WT-4715 changed WiredTiger to not task application threads that have the oldest transaction ID pinned with helping with eviction, instead, they return WT_ROLLBACK forcing the transaction to abort. This feature is not currently configured for MongoDB because MongoDB doesn't support aborting read-only transactions.

It would be possible to extend this semantic to potentially better support MongoDB by releasing any application thread pinning the oldest transaction ID from participating in eviction, even if we cannot rollback the transaction. The thread would hopefully then proceed forward, eventually releasing the oldest transaction ID. It's possible the thread would further burden the cache, but that might be a reasonable tradeoff for moving the oldest pinned transaction ID forward.