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https://issues.apache.org/jira/browse/HDFS-16261?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Bryan Beaudreault updated HDFS-16261:
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Description:
When a block is moved with REPLACE_BLOCK, the new location is recorded in the
NameNode and the NameNode instructs the old host to in invalidate the block
using DNA_INVALIDATE. As it stands today, this invalidation is async but tends
to happen relatively quickly.
I'm working on a feature for HBase which enables efficient healing of locality
through Balancer-style low level block moves (HBASE-26250). One issue is that
HBase tends to keep open long running DFSInputStreams and moving blocks from
under them causes lots of warns in the RegionServer and increases long tail
latencies due to the necessary retries in the DFSClient.
One way I'd like to fix this is to provide a configurable grace period on async
invalidations. This would give the DFSClient enough time to refresh block
locations before hitting any errors.
was:
When a block is moved with REPLACE_BLOCK, the new location is recorded in the
NameNode and the NameNode instructs the old host to in invalidate the block
using DNA_INVALIDATE. As it stands today, this invalidation is async but tends
to happen relatively quickly.
I'm working on a feature for HBase which enables efficient healing of locality
through Balancer-style low level block moves. One issue is that HBase tends to
keep open long running DFSInputStreams and moving blocks from under them causes
lots of warns in the RegionServer and increases long tail latencies due to the
necessary retries in the DFSClient.
One way I'd like to fix this is to provide a configurable grace period on async
invalidations. This would give the DFSClient enough time to refresh block
locations before hitting any errors.
> Configurable grace period around deletion of invalidated blocks
> ---------------------------------------------------------------
>
> Key: HDFS-16261
> URL: https://issues.apache.org/jira/browse/HDFS-16261
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Bryan Beaudreault
> Assignee: Bryan Beaudreault
> Priority: Major
>
> When a block is moved with REPLACE_BLOCK, the new location is recorded in the
> NameNode and the NameNode instructs the old host to in invalidate the block
> using DNA_INVALIDATE. As it stands today, this invalidation is async but
> tends to happen relatively quickly.
> I'm working on a feature for HBase which enables efficient healing of
> locality through Balancer-style low level block moves (HBASE-26250). One
> issue is that HBase tends to keep open long running DFSInputStreams and
> moving blocks from under them causes lots of warns in the RegionServer and
> increases long tail latencies due to the necessary retries in the DFSClient.
> One way I'd like to fix this is to provide a configurable grace period on
> async invalidations. This would give the DFSClient enough time to refresh
> block locations before hitting any errors.
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