HMS may leak db connection when execute exchange partitions

In your production deployment, the Hive Thrift server is deployed. In the HMSHandler.exchange_partitions method, it executes RawStore.openTransaction and performs some checks. If these checks fail, an exception is thrown without executing commitTransaction or rollbackTransaction. This can result in a leakage of the underlying database connection, as it is not returned to the thread pool. Consequently, all threads may be blocked at the point of obtaining a connection from the connection pool.  

We should place all operations that come after RawStore.openTransaction inside a try-finally block.

reproduce statement:

ALTER TABLE dev.yyy EXCHANGE PARTITION (par='') WITH TABLE ods.xxx;