cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "graham sanderson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7546) AtomicSortedColumns.addAllWithSizeDelta has a spin loop that allocates memory
Date Tue, 16 Sep 2014 15:56:34 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14135637#comment-14135637
] 

graham sanderson commented on CASSANDRA-7546:
---------------------------------------------

Ok, thanks Sylvain, yes I was a bit confused (also because Benedict's changes included in
the incorrect tag had CHANGES.txt with his new stress change as part of listed 2.1.0 changes
- which of course now makes sense); anyways... this is good news for me, I'll leave the test
cluster on what I deployed (2.1.0-tentative == the real 2.1.0 as expected according to how
the vote was looking at the time), and update stress.jar on my load machine to come from 2.1
head.

> 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,
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.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message