[ https://issues.apache.org/jira/browse/CASSANDRA-16201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17253586#comment-17253586 ]
Marcus Eriksson commented on CASSANDRA-16201: --------------------------------------------- rebased the branches and fixed Yifans comments (not all, but the non-style ones) Also pushed another commit to the branches improving this a bit more - in the 3.0 case it is a slightly smaller backport of CASSANDRA-12153 to avoid allocating the LinkedHashSet every time we iterate the restrictions. [~blerer] - any chance you have time to review this? > Reduce amount of allocations during batch statement execution > ------------------------------------------------------------- > > Key: CASSANDRA-16201 > URL: https://issues.apache.org/jira/browse/CASSANDRA-16201 > Project: Cassandra > Issue Type: Bug > Components: Local/Other > Reporter: Thomas Steinmaurer > Assignee: Marcus Eriksson > Priority: Normal > Fix For: 3.0.x, 3.11.x, 4.0-beta > > Attachments: 16201_jfr_3023_alloc.png, 16201_jfr_3023_obj.png, > 16201_jfr_3118_alloc.png, 16201_jfr_3118_obj.png, 16201_jfr_40b3_alloc.png, > 16201_jfr_40b3_obj.png, screenshot-1.png, screenshot-2.png, screenshot-3.png, > screenshot-4.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|width=100%! > 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