Re: HTTP API or Web Service concurrency issue

Hi Charles,

Thanks for that temp file API tip. I'll be using it.

I wrote a simple program obtaining a timestamp, and recording it into a
file. I simultaneously ran two instances of that program, and was able to
reproduce the capture of identical timestamps. Apparently, the developer
had wishful thinking that a timestamp precision of 6 fractional seconds
would be unique.

Each copy of the test program wrote 500,000 timestamps to a file, for a
total of 1,000,000, and to my surprise, a healthy volume of 2,687 duplicate
timestamps were captured.

I'm glad this is the problem, because the fix is an easy one.

Scott + Charles + Nathan -> have a great weekend and thank you again for
your help.

Mike

On Fri, May 31, 2019 at 4:06 PM Charles Wilt <charles.wilt@xxxxxxxxx> wrote:

On Fri, May 31, 2019 at 2:54 PM Mike Jones <mike.jones.sysdev@xxxxxxxxx>
wrote:

In step a.1, the IFS output file created contains a timestamp in the file
name, with a precision of 6 fractional seconds. That should do a very

good

job ensuring a unique file name, but I see that as a potential problem
where 2 jobs could, in theory, obtain the same exact timestamp, and

collide

on the IFS output file name. I'll likely recommend shoring that up to
ensure uniqueness.

Yeah...that could be a problem...

Take a look at the tmpfile() — Create Temporary File API
https://www.ibm.com/support/knowledgecenter/ssw_ibm_i_72/rtref/tempfile.htm
IIRC, HTTP API even makes use of it...

Charles
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