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Ekaterina Dimitrova commented on CASSANDRA-16318: ------------------------------------------------- Patch [here |https://github.com/ekaterinadimitrova2/cassandra/pull/80] CI run: [Java 8 |https://app.circleci.com/pipelines/github/ekaterinadimitrova2/cassandra/545/workflows/f797bf58-b572-4d8c-831e-a61936d23624] and [Java 11 |https://app.circleci.com/pipelines/github/ekaterinadimitrova2/cassandra/545/workflows/6dbe4bca-b51d-473e-bfc4-1bbf6c4ff26d] >From the preliminary test I pushed looks like the issue was solved. I will >check/publish full report of the microbench tests when I am back to the office >on the 4th January. > Memtable heap size is severely underestimated > --------------------------------------------- > > Key: CASSANDRA-16318 > URL: https://issues.apache.org/jira/browse/CASSANDRA-16318 > Project: Cassandra > Issue Type: Bug > Components: Local/Memtable > Reporter: Branimir Lambov > Assignee: Ekaterina Dimitrova > Priority: Normal > Fix For: 4.0-beta > > Attachments: image-2020-12-09-10-57-21-994.png, > image-2020-12-09-11-01-31-273.png > > > We seem to be estimating the size of the on-heap memtable metadata to be > around half of what it actually is. For example, during a [read benchmark > which writes 1 million single-long > rows|https://github.com/blambov/cassandra/blob/memtable-heap/test/microbench/org/apache/cassandra/test/microbench/instance/ReadTestSmallPartitions.java] > the memtable reports > {code} > 1000000 ops, 58.174MiB serialized bytes, 385.284MiB (19%) on heap, 0.000KiB > (0%) off-heap > {code} > while a heap dump taken at this point: > !image-2020-12-09-10-57-21-994.png! > lists an usage of about 666MB altogether. > Switching to {{offheap_objects}}, the reported numbers are > {code} > 1000000 ops, 58.174MiB serialized bytes, 233.650MiB (12%) on heap, 53.406MiB > (3%) off-heap > {code} > while actual heap usage: > !image-2020-12-09-11-01-31-273.png! > is about 442MB. > Looking at the code we definitely are not counting the > {{AtomicBTreePartition.Holder}}, {{EncodingStats}}, liveness and deletion > info objects associated with each partition, and most probably others. -- 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