Josh Elser created HBASE-21915:
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             Summary: FileLink$FileLinkInputStream doesn't implement CanUnbuffer
                 Key: HBASE-21915
                 URL: https://issues.apache.org/jira/browse/HBASE-21915
             Project: HBase
          Issue Type: Bug
            Reporter: Josh Elser
            Assignee: Josh Elser


FileLinkInputStream is an InputStream which handles the indirection of where 
the real HFile lives. This implementation is wrapped via 
FSDataInputStreamWrapper and is transparent when it's being used by a caller. 
Often, we have an FSDataInputStreamWrapper wrapping a FileLinkInputStream which 
wraps an FSDataInputStream.

The problem is that FileLinkInputStream does not implement the \{{CanUnbuffer}} 
interface, which means that the underlying {{FSDataInputStream}} for the HFile 
the link refers to doesn't get {{unbuffer()}} called on it. This can cause an 
open Socket to hang around, as described in HBASE-9393.

Both [~wchevreuil] and myself have run into this, each for different users. We 
think the commonality as to why these users saw this (but we haven't run into 
it on our own) is that it requires a very large snapshot to be brought into a 
new system. Big kudos to [~esteban] for his help in diagnosing this as well!

If this analysis is accurate, it would affect all branches.

 



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