请教一个问题，我有一个flink cdc job，在session模式下一直报错？

请教一个问题，我有一个flink cdc job，在session模式下一直报错 Caused by: org.apache.flink.util.FlinkRuntimeException: java.sql.SQLTransientConnectionException: connection-pool-172.17.16.31:3306 - Connection is not available, request timed out after 30000ms. at com.ververica.cdc.connectors.mysql.source.connection.JdbcConnectionFactory.connect(JdbcConnectionFactory.java:72) at io.debezium.jdbc.JdbcConnection.connection(JdbcConnection.java:890) at io.debezium.jdbc.JdbcConnection.connection(JdbcConnection.java:885) at io.debezium.jdbc.JdbcConnection.connect(JdbcConnection.java:418) at com.ververica.cdc.connectors.mysql.debezium.DebeziumUtils.openJdbcConnection(DebeziumUtils.java:61) ... 14 more Caused by: java.sql.SQLTransientConnectionException: connection-pool-172.17.16.31:3306 - Connection is not available, request timed out after 30000ms. at com.ververica.cdc.connectors.shaded.com.zaxxer.hikari.pool.HikariPool.createTimeoutException(HikariPool.java:696) at com.ververica.cdc.connectors.shaded.com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:197) at com.ververica.cdc.connectors.shaded.com.zaxxer.hikari.pool.HikariPool.getConnection(HikariPool.java:162) at com.ververica.cdc.connectors.shaded.com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:100) at com.ververica.cdc.connectors.mysql.source.connection.JdbcConnectionFactory.connect(JdbcConnectionFactory.java:59) ... 18 more 但是使用yarn-per-job模式就没有问题，我试图在source里面加大connection.pool.size到30也没有用，我job本身的并行度只有3。请问有遇到过这个问题的吗，我的sql就是select出来就写入下游，也没有lookup join？