Thanks for the careful notes Peter.  My initial interest here is for 
single-threaded batch applications. But the extension to multi-threaded ones 
obviously raises the issues you described.

Peter

From: IBM Mainframe Discussion List <[email protected]> On Behalf Of 
Peter Relson
Sent: Monday, February 19, 2024 10:03 AM
To: [email protected]
Subject: Re: Nanosecond resolution timestamps for HLL's?


It might be said that the notion of monotonicity with respect to clock values 
is not "valid" unless you are a single-threaded application or all your 
references are serialized across all the threads (such as by a step- or system- 
or systems-level ENQ depending on the characteristics).



Otherwise you cannot possibly tell what is what because thread one might have 
captured clock value "n" and then gotten interrupted, and then thread two 
captured clock value "n+1" and then continued to completion, after which thread 
one was re-dispatched (with what is now an older time stamp than the one 
already captured).



If these two threads were serialized by an ENQ against each other the above 
scenario would not happen because thread two would not have been able to get to 
the point of capturing its clock value.



Peter Relson

z/OS Core Technology Design

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