What is the role of DSS setting decision/adm/useModelExecutions and page pxModelExecutionResults?
As part of an upgrade effort from 7.3 to 8.3.3 of CDH infrastructure at my customer, we noticed that Pega 8.3 introduced a new page pxModelExecutionResults in the impression structure.
Also there is a new DSS setting introduced "decision/adm/useModelExecutions", whose value by default is true.
When we executed load tests we noticed that memory foot print increased in clipboard pages because of this new page. This is adding almost double the memory print. (255 KB vs 455 KB per container per request) resulting in circuit breaks.
When we tested by setting this DSS to “false” (basically 7.3 mode), we did not face any circuit breaks.
What is the purpose of the new page pxModelExecutionResults?
If it is for additional functionality, can we ignore it for now?
Will there be any issues if we set this flag to “false”?
And do we have to change all DataJoins and GroupBy shapes to exclude this particular page?
1.as of 8.3 we are tracking explicitly which models were executed in the course of one decision as opposed to the implicit way we did it prior to this release. What does this means, you may ask. Every time a model is executed we write and entry in the pxModelExecution results together with any model inputs that originated from the Strategy Result as opposed to an input that came from the Primary Page. When a response is posted on that decision only the models that were used will learn. The setting on the Group By and Data Join is about if you want to consider the models as touched OR not.
2. I advise against you changing that setting. It may lead to incorrect results.
As for an additional 200kb per request causing the decision to miss the SLA, it is possible but is this is happening you should very close to your heap limit. What kind of throughput are we talking about ? At 50 concurrent decisions on a node we're talking an additional 10mb of heap
Replying to this thread for future reference: the Dynamic System Setting decision/adm/useModelExecutions should always be set to true. If you experience any differences in the updating of adaptive models when upgrading from an earlier version to Pega Platform version 8.2 or onwards, please contact Pega Support,