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ZhaoYang commented on CASSANDRA-13299: -------------------------------------- Thanks for the feedback. Rebased with lastest trunk, dtest is unstable due to netty.. bq. Make ThrottledUnfilteredIterator an Iterator<UnfilteredRowIterator> instead of using hasNextGroup and resetLimit which is analogous to hasNext and next. Extended {{AbstractIterator<UnfilteredRowIterator>}} and implements {{computeNext()}} {quote} Move to org.apache.cassandra.db.rows package Add simple javadoc explaining what it does Move cassandra.mv.mutation.row.count out of ThrottledUnfilteredIterator, and maybe rename it to cassandra.repair.mutation_repair_rows_per_batch (or similar, since it's also used for CDC). {quote} +1 fixed bq. Add unit test to ThrottledUnfilteredIterator to make sure it's generating range tombstones correctly Added {{ThrottledUnfilteredIteratorTest}} > 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 > Assignee: ZhaoYang > > 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 finished > processing. > 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. > The 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 (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org