关于 Tdengine 同步 Tdengine 的问题

使用 tdengine 同步时，需要在机器上安装 libtaos.so，如果同步配置采用 td-reader 写到 td-writer 中，会加载同一个本地类库，报错如下：
`经DataX智能分析,该任务最可能的错误原因是:
com.alibaba.datax.common.exception.DataXException: Code:[Framework-13], Description:[DataX插件运行时出错, 具体原因请参看DataX运行结束时的错误诊断信息 .]. - java.lang.UnsatisfiedLinkError: Native Library /usr/local/taos/driver/libtaos.so.2.4.0.30 already loaded in another classloader
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1900)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1850)
at java.lang.Runtime.loadLibrary0(Runtime.java:871)
at java.lang.System.loadLibrary(System.java:1124)
at com.taosdata.jdbc.TSDBJNIConnector.(TSDBJNIConnector.java:28)
at com.taosdata.jdbc.TSDBDriver.connect(TSDBDriver.java:130)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.alibaba.datax.plugin.writer.tdenginewriter.DefaultDataHandler.handle(DefaultDataHandler.java:75)
at com.alibaba.datax.plugin.writer.tdenginewriter.TDengineWriter$Task.startWrite(TDengineWriter.java:109)
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56)
at java.lang.Thread.run(Thread.java:750)
- java.lang.UnsatisfiedLinkError: Native Library /usr/local/taos/driver/libtaos.so.2.4.0.30 already loaded in another classloader
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1900)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1850)
at java.lang.Runtime.loadLibrary0(Runtime.java:871)
at java.lang.System.loadLibrary(System.java:1124)
at com.taosdata.jdbc.TSDBJNIConnector.(TSDBJNIConnector.java:28)
at com.taosdata.jdbc.TSDBDriver.connect(TSDBDriver.java:130)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.alibaba.datax.plugin.writer.tdenginewriter.DefaultDataHandler.handle(DefaultDataHandler.java:75)
at com.alibaba.datax.plugin.writer.tdenginewriter.TDengineWriter$Task.startWrite(TDengineWriter.java:109)
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56)
at java.lang.Thread.run(Thread.java:750)

at com.alibaba.datax.common.exception.DataXException.asDataXException(DataXException.java:40)
at com.alibaba.datax.core.job.scheduler.processinner.ProcessInnerScheduler.dealFailedStat(ProcessInnerScheduler.java:39)
at com.alibaba.datax.core.job.scheduler.AbstractScheduler.schedule(AbstractScheduler.java:99)
at com.alibaba.datax.core.job.JobContainer.schedule(JobContainer.java:534)
at com.alibaba.datax.core.job.JobContainer.start(JobContainer.java:119)
at com.alibaba.datax.core.Engine.start(Engine.java:92)
at com.alibaba.datax.core.Engine.entry(Engine.java:171)
at com.alibaba.datax.core.Engine.main(Engine.java:204)
Caused by: java.lang.UnsatisfiedLinkError: Native Library /usr/local/taos/driver/libtaos.so.2.4.0.30 already loaded in another classloader
at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1900)
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1850)
at java.lang.Runtime.loadLibrary0(Runtime.java:871)
at java.lang.System.loadLibrary(System.java:1124)
at com.taosdata.jdbc.TSDBJNIConnector.(TSDBJNIConnector.java:28)
at com.taosdata.jdbc.TSDBDriver.connect(TSDBDriver.java:130)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at com.alibaba.datax.plugin.writer.tdenginewriter.DefaultDataHandler.handle(DefaultDataHandler.java:75)
at com.alibaba.datax.plugin.writer.tdenginewriter.TDengineWriter$Task.startWrite(TDengineWriter.java:109)
at com.alibaba.datax.core.taskgroup.runner.WriterRunner.run(WriterRunner.java:56)
at java.lang.Thread.run(Thread.java:750)`

job 配置如下：
`{
"job": {
"content": [{
"reader": {
"name": "tdenginereader",
"parameter": {
"username": "root",
"password": "taosdata",
"connection": [
{
"querySql": [
"select * from power.d1001"
],
"jdbcUrl": [
"jdbc:TAOS://bigdata7:6030?timestampFormat=TIMESTAMP"
]
}
]
}
},
"writer": {
"name": "tdenginewriter",
"parameter": {
"username": "root",
"password": "taosdata",
"column": [
"ts",
"c",
"v",
"p"
],
"connection": [
{
"table": [
"meters1"
],
"jdbcUrl": "jdbc:TAOS://bigdata7:6030/power1"
}
],
"batchSize": 100,
"ignoreTagsUnmatched": true
}
}
}],
"setting": {
"speed": {
"channel": 1
}
}
}
}`

请问需要怎么配置 libtaos.so 才能让它只加载一次？

Start with the tdenginereader and tdenginewriter plugins, then trace the JDBC initialization at com.taosdata.jdbc.TSDBJNIConnector and the calls from DefaultDataHandler.handle and TDengineWriter$Task.startWrite. Reproduce the supplied job and verify the reader and writer can use TDengine without the libtaos.so classloader error; the issue is done when that configuration runs successfully.

Written by the indexing model from the issue text.