Author: Alex Behm <email@example.com>
Date: Fri Dec 2 10:17:22 2016 -0800
IMPALA-4577: Adjust maximum size of row batch queue with MT_DOP.
When MT_DOP is set, non-Parquet scans are run with the old
scan node with a fixed NUM_SCANNER_THREADS=1. This patch
adjust the maximum size of the row batch queue based on MT_DOP
for each such scan instance to avoid a significant increase in
the memory consumption of such scans. The max queued batches
per scan-node instance is at least 2 to always allow for some
parallelism between the producer/consumer.
Decreases the maximum allowed value for MT_DOP from 128 to 64.
Reviewed-by: Alex Behm <firstname.lastname@example.org>
Tested-by: Internal Jenkins