Setting a deep array index (for example, $set: {“a.1500001”: 1}) forces path_support.cpp::maybePadTo to append up to 1.5 million null BSON elements to the array one at a time in a loop without interrupt checks. We can easily remediate this by adding a periodic check inside maybePadTo().

Add periodic check in maybePadTo(). There is already a stage in the delinquency workload that tracks this behavior; run that workload on master to ensure it reproduces delinquency. After adding the check, run it again and see if delinquency is avoided. Finally, run the required sys-perf suite to ensure no regressions occur.