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Marcus Eriksson commented on CASSANDRA-16201: --------------------------------------------- [~tsteinmaurer] you sure you don't see this in 3.11? looks like we ignore {{initialCapacity}} in 3.0 here: https://github.com/apache/cassandra/blob/cassandra-3.0/src/java/org/apache/cassandra/utils/btree/BTree.java#L752 but not in 3.11: https://github.com/apache/cassandra/blob/cassandra-3.11/src/java/org/apache/cassandra/utils/btree/BTree.java#L777 > Cassandra 4.0 b2 - OOM / memory pressure due to object array pre-allocations > in BatchUpdatesCollector > ----------------------------------------------------------------------------------------------------- > > Key: CASSANDRA-16201 > URL: https://issues.apache.org/jira/browse/CASSANDRA-16201 > Project: Cassandra > Issue Type: Bug > Reporter: Thomas Steinmaurer > Priority: Normal > Attachments: screenshot-1.png > > > In a Cas 2.1 / 3.0 / 3.11 / 4.0b2 comparison test with the same load profile, > we see 4.0b2 going OOM from time to time. According to a heap dump, we have > multiple NTR threads in a 3-digit MB range. > This is likely related to object array pre-allocations at the size of > {{BatchUpdatesCollector.updatedRows}} per {{BTree}} although there is always > only 1 {{BTreeRow}} in the {{BTree}}. > !screenshot-1.png! > So it seems we have many, many 20K elemnts pre-allocated object arrays > resulting in a shallow heap of 80K each, although there is only one element > in the array. > This sort of pre-allocation is causing a lot of memory pressure. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org