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https://issues.apache.org/jira/browse/HBASE-18294?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16353979#comment-16353979
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Edward Bortnikov commented on HBASE-18294:
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[~eshcar], [~anoop.hbase], [~ram_krish], maybe we can take the following
approach to your dispute on RB.
The code makes the following config variable definitions:
{code:java}
public static final String HREGION_MEMSTORE_FLUSH_SIZE =
"hbase.hregion.memstore.flush.size";
public static final String HREGION_MEMSTORE_OFFHEAP_FLUSH_SIZE =
"hbase.hregion.memstore.offheap.flush.size";{code}
The former is the legacy flush size threshold, whereas the latter is new.
However, the further treatment is different - HREGION_MEMORY_FLUSH_SIZE is
actually treated as *on-heap* threshold. This is confusing I guess - especially
for admins.
Having said that, we do need separate accounting for on-heap and off-heap
memory, as [~eshcar] explained above. Let me suggest a change that is more
digestible for users imo. Let HREGION_MEMORY_FLUSH_SIZE retain its legacy
meaning (and the 128M default) - namely, the overall max memory the system is
willing to allocate for a store. Furthermore, let's define a new variable,
HREGION_MEMSTORE_OFFHEAP_SIZE_RATIO, to define a fraction of the former that
can be allocated offheap (0, by default).
How about that?
> Reduce global heap pressure: flush based on heap occupancy
> ----------------------------------------------------------
>
> Key: HBASE-18294
> URL: https://issues.apache.org/jira/browse/HBASE-18294
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 3.0.0
> Reporter: Eshcar Hillel
> Assignee: Eshcar Hillel
> Priority: Major
> Fix For: 2.0.0-beta-2
>
> Attachments: HBASE-18294.01.patch, HBASE-18294.01.patch,
> HBASE-18294.01.patch, HBASE-18294.01.patch, HBASE-18294.02.patch,
> HBASE-18294.03.patch, HBASE-18294.04.patch, HBASE-18294.05.patch,
> HBASE-18294.06.patch, HBASE-18294.07.patch, HBASE-18294.07.patch,
> HBASE-18294.08.patch, HBASE-18294.09.patch, HBASE-18294.10.patch,
> HBASE-18294.11.patch, HBASE-18294.11.patch, HBASE-18294.12.patch,
> HBASE-18294.13.patch, HBASE-18294.15.patch, HBASE-18294.16.patch,
> HBASE-18294.master.01.patch
>
>
> A region is flushed if its memory component exceed a threshold (default size
> is 128MB).
> A flush policy decides whether to flush a store by comparing the size of the
> store to another threshold (that can be configured with
> hbase.hregion.percolumnfamilyflush.size.lower.bound).
> Currently the implementation (in both cases) compares the data size
> (key-value only) to the threshold where it should compare the heap size
> (which includes index size, and metadata).
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