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https://issues.apache.org/jira/browse/HBASE-70?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12576315#action_12576315
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stack commented on HBASE-70:
----------------------------
Up on IRC, Bryan suggests we look into using PhantomReferences for Memcache.
Phantoms run a callback just before item is collected. An objection was
running flush in a low-memory situation would be risky. The counter was yes,
true, but the alternative is us writing a mechanism similiar to Phantoms and
that we should try the built-in mechanism first if only to learn how not to do
it.
> [hbase] memory management
> -------------------------
>
> Key: HBASE-70
> URL: https://issues.apache.org/jira/browse/HBASE-70
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: stack
>
> Each Store has a Memcache of edits that is flushed on a fixed period (It used
> to be flushed when it grew beyond a limit). A Region can be made up of N
> Stores. A regionserver has no upper bound on the number of regions that can
> be deployed to it currently. Add to this that per mapfile, we have read the
> index into memory. We're also talking about adding caching of blocks and
> cells.
> We need a means of keeping an account of memory usage adjusting cache sizes
> and flush rates (or sizes) dynamically -- using References where possible --
> to accomodate deployment of added regions. If memory is strained, we should
> reject regions proffered by the master with a resouce-constrained, or some
> such, message.
> The manual sizing we currently do ain't going to cut it for clusters of any
> decent size.
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