Gil - Thanks.
> It's not clear what your objective is -- apparentlly you have some recurrent event and an > indeterminate number of tasks each of which must execute exactly once for each occurrence of that event I have z/OS tasks of all stripes driving a z/OS system exit. I have a finite supply of a resource that each task needs in the exit. Sometimes the resources are exhausted and will not be replenished for a while. What if we come through the exit and are out of the resources? It would be nice if all of the tasks in such a situation could wait until the resource was replenished, without each task having to do a GETMAIN or CPOOL GET, chaining it to the previous (not a trivial thing in a totally asynchronous multi-CPU situation), WAITing, and then unchaining the block and freeing it. It might be nice if there were a single control block on which all of the tasks could (effectively) "wait." I think it ain't gonna happen. I hear the ENQ solutions -- and yes, I asked for possibly an ENQ solution -- but I think the complexity exceeds the benefit at this point. I do have a design alternative to "waiting." The finite resource is a CPOOL in CSA. An alternative is to let it expand. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Paul Gilmartin Sent: Sunday, May 06, 2012 2:04 PM To: [email protected] Subject: Re: Multiple waiting tasks, one control block? On Sun, 6 May 2012 09:27:22 -0700, Charles Mills wrote: > >I am kicking the ENQ idea around. ENQ is certainly promising. There are >some interlock issues with re-establishing the exclusive ENQ after >relinquishing it, and what do the intended waiting tasks do in the >meantime, but it has promise. > Two tasks, A and B alternately ENQing EXC. (Synchronize with WAIT/POST. B issues ENQ EXC, then A DEQs. All tasks with ENQ SHR are now free to run. There will always be at least one, sometimes two ENQ EXC outstanding. It's not clear what your objective is -- apparentlly you have some recurrent event and an indeterminate number of tasks each of which must execute exactly once for each occurrence of that event ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
