Communications link failure

datax编译后进行mysql到mysql的数据同步测试，报这个错误：

2022-01-12 13:28:51.723 [job-0] WARN DBUtil - test connection of [jdbc:mysql://localhost:3306/source_datax] failed, for Code:[MYSQLErrCode-02], Description:[数据库服务的IP地址或者Port错误，请检查填写的IP地址和Port或者联系DBA确认IP地址和Port是否正确。如果是同步中心用户请联系DBA确认idb上录入的IP和PORT信息和数据库的当前实际信息是一致的]. - 具体错误信息为：com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

非编译的datax进行数据时不会报这个错误

The report only provides a CommunicationsException log for a compiled DataX build and contrasts it with a non-compiled build; it names no source files or tests. Start by reproducing the MySQL-to-MySQL synchronization with both builds and compare their connection configuration and runtime behavior. Done means identifying the compiled-build difference that causes the connection failure and confirming a successful synchronization.

Written by the indexing model from the issue text.