[Libreoffice] Trying to diagnose base running extremely slowly

[Stephan Bergmann]

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