On 10/19/2011 05:07 PM, Michael Meeks wrote:
On Wed, 2011-10-19 at 16:34 +0200, Stephan Bergmann wrote:
(the number is not always 72) that is repeated more or less identically
some 12,000 times in the 7 minute run. Since each set appears to take
around .02 seconds that alone would account for some 4 minutes of the run.

7321 times reading out /proc/self/map -- no idea why it does that, but
that clearly ain't no good...

        Yep :-) If I remember rightly - the only moving part in this
side-to-side performance comparison that causes a substantial decrease
in performance is Java 7 vs 6 right ? The strace shows it poking
at /proc/self/map endlessly (something that is not done by any
LibreOffice code I can find off hand), which perhaps helps isolate the
problem rather better ?

What the LibO hsqldb code does a lot is call JNI's Attach/DetachCurrentThread. Googling around, <http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6929067> "Stack guard pages should be removed when thread is detached" suggests that reading /proc/self/maps might have been added into Attach/DetachCurrentThread as part of a bug fix. That would explain things.

-Stephan
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