I have some query logic that uses a stack of custom iterators with a
batch scanner. The query begins to return values but then stops with a
'scanner closed' error. The only reference I can find to scanner closed
in the src is in TabletServerBatchReaderIterator. I can see that the

error is thrown when the query thread pool is shutdown, but I am not
sure why this is happening. This query logic works on a single node
instance, but I get the scanner closed error when running on a multi-node
cluster.

So far the stack traces have not been very helpful and we are not sure
where or how to troubleshoot this. Any info on what conditions would
lead to a scanner closed error and where to begin looking to resolve
would be appreciated.

Thanks,