zhmin

[metric] fix flink cdc metric conflict with flink built in metric

7

CurrentEmitEventTimeLag and currentFetchEventTimeLag metrics are both registered in flink cdc and flink framework.Flink MetricRegistryImpl is responsible for metric registering, when the metric with same name is registered twice, only the...

#### What type of PR is this? enhancements：reduce driver memory usage #### What this PR does / why we need it: When running large data task，spark driver offen encounters oom...

if clean timer duration is greater than ttl, data will remain more than ttl. so timer duration is set equal ttl

修复限速配置不规范，但是没有抛出异常

2

当使用限速的时候，需要指定core.transport.channel.speed的相关配置参数，否则应该抛出异常。 并且正确的使用限速文档，已经在introduction.md修改了