tangshangwen created FLINK-16708:
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             Summary: When a JDBC connection has been closed, the retry policy 
of the JDBCUpsertOutputFormat cannot take effect and may result in data loss
                 Key: FLINK-16708
                 URL: https://issues.apache.org/jira/browse/FLINK-16708
             Project: Flink
          Issue Type: Bug
          Components: Connectors / JDBC
    Affects Versions: 1.10.0
            Reporter: tangshangwen


In our test environment, I used the tcpkill command to simulate a scenario 
where the postgresql connection was closed. I found that the retry strategy of 
the flush method did not take effect, and when it retried the second time, it 
could not recognize that the connection had been closed because Before the 
first check whether the connection is closed, the batchStatements of 
PgStatement have been cleared, which causes the second execution to check that 
the batchStatements are empty and return normally.
{code:java}
2020-03-20 21:16:18.246 [jdbc-upsert-output-format-thread-1] ERROR 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat  - JDBC executeBatch 
error, retry times = 1
 org.postgresql.util.PSQLException: This connection has been closed.
         at org.postgresql.jdbc.PgConnection.checkClosed(PgConnection.java:857)
         at 
org.postgresql.jdbc.PgConnection.getAutoCommit(PgConnection.java:817)
         at 
org.postgresql.jdbc.PgStatement.internalExecuteBatch(PgStatement.java:813)
         at org.postgresql.jdbc.PgStatement.executeBatch(PgStatement.java:873)
         at 
org.postgresql.jdbc.PgPreparedStatement.executeBatch(PgPreparedStatement.java:1569)
         at 
org.apache.flink.api.java.io.jdbc.writer.AppendOnlyWriter.executeBatch(AppendOnlyWriter.java:62)
         at 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat.flush(JDBCUpsertOutputFormat.java:159)
         at 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat.lambda$open$0(JDBCUpsertOutputFormat.java:124)
         at 
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
         at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
         at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
         at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
         at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
         at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
         at java.lang.Thread.run(Thread.java:748)
 2020-03-20 21:16:21.247 [jdbc-upsert-output-format-thread-1] ERROR 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat  - JDBC executeBatch 
error, retry times = 1
 org.postgresql.util.PSQLException: This connection has been closed.
         at org.postgresql.jdbc.PgConnection.checkClosed(PgConnection.java:857)
         at 
org.postgresql.jdbc.PgConnection.getAutoCommit(PgConnection.java:817)
         at 
org.postgresql.jdbc.PgStatement.internalExecuteBatch(PgStatement.java:813)
         at org.postgresql.jdbc.PgStatement.executeBatch(PgStatement.java:873)
         at 
org.postgresql.jdbc.PgPreparedStatement.executeBatch(PgPreparedStatement.java:1569)
         at 
org.apache.flink.api.java.io.jdbc.writer.AppendOnlyWriter.executeBatch(AppendOnlyWriter.java:62)
         at 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat.flush(JDBCUpsertOutputFormat.java:159)
         at 
org.apache.flink.api.java.io.jdbc.JDBCUpsertOutputFormat.lambda$open$0(JDBCUpsertOutputFormat.java:124)
         at 
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
         at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
         at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
         at 
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
         at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
         at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
         at java.lang.Thread.run(Thread.java:748)
{code}



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