HP-UX performance problem

[Gordon Guthrie <gdg@soco.agilent.com>]

I've discovered a performance problem with openldap 2.2.20 running on
HP-UX 11i.

If logging level is turned up high enough, 
bdb(o=xyzzy.com): unable to lock mutex: Invalid argument
shows occasionally in the log during a search for 2900 entries.  This
search takes ~ 1.5 sec.

However if I make the same search simultaneously from 2 different
machines, I get > 100000 "unable to lock mutex: Invalid argument" 
messages and the elapsed time goes to > 55 sec.

I discovered that removing PHKL_25367 restores the performance.  The 
mutex entries disappear, and the search takes 1.2 sec for a the
single query and 1.9 sec for the double.

PHKL_25367 has been supeseeded by PHKL_30837 which has worse performance
The single search takes 17 sec with > 5800 mutex entries while the 
double search takes >> 23 min with > 27000 mutex entries.  
(I abandonded the double search after 23 min).


These experiments were performed on openldap 2.2.20 which used 
Berkley DB 4.2.52, but I've seen the same symptoms with  
openldap 2.2.23 using Berkley DB 4.3.27.

Any idea what is going on?  

Thanks,

Gordon Guthrie