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Re: Question about Pattern.matcher performance differences between Java6 and Java7/8

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On 12/24/2013 7:26 AM, zach.lists@gmail.com wrote:
> Hello,
>
> I've noticed a difference in performance between Java6 and Java7/8 (Oracle) on OS X with some toy code. Java6 runs much faster than the updated versions.
>
> VisualVM is pointing me to java.util.regex.Pattern.matcher being the hotspot where all the time is now spent.
>
> I'm still trying to slim down the offending code into a concise example. However I was wondering if anyone knew if there were any changes in java.util.regex.Pattern.matcher performance between Java6 and Java7?
>
> I've read that named groups were introduced in Java7, but I haven't found anything mentioning performance tanking dramatically.
>
> Thanks for any leads you folks may be able to point me to.

     One suggestion: Don't fret about the performance of "toy code."

     If the performance of "real code" suffers, that's another matter.
Note, though, that if Pattern.matcher() has suddenly become the hot
spot in real code it doesn't necessarily follow that Pattern.matcher()
has become slower.  It might instead mean that something else is now
matching a lot more regexes than it used to, or is using a more
complex regex than before.  If your car's fuel economy suddenly gets
worse it doesn't prove the engine's gone bad, it may instead have
something to do with the boat trailer you've hitched on ...

-- 
Eric Sosman
esosman@comcast-dot-net.invalid

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Question about Pattern.matcher performance differences between Java6 and Java7/8 zach.lists@gmail.com - 2013-12-24 04:26 -0800
  Re: Question about Pattern.matcher performance differences between Java6 and Java7/8 Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-12-24 09:31 -0500
    Re: Question about Pattern.matcher performance differences between Java6 and Java7/8 Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2013-12-25 11:47 -0800
      Re: Question about Pattern.matcher performance differences between Java6 and Java7/8 Robert Klemme <shortcutter@googlemail.com> - 2013-12-26 13:51 +0100
      Re: Question about Pattern.matcher performance differences between Java6 and Java7/8 Eric Sosman <esosman@comcast-dot-net.invalid> - 2013-12-26 08:51 -0500
      Re: Question about Pattern.matcher performance differences between Java6 and Java7/8 Arved Sandstrom <asandstrom2@eastlink.ca> - 2013-12-26 13:25 -0400

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