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https://issues.apache.org/jira/browse/HDFS-4495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13577700#comment-13577700
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Kihwal Lee commented on HDFS-4495:
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Allowing clients to renew leases past the soft limit is acceptable. The lease
soft limit is used by lease recovery and the way it works guarantees that no
two writers are writing to the same file or block. When lease recovery is
triggered by create() the file is recreated, so any activity on the old RBW
block won't interfere with the new file. If append() causes a lease recovery, a
block recovery is forced against the last RBW block and until it is done client
gets RecoveryInProgressException. As a part of block recovery, existing
writers are terminated and a new generation number is stamped on the block, so
any existing client won't be able to write any longer. A client explicitly
calling recoverLease() also works similarly.
> Allow client-side lease renewal to be retried beyond soft-limit
> ---------------------------------------------------------------
>
> Key: HDFS-4495
> URL: https://issues.apache.org/jira/browse/HDFS-4495
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 2.0.3-alpha, 0.23.5
> Reporter: Kihwal Lee
>
> The current lease renewal code in DFSClient gives up after several retries,
> if the soft limit exceeds. This causes the client to abort. Without this
> self destruction behavior, lease renewal can be retried infinitely due to
> unrelated low-level issue and prevent DFSClient and associated Connection
> from getting garbage collected.
> However, giving up at passage of the soft limit has been shown to be too
> fragile; A long GC on namenode or transient network outage can make clients
> fail. We need the self-destruct behavior, but clients should be allowed to
> retry for longer period of time.
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