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https://issues.apache.org/jira/browse/HDFS-1262?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12882609#action_12882609
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sam rash commented on HDFS-1262:
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hey, so what should the precise semantics of abandonFile(String src, String
holder) be? I have a quick impl now (+ test case) that does this:
1. check that holder owns the lease for src
2. call internalReleaseLeaseOne
so it really is a glorified 'cleanup and close' which has the same behavior as
if the lease expired--nice and tidy imo. It does have the slight delay of
lease recovery, though.
an alternative option:
for the specific case we are fixing here, we could do something simpler such as
just putting the targets in the blockMap and call completeFile (basically what
commitBlockSynchronization would do). However, this doesn't handle the general
case if we expose abandonFile at any other time and a client has actually
written data to last block.
I think the first option is safer, but maybe I'm too cautious
if the way I've implemented it seems ok, I can post he patch for review asap
> Failed pipeline creation during append leaves lease hanging on NN
> -----------------------------------------------------------------
>
> Key: HDFS-1262
> URL: https://issues.apache.org/jira/browse/HDFS-1262
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs client, name-node
> Affects Versions: 0.20-append
> Reporter: Todd Lipcon
> Assignee: sam rash
> Priority: Critical
> Fix For: 0.20-append
>
>
> Ryan Rawson came upon this nasty bug in HBase cluster testing. What happened
> was the following:
> 1) File's original writer died
> 2) Recovery client tried to open file for append - looped for a minute or so
> until soft lease expired, then append call initiated recovery
> 3) Recovery completed successfully
> 4) Recovery client calls append again, which succeeds on the NN
> 5) For some reason, the block recovery that happens at the start of append
> pipeline creation failed on all datanodes 6 times, causing the append() call
> to throw an exception back to HBase master. HBase assumed the file wasn't
> open and put it back on a queue to try later
> 6) Some time later, it tried append again, but the lease was still assigned
> to the same DFS client, so it wasn't able to recover.
> The recovery failure in step 5 is a separate issue, but the problem for this
> JIRA is that the NN can think it failed to open a file for append when the NN
> thinks the writer holds a lease. Since the writer keeps renewing its lease,
> recovery never happens, and no one can open or recover the file until the DFS
> client shuts down.
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