Hello!

I'm already wrote about my problem there:
http://groups.google.com/group/highload-php-en/browse_thread/thread/f4c3f57ad58b622e

I'm asking FreeBSD people and they point's that this is maybe some
fpm_spinlock() locking issue:
http://lists.freebsd.org/pipermail/freebsd-hackers/2011-February/034295.html

The problem occurs in random range of time with message from backend:
Maximum execution time of 30 seconds exceeded in Unknown on line 0.

And very high VCSW/IVCSW values for php-fpm processes. If i attach to the
hanging fpm processes
then i see that all of them creates many of calls like this:

sched_yield(0x80516c000,0x1,0x4d4828b6,0x8012ef45c,0xffffffff808bfd80,0x7fffffffa078)
= 0 (0x0)
sched_yield(0x80516c000,0x1,0x4d4828b6,0x8012ef45c,0xffffffff808bfd80,0x7fffffffa078)
= 0 (0x0)

Looks like a some infinite loop or such.

How can i debug what's going on to fix the problem? What data should i
provide to localize this issue?
Thanks in advance.

Not sure if it helps, but I only saw an "Unknown on line 0." error message when my custom session handler was throwing exceptions, because session_write_close() is called after the scripts finishes executing.