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From "Jingcheng Du (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13480) ShortCircuitConnection doesn't short-circuit all calls as expected
Date Wed, 12 Aug 2015 07:11:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14693043#comment-14693043
] 

Jingcheng Du commented on HBASE-13480:
--------------------------------------

bq. I'm wondering if Enis' suggestion of ConnectionAdapter extending ConnectionImplementation
instead is the less-error-prone approach
I think it's not necessary.
We need a ClusterConnection instance, not a ConnectionImplementation instance (what if there
is a new implementation of ClusterConnection?). If ConnectionAdapter has to be limited to
ConnectionImplementation. it's better to have the switch ( using local or remote instance)
directly in ConnectionImplementation instead?

> ShortCircuitConnection doesn't short-circuit all calls as expected
> ------------------------------------------------------------------
>
>                 Key: HBASE-13480
>                 URL: https://issues.apache.org/jira/browse/HBASE-13480
>             Project: HBase
>          Issue Type: Bug
>          Components: Client
>    Affects Versions: 1.0.0, 2.0.0, 1.1.0
>            Reporter: Josh Elser
>            Assignee: Josh Elser
>             Fix For: 2.0.0, 1.3.0, 1.2.1, 1.0.3, 1.1.3
>
>
> Noticed the following situation in debugging unexpected unit tests failures in HBASE-13351.
> {{ConnectionUtils#createShortCircuitHConnection(Connection, ServerName, AdminService.BlockingInterface,
ClientService.BlockingInterface)}} is intended to avoid the extra RPC by calling the server's
instantiation of the protobuf rpc stub directly for the AdminService and ClientService.
> The problem is that this is insufficient to actually avoid extra "remote" RPCs as all
other calls to the Connection are routed to a "real" Connection instance. As such, any object
created by the "real" Connection (such as an HTable) will use the real Connection, not the
SSC.
> The end result is that {{MasterRpcService#reportRegionStateTransition(RpcController,
ReportRegionStateTransitionRequest)}} will make additional "remote" RPCs over what it thinks
is an SSC through a {{Get}} on {{HTable}} which was constructed using the SSC, but the {{Get}}
itself will use the underlying real Connection instead of the SSC. With insufficiently sized
thread pools, this has been observed to result in RPC deadlock in the HMaster where an RPC
attempts to make another RPC but there are no more threads available to service the second
RPC so the first RPC blocks indefinitely.



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