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https://issues.apache.org/jira/browse/KAFKA-4371?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15632717#comment-15632717
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Sagar Rao commented on KAFKA-4371:
----------------------------------
Another thing to note is that we get this exception when I try to delete an
existing connector. After that we get a CommunicationLinkException and then all
the processes stop. Not sure how is this connected though.
> Sporadic ConnectException shuts down the whole connect process
> --------------------------------------------------------------
>
> Key: KAFKA-4371
> URL: https://issues.apache.org/jira/browse/KAFKA-4371
> Project: Kafka
> Issue Type: Bug
> Reporter: Sagar Rao
> Priority: Critical
>
> I had setup a 2 node distributed kafka-connect process. Everything went well
> and I could see lot of data flowing into the relevant kafka topics.
> After some time, JDBCUtils.getCurrentTimeOnDB threw a ConnectException with
> the following stacktrace:
> The last packet successfully received from the server was 792 milliseconds
> ago. The last packet sent successfully to the server was 286 milliseconds
> ago. (io.confluent.connect.jdbc.source.JdbcSourceTask:234)
> [2016-11-02 12:42:06,116] ERROR Failed to get current time from DB using
> query select CURRENT_TIMESTAMP; on database MySQL
> (io.confluent.connect.jdbc.util.JdbcUtils:226)
> com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link
> failure
> The last packet successfully received from the server was 1,855 milliseconds
> ago. The last packet sent successfully to the server was 557 milliseconds
> ago.
> at sun.reflect.GeneratedConstructorAccessor51.newInstance(Unknown
> Source)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
> at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
> at
> com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1117)
> at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3829)
> at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2449)
> at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2629)
> at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2719)
> at
> com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
> at
> com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1379)
> at
> com.mysql.jdbc.StatementImpl.createResultSetUsingServerFetch(StatementImpl.java:651)
> at com.mysql.jdbc.StatementImpl.executeQuery(StatementImpl.java:1527)
> at
> io.confluent.connect.jdbc.util.JdbcUtils.getCurrentTimeOnDB(JdbcUtils.java:220)
> at
> io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier.executeQuery(TimestampIncrementingTableQuerier.java:157)
> at
> io.confluent.connect.jdbc.source.TableQuerier.maybeStartQuery(TableQuerier.java:78)
> at
> io.confluent.connect.jdbc.source.TimestampIncrementingTableQuerier.maybeStartQuery(TimestampIncrementingTableQuerier.java:57)
> at
> io.confluent.connect.jdbc.source.JdbcSourceTask.poll(JdbcSourceTask.java:207)
> at
> org.apache.kafka.connect.runtime.WorkerSourceTask.execute(WorkerSourceTask.java:155)
> at
> org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:140)
> at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:175)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.net.SocketException: Broken pipe (Write failed)
> at java.net.SocketOutputStream.socketWrite0(Native Method)
> at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
> at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
> at
> java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
> at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
> at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3810)
> ... 20 more
> This was just a minor glitch to the connection as the ec2 isntances are able
> to connect to the Mysql Aurora instances without any issues.
> But, after this exception(which is there a number of times), none of the
> connectors' tasks are executing. Beyond this, all I see in the logs is
> [2016-11-02 16:17:41,983] ERROR Failed to run query for table
> TimestampIncrementingTableQuerier{name='eng_match_series', query='null',
> topicPrefix='ci-eng-', timestampColumn='modified', incrementingColumn='id'}:
> com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No
> operations allowed after statement closed.
> (io.confluent.connect.jdbc.source.JdbcSourceTask:234)
> Is this expected behaviour? I restarted the connector using REST apis but
> that didn't help. How do we handle such scenarios?
> Eventually I had to delete the connector and restart.
> The kafka version I am using is 0.10.0.1-cp1 as there were some custom
> changes we needed to make at the Connect level.
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