> I’m not sure I agree that the ONLY 4D command in the language that is atomic is “Semaphore”. > I’m guessing there are others. Gonna need a 4D engineer like Laurent Esnault that knows the > deep internals of 4D’s code to know for sure.
For what it's worth, I was working at 4D in Cupertino when 4D Server shipped. We had big arguments in the US office about IP communications and semaphores. (Most people really don't love semaphores.) Semaphores turned out to be the one and only reliable mechanism available. Unless something has changed, that's still going to be true. I'm sure there are a narrow set of cases where not using semaphores to lock a shared read-write resource won't cause any harm. It's easy to come up with cases and I'd bet we all have some of each. Say you have an IP variable like <>TAB and you assign in Char(13) more than once. No harm. But for groups of arrays (or even single arrays), it's pretty much not save to read or write without a lock unless the arrays are static. And it's *totally* normal to have a static array. Initialize it once at startup (or on first use) and that's it. No modifications, just lookups. No elements change position or value, the array never changes size. (Some languages have a construct for this type of list, we just have arrays and how we use them.) No need for a semaphore there either. I guess the rule is: If you think that you might need a semaphore lock, you do ;-) ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:4d_tech-unsubscr...@lists.4d.com **********************************************************************
