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https://issues.apache.org/jira/browse/SPARK-56019?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-56019:
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Labels: pull-request-available (was: )
> Close JDBC connection on task kill to unblock native socket reads
> -----------------------------------------------------------------
>
> Key: SPARK-56019
> URL: https://issues.apache.org/jira/browse/SPARK-56019
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 4.2.0
> Reporter: Ivan Sadikov
> Priority: Major
> Labels: pull-request-available
>
> *Problem:* **When a Spark task is killed via the task reaper, tasks that are
> blocked in a native JDBC socket read (e.g.
> java.net.SocketInputStream.socketRead0() or
> sun.nio.ch.SocketDispatcher.read0()) never terminate. This affects both the
> read path (JDBCRDD.compute — blocked in ResultSet.next()) and the write path
> (JdbcUtils.savePartition — blocked in PreparedStatement.executeBatch()).
> *Root* *Cause:* **The SQL Server JDBC driver (and others) perform I/O via
> blocking native calls. Thread.interrupt() sets the interrupt flag but does
> *not* unblock a thread stuck in a native socket read. The existing
> addTaskCompletionListener that closes rs/stmt/conn fires only _after_ the
> task body exits — which never happens if the thread is stuck waiting for the
> database.
> *Potential* *Fix:* **Register a mechanism that fires from the task-killer
> side (before the task thread exits) to forcibly close the JDBC Connection.
> Closing the connection closes the underlying TCP socket, which causes the
> blocked native read to throw a SocketException (propagated as SQLException),
> promptly unblocking the task thread. We will need to handle
> * Write path (JdbcUtils.savePartition)
> * Read path (JDBCRDD.compute)
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