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https://issues.apache.org/jira/browse/HDFS-4979?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Suresh Srinivas updated HDFS-4979:
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Attachment: HDFS-4979.patch
Here is an early patch that adds retry cache to Namenode. Retry is supported
for all the operations except:
* saveNamespace() - if the implementation uses writeLock() instead of
readLock() this can be made idempotent
* create() and append() - want to first get startFileInternal() cleanup from
HDFS-4912.
* updatePipeLine() and deleteSnapshot() can be made idempotent.
This patch currently uses a simple LightWeightGSet for implementing the retry
cache. It currently does not support limiting the number of cache entries or
ejecting entries in the cache based on timeout (design proposed keeping entries
for 10 minutes). The RetryCache should also move common, so that it can be used
by other server that may want to use it.
updatePipeLine can be made idempotent. If the oldBlock and newBlock are same we
could consider it as retried. Checking for node list in the existing block to
the newNodes seems unnecessary. But could be added as an additional check.
{code}
public void updatePipeline(String clientName, ExtendedBlock oldBlock,
ExtendedBlock newBlock, DatanodeID[] newNodes)
throws IOException;
{code}
> Implement retry cache on the namenode
> -------------------------------------
>
> Key: HDFS-4979
> URL: https://issues.apache.org/jira/browse/HDFS-4979
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: namenode
> Reporter: Suresh Srinivas
> Attachments: HDFS-4979.patch
>
>
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