[
https://issues.apache.org/jira/browse/HBASE-14383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14746847#comment-14746847
]
stack commented on HBASE-14383:
-------------------------------
bq. That is very degenerate case.
I do not disagree. Bitch to fix after the fact though.
bq. By default, flush policy ignores all files less than 15MB.
This seems wrong if one of these memstores has an old edit that is holding up
our freeing/GC'ing WALs.
bq. I agree we have to up default value of hbase.regionserver.maxlogs but set
during RS init and not statically.
That sounds reasonable...
bq. MTTR depends not a max number of WAL files but on a current load and PMF
interval.
Disagree. Many WALs has longer MTTR than few WALs
> 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. These events are highly correlated in time if there is a balanced
> write-load on the regions in a table.
> * the same is true for memstore flushing due to periodic memstore flusher
> operation.
> 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
> Too simple? Selection with more files always wins, selection of smaller size
> wins if number of files is the same.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
