When you see an entry such as this in a PegaRULES log file: "Unable to synchronize on requestor HCD7095BA4BA8147CBF9D9E4245B50B5C within 120 seconds" and need to find the pyUserIdentifier you can use either of the following techniques:
1) Build a report definition in the Log-Usage class that returns .pyUserIdentifier (at least) and filters based on .pxRequestorID (at least). It is better if the report includes the .pxSnapshotTime and also uses the same as a filter. That way you can narrow your results to what you want. The requestor ID can be paramaterized so that the filter conditions do not have to be modified.
2) Use the following SQL:
select pyUserIdentifier, pxSystemNode, pxSnapshotTime from pr_perf_stats
where pxSnapshotTime between to_date ('2015-09-23', 'yyyy-mm-dd') and to_date ('2015-09-25', 'yyyy-mm-dd')
You will need to input your specific dates of course.