Zhen Wang

Hi @dongjoon-hyun , could you please help me review it?

> Why it is an issue particular for `InsertIntoHadoopFsRelationCommand`? `InsertIntoHiveTable` always uses hive staging dir https://github.com/apache/spark/blob/b0c831d3408dddfbbf3acacbe8100a9e08b400de/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala#L107 `InsertIntoHadoopFsRelationCommand` only uses spark staging dir in dynamic overwrite mode, otherwise it uses `table_location/_temporary`...

> The usecase looks suspicious to me. Is it a valid one? I'm not sure that `InsertIntoHadoopFsRelationCommand` guarantees concurrent writing to same table. It seems a reasonable requirement to concurrently...

I have made some modifications to get the lineage of spark SQL operation hive, which can be used as a reference, but I am not sure if there will be...

We might be able to remove the `synchronized` in the `FileSystemContext.closeContext` method and change the judgment to `if (!mClosed.getAndSet(true)) {`

cc @yaooqinn, is this reasonable?

> What's the problem you have met? I use kyuubi-ctl to delete kyuubi server but the process does not exit, and only KyuubiThriftBinaryFrontendServiceHandler-Pool is non-daemon. > do we still need...

> You mean after all connections are disconnected and the server `stop` being triggered? yea, but I don't know why that thread doesn't end.

full jstack info: ``` Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.131-b11 mixed mode): "Attach Listener" #3914947 daemon prio=9 os_prio=0 tid=0x00007f84e0001000 nid=0x11acfc waiting on condition [0x0000000000000000] java.lang.Thread.State: RUNNABLE "KyuubiThriftBinaryFrontendServiceHandler-Pool:...

It seems to be caused by kyuubi server having cleaned up the timeout session/operation but the client has not closed the connection.