🚀 go-pugleaf

>
>They do need to share a common instance of the critical section or semaphor,
>and they both need to use it in order to properly protect the shared data in
>a synchronized manner.  Without it, one thread could be reading the data at
>the exact same moment that another thread is altering the data.
>

It is not exactly because it's not clear from task when and how 
threads will work with variable.

For example both threads access to variable asynchronous. Look.

One thread modyfyes variable in 10:00 and 10:05.

Another thread may read in 9:58, 10:02, 10:07. In every of cases it 
will be various value of variables undependenly of using or 
not using critical sections. If this threads doesn't know 
exactly when data was changed it may read it in any time or 
it must carefully track for changes. Critical sections doesn't 
help for tracking changes (or it must be called continuously).
I only say that it is not important to enter in critical section if unknown when changes were. Reading thread can 
enter before first writing or after but really reading thread 
must all time "listen" variable via critical section or semaphor. Or it is incorrect?
Vladimir.