Details
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Bug
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Status: Resolved
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Major
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Resolution: Not A Problem
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None
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None
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None
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Java SE 1.6.0-b105 on Linux 2.6.x
Description
We recently noticed a number of datanodes got stuck. The main thread that sends heartbeats and block reports is blocked in select() in side blockReport() RPC. I will add a stack trace in the next comment.
I am not sure why select was blocked forever since there is no connection open to NameNode. In fact, NN was restarted in between. It could be some JDK bug or a Hadoop bug.