Fixed bug with intermittent hang on some versions of Oracle Database when

using asyncio and the database raises an error and output variables are
present (#278).

Author: anthony-tuininga

doc/src/release_notes.rst

@@ -15,6 +15,10 @@ Thin Mode Changes
 
 #)  Added support for using alternative event loop implementations like uvloop
     (`issue 276 <https://github.com/oracle/python-oracledb/issues/276>`__).
+#)  Fixed bug with intermittent hang on some versions of Oracle Database when
+    using asyncio and the database raises an error and output variables are
+    present
+    (`issue 278 <https://github.com/oracle/python-oracledb/issues/278>`__).
 #)  Fixed bug when fetch variables contain output converters and a query is
     re-executed
     (`issue 271 <https://github.com/oracle/python-oracledb/issues/271>`__).

src/oracledb/impl/thin/protocol.pyx

@@ -456,9 +456,6 @@ cdef class Protocol(BaseProtocol):
     cdef int _reset(self, Message message) except -1:
         cdef uint8_t marker_type, packet_type
 
-        # send reset marker
-        self._send_marker(self._write_buf, TNS_MARKER_TYPE_RESET)
-
         # read and discard all packets until a marker packet is received
         while True:
             packet_type = self._read_buf._current_packet.packet_type
@@ -469,11 +466,12 @@ cdef class Protocol(BaseProtocol):
                     break
             self._read_buf.wait_for_packets_sync()
 
-        # read error packet; first skip as many marker packets as may be sent
-        # by the server; if the server doesn't handle out-of-band breaks
-        # properly, some quit immediately and others send multiple reset
-        # markers (this addresses both situations without resulting in strange
-        # errors)
+        # send reset marker and then read error packet; first skip as many
+        # marker packets as may be sent by the server; if the server doesn't
+        # handle out-of-band breaks properly, some quit immediately and others
+        # send multiple reset markers (this addresses both situations without
+        # resulting in strange errors)
+        self._send_marker(self._write_buf, TNS_MARKER_TYPE_RESET)
         while packet_type == TNS_PACKET_TYPE_MARKER:
             self._read_buf.wait_for_packets_sync()
             packet_type = self._read_buf._current_packet.packet_type
@@ -851,9 +849,6 @@ cdef class BaseAsyncProtocol(BaseProtocol):
     async def _reset(self):
         cdef uint8_t marker_type, packet_type
 
-        # send reset marker
-        self._send_marker(self._write_buf, TNS_MARKER_TYPE_RESET)
-
         # read and discard all packets until a marker packet is received
         while True:
             packet_type = self._read_buf._current_packet.packet_type
@@ -864,11 +859,13 @@ cdef class BaseAsyncProtocol(BaseProtocol):
                     break
             await self._read_buf.wait_for_packets_async()
 
-        # read error packet; first skip as many marker packets as may be sent
-        # by the server; if the server doesn't handle out-of-band breaks
-        # properly, some quit immediately and others send multiple reset
-        # markers (this addresses both situations without resulting in strange
-        # errors)
+
+        # send reset marker and then read error packet; first skip as many
+        # marker packets as may be sent by the server; if the server doesn't
+        # handle out-of-band breaks properly, some quit immediately and others
+        # send multiple reset markers (this addresses both situations without
+        # resulting in strange errors)
+        self._send_marker(self._write_buf, TNS_MARKER_TYPE_RESET)
         while packet_type == TNS_PACKET_TYPE_MARKER:
             await self._read_buf.wait_for_packets_async()
             packet_type = self._read_buf._current_packet.packet_type