>it turns out there will be a dead lock when some
>slow sites are visited. It started the libcurl call, but never time-out,
>effectively lock the semaphore.

BTW, as described, this is not a deadlock. A deadlock is circular
wait -- two things are waiting for each other, so they will wait
forever. This is just a bunch of things all waiting for one thing
(and waiting longer than they're supposed to).

Deadlocks are special. You avoid them in much different ways than
other kinds of undesired waits.

-- 
Bryan Henderson                                    Phone 408-621-2000
San Jose, California