Vladimir Rodionov created HBASE-14383:
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Summary: Compaction improvements
Key: HBASE-14383
URL: https://issues.apache.org/jira/browse/HBASE-14383
Project: HBase
Issue Type: Improvement
Reporter: Vladimir Rodionov
Assignee: Vladimir Rodionov
Fix For: 2.0.0
Still major issue in many production environments. The general recommendation -
disabling region splitting and major compactions to reduce unpredictable IO/CPU
spikes, especially during peak times and running them manually during off peak
times. Still do not resolve the issues completely.
h3. Flush storms
* rolling WAL events across cluster can be highly correlated, hence flushing
memstores, hence triggering minor compactions, that can be promoted to major
ones.
* the same is true for memstore flushing due to periodic memstore flusher
operation. These events are highly correlated in time if there is a balanced
write-load on the regions in a table.
Both above may produce *flush storms* which are as bad as *compaction storms*.
What can be done here. We can spread these events over time by randomizing
(with jitter) several config options:
# hbase.regionserver.optionalcacheflushinterval
# hbase.regionserver.flush.per.changes
# hbase.regionserver.maxlogs
h3. ExploringCompactionPolicy max compaction size
One more optimization can be added to ExploringCompactionPolicy. To limit size
of a compaction there is a config parameter one could use
hbase.hstore.compaction.max.size. It would be nice to have two separate limits:
for peak and off peak hours.
h3. ExploringCompactionPolicy selection evaluation algorithm
Just seems too simple: selection with more files always wins, selection of
smaller size wins if number of files is the same.
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