[GitHub] drill pull request #1094: DRILL-6090: While connecting to drill-bits using J...

[milindt]

GitHub user milindt opened a pull request:

    https://github.com/apache/drill/pull/1094

    DRILL-6090: While connecting to drill-bits using JDBC Driver through …

    …Zookeeper, a lot of "Curator-Framework-0" threads are created if 
connection to drill-bit is not successful(no drill-bits are up/reachable)
    
    I am using Drill JDBC driver 1.12.0 to connect to MapR-DB. I am finding the 
available drill-bits using Zookeepers. When drill-bits are not up or not 
reachable, the connection is failed with exception: "Failure in connecting to 
Drill: oadd.org.apache.drill.exec.rpc.RpcException: Failure setting up ZK for 
client", which is expected, but number of threads created by 
ZKClusterCoordinator just keeps on increasing.
    
    Steps to reproduce the issue
    
    Setup a connection with a drill-bit using Apache Drill JDBC driver 1.12.0 
through Zookeeper hosts(port 5181)
    Now stop the drill-bit services or block the drill-bit IPs using iptable 
rules
    Truncate catalina logs
    Try to connect to the drill-bit/hit a code path that requires connection to 
drill-bits.
    Take thread dump using kill -QUIT <java process id>
    grep -c "Curator-Framework-0" catalina.out
    Observe that the curator framework thread just keep on accumulating
    
    RCA:
    
    ZKClusterCoordinator creates curator threads in the constructor
    ZKClusterCoordinator is instantiated by DrillClient.connect
    DrillClient.connect is called in DrillConnectionImpl constructor
    
    Fix:
    
    Call DrillConnectionImpl .cleanup() from all the catch blocks in the 
DrillConnectionImpl  constructor.
    
    [JIRA link](https://issues.apache.org/jira/browse/DRILL-6090)
    
    If this fix is accepted, will there be a release from this branch(1.12.0)? 
A release with minor version may be.

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/milindt/drill 1.12.0

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/drill/pull/1094.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #1094
    
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