> Define application program? COBOL batch or CICS transaction program? > Most legacy applications on z/OS don't implement concurrency.
Agreed, they don't implement concurrency, however they are often very heavily reliant upon on it, as it is built into the database management and message queuing systems they access (whether the programmer is aware of it or not). As a result, workloads generally move right along. -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of David Crayford Sent: Monday, October 21, 2019 11:16 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Best way for a task to give up the CPU and let other tasks run? Caution! This message was sent from outside your organization. On 2019-10-22 1:55 AM, Tony Harminc wrote: > On Sun, 20 Oct 2019 at 02:32, David Crayford <dcrayf...@gmail.com> wrote: > >> The only code I've seen that implements yield are synchronization >> routines. Consider a spin-lock which is spinning on a CS instruction. > Why would any application program on z/OS implement and use a spin > lock? Define application program? COBOL batch or CICS transaction program? Most legacy applications on z/OS don't implement concurrency. Porting modern code is another matter. You may find a lot of the new ported code like Node.js (V8), libuv etc implement their own locks. > Why do the authors of such think they can do a better implementation > than the operating system? Maybe using SETLOCK (which requires supervisor state, key 0) is an obstacle? > > If you think you need a spin lock on z/OS, you should probably be > using transactional execution. Yes, I agree. But it's quite tricky to grok and you need to crack open the assembler! There's an example of a lock-free queue using transactional execution in Zowe https://github.com/zowe/zowe-common-c/blob/719251839033059fb3b507f26f6fbb58be57f188/c/collections.c#L1123 > > Tony H. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
