SqlServerWriter error SQLServerException: The connection is closed

`2018-06-05 11:01:36.775 [job-0] INFO StandAloneJobContainerCommunicator - Total 2007552 records, 48661154 bytes | Speed 72.72KB/s, 3072 records/s | Error 0 records, 0 bytes | All Task WaitWriterTime 997.325s | All Task WaitReaderTime 2.974s | Percentage 0.00%
2018-06-05 11:01:46.776 [job-0] INFO StandAloneJobContainerCommunicator - Total 2028032 records, 49157692 bytes | Speed 48.49KB/s, 2048 records/s | Error 0 records, 0 bytes | All Task WaitWriterTime 1,005.132s | All Task WaitReaderTime 2.997s | Percentage 0.00%
2018-06-05 11:01:55.758 [0-0-0-writer] WARN CommonRdbmsWriter$Task - 回滚此次写入, 采用每次写入一行方式提交. 因为:Connection timed out (Write failed)
2018-06-05 11:01:55.762 [0-0-0-writer] ERROR WriterRunner - Writer Runner Received Exceptions:
com.alibaba.datax.common.exception.DataXException: Code:[DBUtilErrorCode-05], Description:[往您配置的写入表中写入数据时失败.]. - com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:190)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.checkClosed(SQLServerConnection.java:388)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.rollback(SQLServerConnection.java:1954)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.doBatchInsert(CommonRdbmsWriter.java:361)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWriteWithConnection(CommonRdbmsWriter.java:291)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWrite(CommonRdbmsWriter.java:319)
at com.alibaba.datax.plugin.writer.sqlserverwriter.SqlServerWriter$Task.startWrite(SqlServerWriter.java:81)
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56)
at java.lang.Thread.run(Thread.java:748)
- com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:190)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.checkClosed(SQLServerConnection.java:388)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.rollback(SQLServerConnection.java:1954)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.doBatchInsert(CommonRdbmsWriter.java:361)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWriteWithConnection(CommonRdbmsWriter.java:291)
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWrite(CommonRdbmsWriter.java:319)
at com.alibaba.datax.plugin.writer.sqlserverwriter.SqlServerWriter$Task.startWrite(SqlServerWriter.java:81)
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56)
at java.lang.Thread.run(Thread.java:748)

at com.alibaba.datax.common.exception.DataXException.asDataXException(DataXException.java:40) ~[datax-common-0.0.1-SNAPSHOT.jar:na]
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWriteWithConnection(CommonRdbmsWriter.java:302) ~[plugin-rdbms-util-0.0.1-SNAPSHOT.jar:na]
at com.alibaba.datax.plugin.rdbms.writer.CommonRdbmsWriter$Task.startWrite(CommonRdbmsWriter.java:319) ~[plugin-rdbms-util-0.0.1-SNAPSHOT.jar:na]
at com.alibaba.datax.plugin.writer.sqlserverwriter.SqlServerWriter$Task.startWrite(SqlServerWriter.java:81) ~[sqlserverwriter-0.0.1-SNAPSHOT.jar:na]
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56) ~[datax-core-0.0.1-SNAPSHOT.jar:na]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The connection is closed.
`
从mysql导出数据到sqlserver，连接超时，jdbcurl配置：
`"jdbcUrl": "jdbc:sqlserver://192.168.8.155;database=TKTemp;loginTimeout=20000"`
报错时程序仅运行了1000秒，远小于配置的超时时间20000秒。

Start with CommonRdbmsWriter.java at doBatchInsert and startWriteWithConnection, then inspect SqlServerWriter.java at Task.startWrite. Compare the SQL Server JDBC loginTimeout setting with the reported connection failure and trace how the closed connection is handled. Done means the timeout behavior and resulting error handling are understood and covered by an appropriate regression test.

Written by the indexing model from the issue text.