The chances of two jobs writing to the file are slim and none I am searching
a large number of files because I cannot find the data

 And most importantly it is NOT a production job 

thanks

-----Original Message-----
From: IBM Mainframe Discussion List <[email protected]> On Behalf Of
Jeremy Nicoll
Sent: Friday, March 26, 2021 9:13 AM
To: [email protected]
Subject: Re: Dataset contention

On Fri, 26 Mar 2021, at 12:38, Joseph Reichman wrote:

> The output file is shared among multiple jobs whenever I get an equal 
> condition I open put and close

That won't work if two jobs simultaneously try to write to the file.

You might not destroy the file, but you will lose the information that the
second job tried to write to it.

The jobs need 

(a) not to allocate the output dataset at all in the JCL

(b) to have a retry loop that does something like the
    following when you want to write data out

   repeat
       try to get exclusive use of the results file
       if that fails and we've tried many times,
          perhaps write the data somewhere else?
           - though that might also fail
          stop trying
       end

       if exclusive use isn't acquired but we've not tried
          often, wait a bit (a random time interval) and 
          try again

       if exclusive use was granted, update the file,
          free it again, and stop trying
    end



--
Jeremy Nicoll - my opinions are my own.

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