James Clampffer created HDFS-12103:
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Summary: libhdfs++: Provide workaround to support cancel on
filesystem connect until HDFS-11437 is resolved
Key: HDFS-12103
URL: https://issues.apache.org/jira/browse/HDFS-12103
Project: Hadoop HDFS
Issue Type: Sub-task
Reporter: James Clampffer
Assignee: James Clampffer
HDFS-11437 is going to take a non-trivial amount of work to do right. In the
meantime it'd be nice to have a way to cancel pending connections (even when
the FS claimed they are finished).
Proposed workaround is to relax the rules about when FileSystem::CancelPending
connect can be called since it isn't able to properly determine when it's
connected anyway. In order to determine when the FS has connected you can do
some simple RPC call since that will wait on failover. If CancelPending can be
called during that first RPC call then it will effectively be canceling
FileSystem::Connect
Current cancel rules - asterisk on steps where CancelPending is allowed
FileSystem::Connect called
FileSystem communicates with first NN *
FileSystem::Connect returns - even if it hasn't communicated with the active NN
Proposed relaxation
FileSystem::Connect called
FileSystem communicates with first NN*
FileSystem::Connect returns *
FileSystem::GetFileInfo called * -any namenode RPC call will do, ignore perm
errors
RPC engine blocks until it hits the active or runs out of retries *
FileSystem::GetFileInfo returns
It'd be up to the user to add in the dummy NN RPC call. Once HDFS-11437 is
fixed this workaround can be removed.
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