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https://issues.apache.org/jira/browse/CASSANDRA-7546?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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graham sanderson updated CASSANDRA-7546:
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Attachment: cassandra-2.1-7546-v3.txt
Oops - my bad - Locks.java wasn't already committed (I though Benedict might
have added it as part of something else), but it turns out I just had it in my
working copy not commit... uploaded cassandra-2.1-7546-v3.txt which adds it back
> AtomicSortedColumns.addAllWithSizeDelta has a spin loop that allocates memory
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-7546
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7546
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: graham sanderson
> Assignee: graham sanderson
> Fix For: 2.1.1
>
> Attachments: 7546.20.txt, 7546.20_2.txt, 7546.20_3.txt,
> 7546.20_4.txt, 7546.20_5.txt, 7546.20_6.txt, 7546.20_7.txt, 7546.20_7b.txt,
> 7546.20_alt.txt, 7546.20_async.txt, 7546.21_v1.txt,
> cassandra-2.1-7546-v2.txt, cassandra-2.1-7546-v3.txt, cassandra-2.1-7546.txt,
> graph2_7546.png, graph3_7546.png, graph4_7546.png, graphs1.png,
> hint_spikes.png, suggestion1.txt, suggestion1_21.txt, young_gen_gc.png
>
>
> In order to preserve atomicity, this code attempts to read, clone/update,
> then CAS the state of the partition.
> Under heavy contention for updating a single partition this can cause some
> fairly staggering memory growth (the more cores on your machine the worst it
> gets).
> Whilst many usage patterns don't do highly concurrent updates to the same
> partition, hinting today, does, and in this case wild (order(s) of magnitude
> more than expected) memory allocation rates can be seen (especially when the
> updates being hinted are small updates to different partitions which can
> happen very fast on their own) - see CASSANDRA-7545
> It would be best to eliminate/reduce/limit the spinning memory allocation
> whilst not slowing down the very common un-contended case.
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