Eshcar Hillel updated HBASE-18294:
A region is flushed if its memory component exceeds the region flush threshold.
A flush policy decides which stores to flush by comparing the size of the store
to a column-family-flush threshold.
If the overall size of all memstores in the machine exceeds the bounds defined
by the administrator (denoted global pressure) a region is selected and flush.
HBASE-18294 changes flush decisions to be based on heap-occupancy and not data
(key-value) size, consistently across levels. This rolls back some of the
changes by HBASE-16747. Specifically,
(1) RSs, Regions and stores track their overall on-heap and off-heap occupancy,
(2) A region is flushed when its on-heap+off-heap size exceeds the region flush
(3) The store to be flushed is chosen based on its on-heap+off-heap size
(4) At the RS level, a flush is triggered when the overall on-heap exceeds the
on-heap limit, or when the overall off-heap size exceeds the off-heap limit
(low/high water marks).
Note that when the region flush size is set to XXmb a region flush may be
triggered even before writing keys and values of size XX because the total heap
occupancy of the region which includes additional metadata exceeded the
> 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-18294.01.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, 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
> 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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