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https://issues.apache.org/jira/browse/HDFS-6227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13966878#comment-13966878
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Colin Patrick McCabe commented on HDFS-6227:
--------------------------------------------
bq. I quickly checked the code, in ShortCircuitCache#unref, we close the
replica when the ref count is 0, but I did not find the corresponding code to
remove the replica object. Thus is it possible that the cause of the issue is a
closed ShortCircuitReplica object was still retrieved from the
ShortCircuitCache and used for reading? Colin Patrick McCabe, could you provide
some input?
That should not be possible. See this code in {{ShortCircuitCache#unref}}:
{code}
int newRefCount = --replica.refCount;
if (newRefCount == 0) {
// Close replica, since there are no remaining references to it.
Preconditions.checkArgument(replica.purged,
"Replica " + replica + " reached a refCount of 0 without " +
"being purged");
replica.close();
{code}
Notice that we would throw a precondition exception if the replica hadn't been
purged. ("Purged" means that it has been removed from the cache and will not
be handed out to new readers.) There is no other path to calling
{{ShortCircuitReplica#close}}.
Can you say a little bit more about the platform and version that you saw this
on? Can you reproduce it? Also, are there any other messages in the log?
> Short circuit read failed due to ClosedChannelException
> -------------------------------------------------------
>
> Key: HDFS-6227
> URL: https://issues.apache.org/jira/browse/HDFS-6227
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.4.0
> Reporter: Jing Zhao
>
> While running tests in a single node cluster, where short circuit read is
> enabled and multiple threads may read the same file concurrently, one of the
> read got ClosedChannelException and failed. Full exception trace see comment.
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