Milind Takawale created DRILL-6090:
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Summary: 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)
Key: DRILL-6090
URL: https://issues.apache.org/jira/browse/DRILL-6090
Project: Apache Drill
Issue Type: Bug
Components: Client - JDBC
Affects Versions: 1.12.0
Environment: Centos 65, Java 7, Drill JDBC 1.12.0
Reporter: Milind Takawale
Fix For: 1.12.0
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.
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