Benjamin Roth created CASSANDRA-13299: -----------------------------------------
Summary: Potential OOMs and lock contention in write path streams Key: CASSANDRA-13299 URL: https://issues.apache.org/jira/browse/CASSANDRA-13299 Project: Cassandra Issue Type: Improvement Reporter: Benjamin Roth I see a potential OOM, when a stream (e.g. repair) goes through the write path as it is with MVs. StreamReceiveTask gets a bunch of SSTableReaders. These produce rowiterators and they again produce mutations. So every partition creates a single mutation, which in case of (very) big partitions can result in (very) big mutations. Those are created on heap and stay there until they are processed. I don't think it is necessary to create a single mutation for each partition. Why don't we implement a PartitionUpdateGeneratorIterator that takes a UnfilteredRowIterator and a max size and spits out PartitionUpdates to be used to create and apply mutations? The max size should be something like min(reasonable_absolute_max_size, max_mutation_size, commitlog_segment_size / 2). reasonable_absolute_max_size could be like 16M or sth. A mutation shouldn't be too large as it also affects MV partition locking. As longer a MV partition is locked during a stream, the higher chances are that WTE's occur during streams. I could also imagine that a max number of updates per mutation regardless of size in bytes could make sense to avoid lock contention. Love to get feedback and suggestions, incl. naming suggestions. -- This message was sent by Atlassian JIRA (v6.3.15#6346)