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https://issues.apache.org/jira/browse/CASSANDRA-1214?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis updated CASSANDRA-1214:
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Attachment: 1214-v3.txt
patch that uses JNA, with catch for various error conditions and more
informative logging where possible.
As discussed above, we can't ship JNA with Cassandra but we can pull it in with
ivy at build time. So one of the conditions handled is simply "JNA doesn't
exist at runtime." (But we don't need to resort to reflection to allow it to
compile without JNA.) [A sufficiently recent version of JNA is not available
in the main public maven repo, and that won't change in the near future, so we
will host one on Riptano's repo. I will update this patch when that is ready.]
> Force linux to not swap the JVM
> -------------------------------
>
> Key: CASSANDRA-1214
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1214
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: James Golick
> Fix For: 0.6.5
>
> Attachments: 1214-v3.txt, mlockall-jna.patch.txt, Read Throughput
> with mmap.jpg, trunk-1214.txt
>
>
> The way mmap()'d IO is handled in cassandra is dangerous. It allocates
> potentially massive buffers without any care for bounding the total size of
> the program's buffers. As the node's dataset grows, this *will* lead to
> swapping and instability.
> This is a dangerous and wrong default for a couple of reasons.
> 1) People are likely to test cassandra with the default settings. This issue
> is insidious because it only appears when you have sufficient data in a
> certain node, there is absolutely no way to control it, and it doesn't at all
> respect the memory limits that you give to the JVM.
> That can all be ascertained by reading the code, and people should certainly
> do their homework, but nevertheless, cassandra should ship with sane defaults
> that don't break down when you cross some magic unknown threshold.
> 2) It's deceptive. Unless you are extremely careful with capacity planning,
> you will get bit by this. Most people won't really be able to use this in
> production, so why get them excited about performance that they can't
> actually have?
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