[
https://issues.apache.org/jira/browse/HBASE-15378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15182580#comment-15182580
]
Phil Yang commented on HBASE-15378:
-----------------------------------
We will continue the loop if it is heartbeat and cache is empty. If cache is
not empty, we can return cached data to user.
{code}
if (callable.isHeartbeatMessage()) {
if (cache.size() > 0) {
// Caller of this method just wants a Result. If we see a heartbeat
message, it means
// processing of the scan is taking a long time server side. Rather
than continue to
// loop until a limit (e.g. size or caching) is reached, break out
early to avoid causing
// unnecesary delays to the caller
if (LOG.isTraceEnabled()) {
LOG.trace("Heartbeat message received and cache contains Results."
+ " Breaking out of scan loop");
}
break;
}
continue;
}
{code}
> Scanner can not handle a heartbeat message with no results
> ----------------------------------------------------------
>
> Key: HBASE-15378
> URL: https://issues.apache.org/jira/browse/HBASE-15378
> Project: HBase
> Issue Type: Bug
> Components: dataloss, Scanners
> Affects Versions: 1.2.0, 1.1.3
> Reporter: Phil Yang
> Assignee: Phil Yang
> Priority: Critical
> Attachments: HBASE-15378-v1.txt, HBASE-15378-v2.txt,
> HBASE-15378-v3.txt
>
>
> When a RS scanner get a TIME_LIMIT_REACHED_MID_ROW state, they will stop
> scanning and send back what it has read to client and mark the message as a
> heartbeat message. If there is no cell has been read, it will be an empty
> response.
> However, ClientScanner only handles the situation that the client gets an
> empty heartbeat and its cache is not empty. If the cache is empty too, it
> will be regarded as end-of-region and open a new scanner for next region.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
