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https://issues.apache.org/jira/browse/HDDS-17448?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated HDDS-17448:
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Labels: pull-request-available (was: )
> gRPC OM client should retry a not-ready leader like the Hadoop RPC client
> -------------------------------------------------------------------------
>
> Key: HDDS-17448
> URL: https://issues.apache.org/jira/browse/HDDS-17448
> Project: Apache Ozone
> Issue Type: Sub-task
> Reporter: Chu Cheng Li
> Assignee: Chu Cheng Li
> Priority: Major
> Labels: pull-request-available
>
> h3. Problem
> * The OM retry policy retries a not-ready leader on the same OM, after a
> wait. It does this only for a {{ServiceException}}.
> {{GrpcOmTransport#unwrapException}} returns the OM exception itself. Thus, on
> {{OMLeaderNotReadyException}}, the gRPC client fails over to the next OM with
> no wait.
> * {{GrpcOmTransport}} retries only the leader path. The follower read loop in
> {{GrpcOMFollowerReadFailoverProxyProvider}} has no retry around it. Thus, on
> {{OMLeaderNotReadyException}}, the loop falls back to the leader path and
> sends a new request at once.
> * The Hadoop RPC client does not have these problems. Its {{RetryProxy}}
> wraps the follower read and the leader path, and it gives the retry policy a
> {{ServiceException}}.
> h3. Changes
> * {{GrpcOmTransport}}: move the retry loop from {{submitRequestToLeader}} to
> {{submitRequest}}, around the follower read and the leader path. Give the
> retry policy a {{ServiceException}} with the {{RemoteException}} cause.
> * {{GrpcOMFollowerReadFailoverProxyProvider}}: throw
> {{OMLeaderNotReadyException}} to the retry loop, as
> {{HadoopRpcOMFollowerReadFailoverProxyProvider}} does.
> h3. Tests
> * The gRPC client retries a not-ready leader on the same OM, after a wait.
> * A follower read that gets {{OMLeaderNotReadyException}} goes through the
> same retry.
> Found in the review of HDDS-16737:
> https://github.com/apache/ozone/pull/11418#discussion_r4369504955
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