linux machine with warm cache, I just timed a non-matching glob() at 2 us per directory entry. Each unlink() also takes about 2 us. So that's an unnecessary 10 ms if you have 5,000 cache entries, or an unnecessary 200 ms if you have 100,000. Much better to just unlink() the entries that might be there than look at every entry first. glob() is better than that but still not fast - it just gets all the directory entries and does an fnmatch() on each one.

On my ~1-year-old CentOS 5 Linux machine with warm cache, I just timed a non-matching glob() at 2 us per directory entry. Each unlink() also takes about 2 us. So that’s an unnecessary 10 ms if you have 5,000 cache entries, or an unnecessary 200 ms if you have 100,000. Much better to just unlink() the entries that might be there than look at every entry first.

]]> By: Ken http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-2336 Ken Mon, 05 Mar 2007 19:34:50 +0000 http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-2336 Ruby does have a glob method in the Dir class: http://www.ruby-doc.org/core/classes/Dir.html#M002374 Couldn't you just use that to get the list of files (hopefully quickly) and then call expire_fragment on the results? Ruby does have a glob method in the Dir class:

http://www.ruby-doc.org/core/classes/Dir.html#M002374

Couldn’t you just use that to get the list of files (hopefully quickly) and then call expire_fragment on the results?

]]> By: Ken http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-2225 Ken Fri, 02 Mar 2007 20:39:47 +0000 http://gurge.com/blog/2007/02/04/rails-expire_fragmentregex-considered-harmful/#comment-2225 Any way to force it to behave like glob instead of a stupid regex? Unix solved making globbing fast about 30 years ago. Any way to force it to behave like glob instead of a stupid regex? Unix solved making globbing fast about 30 years ago.

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