Look at performance with a green-screen graphic tool.
We had performance problems over the past several weeks where the iSeries would unexplainably slow down. The performance monitor did not trap the problem that caused the system to slow down. Every time the customer service rep's or clients would call to complain, I'd look at the system and the process didn't show up -- presumably because it started and ended to quickly to be trapped by ordinary means. There were no hardware issues (memory or disk) per System Service Tools.
The performance monitor didn't help much. By default the performance monitor is set up to sample the system every 15 minutes and the maximum sampling rate is every five minutes. In order to trap the offending job/task we needed to run a job that samples more frequently and with enough priority so as the offending job wouldn't over power the job that would trap the problem job/task.
To this end, I dragged out an old program that I had found in one of the iSeries rags many years ago. I dusted it off, made some very minor modifications, and let the program do its stuff. Within thirty minutes I "nailed it".
The program (see below) samples the system every five seconds utilizing the Work with System Activity facilities to do the sampling. Not only is the program non-intrusive from a performance point of view, but there is no doubt about which job/task is the culprit.
Work with System Activity (WRKSYSACT) appears to be more current than WRKACTJOB, has more priority and is much less intrusive than sitting at a work station hitting F10 on the WRKACTJOB screen. The program has a much better appearance than the versions of WRKACTJOB or the plain vanilla WRKSYSACT.
I only wish I could give credit to the original author.
Code
Click here to view the DDS code.
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