[IMPALA-1227] HS2 shell ^C sometimes closes the session rather than canceling the query

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Bug
• Affects Version/s: Impala 2.0
• Component/s: Clients
• Labels: impala-shell shell
• Environment: cherry-pick f93ffd113fbeb624d08cb986a0ed3842ce1440bb from; http://gerrit.sjc.cloudera.com:8080/#/c/4062/; to get HS2 shell change
• Target Version: Product Backlog
• Assignee: Ishaan Joshi
• Reporter: Daniel Hecht
• Created: 11/Sep/14 20:17
• Updated: 22/Jan/16 02:47
• Resolved: 22/Jan/16 02:47

Description

In Abdullah's HS2 shell patch, the ^C signal handler intends to cancel the active query:

  def __signal_handler(self, signal, frame):
    if not self.cursor._last_operation_active:
      return
    # Create a new connection to the impalad and cancel the query.
    try:
      # self.query_handle_closed = True
      print_to_stderr(ImpalaShell.CANCELLATION_MESSAGE)
      cursor = self.imp_conn.cursor(session_handle=self.cursor.session_handle)
      cursor._last_operation_active = self.cursor._last_operation_active
      cursor._last_operation_handle = self.cursor._last_operation_handle
      cursor._last_operation_string = self.cursor._last_operation_string
      cursor.cancel_operation()
      self.cursor._last_operation_active = False
      self._validate_database()
    except Exception, e:
      print_to_stderr("Failed to reconnect and close: %s" % str(e))
      # TODO: Add a retry here

However, IMPALA-1178 shows that sometimes the shell is closing the session in response to ^C. It seems to happen if you press ^C immediately after issuing the query. If you wait a second and press ^C, then the query is cancelled correctly.

localhost:21050] > select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey;
Query: select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey
<immediately press ctrl+C>
^CSession closed
[localhost:21050] > select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey;
Query: select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey
Invalid session id
[localhost:21050] > connect;
Connected to localhost:21050
Server version: Hive Server 2
[localhost:21050] > select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey;
Query: select * from tpch.lineitem x, tpch.lineitem y where x.l_orderkey=y.l_orderkey
<wait one second then press ctrl+C>
^C Cancelling Query