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https://issues.apache.org/jira/browse/HBASE-8420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13665774#comment-13665774
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Ted Yu commented on HBASE-8420:
-------------------------------
bq. So, no matter what the cancel returns, as long as we deduct
prefetchedResultSize, it will be good.
Looking at
http://javasourcecode.org/html/open-source/jdk/jdk-6u23/java/util/concurrent/Future.java.html
, starting line 73.
{code}
* @param mayInterruptIfRunning <tt>true</tt> if the thread executing this
* task should be interrupted; otherwise, in-progress tasks are allowed
* to complete
{code}
Since false is passed to cancel(), by the time we reach:
{code}
+ if (prefetchedResultSize > 0) {
{code}
prefetchedResultSize may be 0 (yet to be filled by the running thread). We
would miss the upcoming assignment to prefetchedResultSize.
> Port HBASE-6874 Implement prefetching for scanners from 0.89-fb
> -----------------------------------------------------------------
>
> Key: HBASE-8420
> URL: https://issues.apache.org/jira/browse/HBASE-8420
> Project: HBase
> Issue Type: Improvement
> Reporter: Jimmy Xiang
> Assignee: Jimmy Xiang
> Attachments: 0.94-8420_v1.patch, 0.94-8420_v2.patch,
> trunk-8420_v1.patch, trunk-8420_v2.patch, trunk-8420_v3.patch,
> trunk-8420_v4.patch, trunk-8420_v5.1.patch, trunk-8420_v5.patch,
> trunk-8420_v6.patch
>
>
> This should help scanner performance. We should have it in trunk.
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