David Logan wrote:
Even though task synchronization and resource serialization are technically different, for the purposes of this discussion, they are essentially the same thing.
Lock, ENQ, latch, etc.serialize update access to any resource being accessed concurrently by two or more asynchronous units of work. An entirely different concept. A much better analog for simple WAIT/POST task synchronization in this context would probably be half-duplex messaging like most 3270 SNA "conversations". (When you press <Enter> your keyboard locks up while the message is sent to, and processed by, the host. The response from the host unlocks your keyboard.)
My point was that anyone that knows how WAIT/POST works can easily make it work, and knows when to acknowledge when that particular tool is beyond is bounds of its ability.
I agree that WAIT/POST -- a service that's been around since OS/360 -- seems simple enough on the surface. But, look how many people on IBM-MAIN are still exhibiting confusion regarding its use -- even about something as fundamental as how/when to clear the ECB! This observation seems to support Chris Craddock's assertion that, even after more than 40 years, the documentation is still quite lacking.
IBM also obviously acknowledged that WAIT/POST was insufficient for all purposes, since other locking mechanisms/serialization mechanisms were created.
If anyone was confused before about WAIT/POST, references to locking/serialization mechanisms in this thread are just making things worse! The point I made was that Pause/Release were introduced, in part, to mitigate known issues with WAIT/POST. Pause/Release is absolutely NOT a locking mechanism!
-- Edward E Jaffe Phoenix Software International, Inc 5200 W Century Blvd, Suite 800 Los Angeles, CA 90045 310-338-0400 x318 [EMAIL PROTECTED] http://www.phoenixsoftware.com/ ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
