[
https://issues.apache.org/jira/browse/HBASE-1597?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12727054#action_12727054
]
stack commented on HBASE-1597:
------------------------------
This seems odd:
{code}
+ public CompactionReader(Reader reader) {
+ super(reader.istream, reader.fileSize, reader.cache);
+ super.blockIndex = reader.blockIndex;
+ super.trailer = reader.trailer;
+ super.lastkey = reader.lastkey;
+ super.avgKeyLen = reader.avgKeyLen;
+ super.avgValueLen = reader.avgValueLen;
+ super.comparator = reader.comparator;
+ super.metaIndex = reader.metaIndex;
+ super.fileInfoLoaded = reader.fileInfoLoaded;
+ super.compressAlgo = reader.compressAlgo;
+ }
{code}
Why not make a constructor that takes above args?
Too much of readBlock is duplicated in CompactionReader. Would suggest
changing backing readBlock so it makes call to a new method that does the
add-to-cache... then subclass this new method only.
Otherwise, nice patch.
> Prevent unnecessary caching of blocks during compactions
> --------------------------------------------------------
>
> Key: HBASE-1597
> URL: https://issues.apache.org/jira/browse/HBASE-1597
> Project: Hadoop HBase
> Issue Type: Bug
> Affects Versions: 0.20.0
> Reporter: Jonathan Gray
> Assignee: Jonathan Gray
> Fix For: 0.20.0
>
> Attachments: HBASE-1597-v1.patch
>
>
> When running any kind of compaction, we read every block of every storefile
> being compacted into the block cache.
> We would like to reuse any already cached blocks, if available, but otherwise
> we should not bog down the LRU with unnecessary blocks.
> This is not as bad as it was with the old LRU because the latest LRU
> implementation (HBASE-1460) is scan-resistant. This ensures that we are not
> causing massive eviction of the blocks that are being read multiple times or
> from in-memory tables. However, this does add to the GC-woes of an import
> because each block gets further referenced, and for longer periods of time.
> There is also overhead in running the LRU evictions.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
