lib/41019: pthreads: high load when using varnish (locking/unlocking causes 98% WCPU)

[michael+netbsd%stapelberg.de@localhost]

>Number:         41019
>Category:       lib
>Synopsis:       pthreads: high load when using varnish (locking/unlocking 
>causes 98% WCPU)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 15 11:05:00 +0000 2009
>Originator:     Michael Stapelberg
>Release:        5.99.8
>Organization:
>Environment:
NetBSD ms 5.99.8 NetBSD 5.99.8 (GENERIC) #10: Sun Mar 15 08:56:03 CET 2009
>Description:
When using varnish 2.0.3, which makes use of pthreads, WCPU und CPU usage is 
extremely high. I guess this is a bug in lib/libpthread on NetBSD, as this 
doesn?t happen on Linux or FreeBSD.
>How-To-Repeat:
Start varnish using the following command (warning: www/varnish in pkgsrc is 
extremely old, download/compile 2.0.3 for yourself):
./varnishd -a :8033 -b localhost -s file,/usr/pkg/var/varnish.cache,10M -d -d

Enter "start".

Use top(1) to see something like this:
 9920 nobody    25    0  2400K 4296K RUN/1      3:28 97.85% 97.85% varnishd

Enter "param.set diag_bitmap 0x8" and start varnishtop to see this:
4862930.38 Debug          
MTX_UNLOCK(wrk_decimate_flock,cache_pool.c,483,&wq[u]->mtx)
4862930.71 Debug          
MTX_LOCK(wrk_decimate_flock,cache_pool.c,470,&wq[u]->mtx)  

>Fix: