Hi Hequn, Establishing a connection for each batch write may also have idle connection problem, since we are not sure when the connection will be closed. We call flush() method when a batch is finished or snapshot state, but what if the snapshot is not enabled and the batch size not reached before the connection is closed?
May be we could use a Timer to test the connection periodically and keep it alive. What do you think? I will open a jira and try to work on that issue. Best, wangsan > On Jul 10, 2018, at 8:38 PM, Hequn Cheng <chenghe...@gmail.com> wrote: > > Hi wangsan, > > I agree with you. It would be kind of you to open a jira to check the problem. > > For the first problem, I think we need to establish connection each time > execute batch write. And, it is better to get the connection from a > connection pool. > For the second problem, to avoid multithread problem, I think we should > synchronized the batch object in flush() method. > > What do you think? > > Best, Hequn > > > > On Tue, Jul 10, 2018 at 2:36 PM, wangsan <wamg...@163.com > <mailto:wamg...@163.com>> wrote: > Hi all， > > I'm going to use JDBCAppendTableSink and JDBCOutputFormat in my Flink > application. But I am confused with the implementation of JDBCOutputFormat. > > 1. The Connection was established when JDBCOutputFormat is opened, and will > be used all the time. But if this connction lies idle for a long time, the > database will force close the connetion, thus errors may occur. > 2. The flush() method is called when batchCount exceeds the threshold, but it > is also called while snapshotting state. So two threads may modify upload and > batchCount, but without synchronization. > > Please correct me if I am wrong. > > —— > wangsan >
