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https://issues.apache.org/jira/browse/HBASE-8635?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13671127#comment-13671127
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Anoop Sam John commented on HBASE-8635:
---------------------------------------
HBaseConfiguration#checkForClusterFreeMemoryLimit()
{code}
float globalMemstoreLimit =
conf.getFloat("hbase.regionserver.global.memstore.upperLimit", 0.4f);
int gml = (int)(globalMemstoreLimit * CONVERT_TO_PERCENTAGE);
float blockCacheUpperLimit =
conf.getFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY,
HConstants.HFILE_BLOCK_CACHE_SIZE_DEFAULT);
int bcul = (int)(blockCacheUpperLimit * CONVERT_TO_PERCENTAGE);
if (CONVERT_TO_PERCENTAGE - (gml + bcul)
< (int)(CONVERT_TO_PERCENTAGE *
HConstants.HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD)) {
throw new RuntimeException(....)
...
}
{code}
As per this check we need a memory of min 20%(other than the reserved max
spaces) for the functioning of RS. Now in the Trunk gloabl memstore upperlimit
and block cache size are default to 40% making sum to 80%. A default value of
10% to the prefetch scan should be accomodated in this condition.
We need to sacrifice 10% from the block cache?
> Define prefetcher.resultsize.max as percentage
> ----------------------------------------------
>
> Key: HBASE-8635
> URL: https://issues.apache.org/jira/browse/HBASE-8635
> Project: HBase
> Issue Type: Improvement
> Reporter: Ted Yu
> Assignee: Jimmy Xiang
> Priority: Minor
> Attachments: trunk-8635.patch
>
>
> Currently "hbase.hregionserver.prefetcher.resultsize.max" defines global
> limit for prefetching.
> The default value is 256MB.
> It would be more flexible to define this measure as a percentage of the heap.
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