Grpc upgrade: prevent from reusing same port too soon after server shutdown (#1111)

Author: cbellot000

src/ansys/dpf/core/server.py

@@ -121,7 +121,6 @@ def shutdown_all_session_servers():
             print(e.args)
             pass
     shutdown_global_server()
-    _server_instances.clear()
 
 
 def start_local_server(

src/ansys/dpf/core/server_types.py

@@ -202,6 +202,7 @@ def launch_dpf(ansys_path, ip=LOCALHOST, port=DPF_DEFAULT_PORT, timeout=10):
     _wait_and_check_server_connection(
         process, port, timeout, lines, current_errors, stderr=None, stdout=None
     )
+    return process
 
 
 def launch_dpf_on_docker(
@@ -368,6 +369,33 @@ def check_ansys_grpc_dpf_version(server, timeout):
         )
 
 
+class GhostServer:
+    ip: str
+    _port: int
+    close_time: float
+
+    def __init__(self, ip: str, port: int, close_time: float = None):
+        """
+        Internal class used to keep in memory the port used by previous servers.
+        Adds a timeout before reusing ports of shutdown servers.
+        """
+        self.ip = ip
+        self._port = port
+        self.closed_time = close_time
+        if self.closed_time is None:
+            self.closed_time = time.time()
+
+    @property
+    def port(self) -> int:
+        """Returns the port of shutdown server if the shutdown happened less than 10s ago."""
+        if time.time() - self.closed_time > 10:
+            return -1
+        return self._port
+
+    def __call__(self, *args, **kwargs):
+        return self
+
+
 class BaseServer(abc.ABC):
     """Abstract class for servers"""
 
@@ -599,7 +627,14 @@ def __del__(self):
             if hasattr(core, "_server_instances") and core._server_instances is not None:
                 for i, server in enumerate(core._server_instances):
                     if server() == self:
-                        core._server_instances.remove(server)
+                        if hasattr(self, "_input_ip") and hasattr(self, "_input_port"):
+                            # keeps a ghost instance with the used port and ip to prevent
+                            # from reusing the port to soon after shutting down: bug
+                            core._server_instances[i] = GhostServer(
+                                self._input_ip, self._input_port
+                            )
+                        else:
+                            core._server_instances.remove(server)
         except:
             warnings.warn(traceback.format_exc())
 
@@ -699,7 +734,6 @@ def __init__(
                 self._local_server = True
 
         self._client = GrpcClient(address)
-
         # store port and ip for later reference
         self._address = address
         self._input_ip = ip

tests/entry/test_entry.py

@@ -83,8 +83,11 @@ def test_apply_context_remote(remote_config_server_type):
     op.connect(0, field)
     op.connect(1, 0.0)
     op.eval()
+    field = None
     assert dpf.SERVER.context == dpf.AvailableServerContexts.premium
     dpf.server.shutdown_all_session_servers()
+    field = dpf.Field()
+    field.append([0.0], 1)
     if conftest.SERVERS_VERSION_GREATER_THAN_OR_EQUAL_TO_6_1:
         with pytest.raises(errors.DPFServerException):
             op = dpf.Operator("core::field::high_pass")