Trans wrote:
> In sync.rb what are Sync::UN, Sync::EX and Sync::SH all about?

EX is exclusive: if a thread requests an EX lock, no other threads may 
may hold the lock at the same time.

SH is shared: many threads may hold the lock as long as they all 
requested a shared lock.

The intent is to allow either multiple readers or a single writer (but 
not both) inside the critical section(s) of code.

-- 
        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407