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https://issues.apache.org/jira/browse/HBASE-9472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13762084#comment-13762084
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Vladimir Rodionov commented on HBASE-9472:
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Just a note. Memstore size of 0.04 is not a good idea. You will end up creating
a lot of tiny flush files and compaction will be running around the clock.
> If the memstore size is under .1 or greater than .9 the memstore size
> defaults to the default memstore size
> -----------------------------------------------------------------------------------------------------------
>
> Key: HBASE-9472
> URL: https://issues.apache.org/jira/browse/HBASE-9472
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.94.5
> Reporter: rahul gidwani
>
> In HbaseConfiguration.checkForClusterFreeMemoryLimit it does a check to see
> if the blockCache + memstore > .8 this threshold ensures we do not run out of
> memory.
> But MemStoreFlusher.getMemStoreLimit does this check:
> {code}
> if (limit >= 0.9f || limit < 0.1f) {
> LOG.warn("Setting global memstore limit to default of " + defaultLimit +
> " because supplied value outside allowed range of 0.1 -> 0.9");
> effectiveLimit = defaultLimit;
> }
> {code}
> In our cluster we had the block cache set to an upper limit of 0.76 and the
> memstore upper limit was set to 0.04. We noticed the memstore size was
> exceeding the limit we had set and after looking at the getMemStoreLimit code
> it seems that the memstore upper limit is sized to the default value if the
> configuration value is less than .1 or greater than .9. This now makes the
> block cache and memstore greater than our available heap.
> We can remove the check for the greater than 90% of the heap as this can
> never happen due to the check in
> HbaseConfiguration.checkForClusterFreeMemoryLimit()
> This check doesn't seem necessary anymore as we have the HbaseConfiguration
> class checking for the cluster free limit. Am I correct in this assumption?
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