At the moment if WiredTiger gets into a state where it can't evict any pages at all, and all operations are waiting for space in the cache, we can end up waiting forever.

It would be better to exit in that case. Considerations:

• How long do we need to determine we aren't making progress? At least several minutes with 0 evictions.
• Should we consider ourselves stuck if a checkpoint is running? No?
• How to exit. If we leave via a WT_PANIC, it might appear as though the failure could leave the database corrupted. We so far choose not to return WT_ROLLBACK for operations that haven't done an update, and there has been some pushback to adding that.