Todd Lipcon created HDFS-3876:
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Summary: NN should not RPC to self to find trash defaults (causes
deadlock)
Key: HDFS-3876
URL: https://issues.apache.org/jira/browse/HDFS-3876
Project: Hadoop HDFS
Issue Type: Bug
Components: name-node
Affects Versions: 3.0.0, 2.2.0-alpha
Reporter: Todd Lipcon
Priority: Blocker
When transitioning a SBN to active, I ran into the following situation:
- the TrashPolicy first gets loaded by an IPC Server Handler thread. The
{{initialize}} function then tries to make an RPC to the same node to find out
the defaults.
- This is happening inside the NN write lock (since it's part of the active
initialization). Hence, all of the other handler threads are already blocked
waiting to get the NN lock.
- Since no handler threads are free, the RPC blocks forever and the NN never
enters active state.
We need to have a general policy that the NN should never make RPCs to itself
for any reason, due to potential for deadlocks like this.
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