Fix issue when running multiple project containing IOU nodes on the same server. Ref #1239.

gns3server/compute/iou/__init__.py

@@ -25,6 +25,7 @@ import asyncio
 from ..base_manager import BaseManager
 from .iou_error import IOUError
 from .iou_vm import IOUVM
+from .utils.application_id import get_next_application_id
 
 import logging
 log = logging.getLogger(__name__)
@@ -38,8 +39,7 @@ class IOU(BaseManager):
     def __init__(self):
 
         super().__init__()
-        self._free_application_ids = list(range(1, 512))
-        self._used_application_ids = {}
+        self._iou_id_lock = asyncio.Lock()
 
     @asyncio.coroutine
     def create_node(self, *args, **kwargs):
@@ -49,40 +49,14 @@ class IOU(BaseManager):
         :returns: IOUVM instance
         """
 
-        node = yield from super().create_node(*args, **kwargs)
-        try:
-            self._used_application_ids[node.id] = self._free_application_ids.pop(0)
-        except IndexError:
-            raise IOUError("Cannot create a new IOU VM (limit of 512 VMs reached on this host)")
+        with (yield from self._iou_id_lock):
+            # wait for a node to be completely created before adding a new one
+            # this is important otherwise we allocate the same application ID
+            # when creating multiple IOU node at the same time
+            application_id = get_next_application_id(self.nodes)
+            node = yield from super().create_node(*args, application_id=application_id, **kwargs)
         return node
 
-    @asyncio.coroutine
-    def close_node(self, node_id, *args, **kwargs):
-        """
-        Closes an IOU VM.
-
-        :returns: IOUVM instance
-        """
-
-        node = self.get_node(node_id)
-        if node_id in self._used_application_ids:
-            i = self._used_application_ids[node_id]
-            self._free_application_ids.insert(0, i)
-            del self._used_application_ids[node_id]
-        yield from super().close_node(node_id, *args, **kwargs)
-        return node
-
-    def get_application_id(self, node_id):
-        """
-        Get an unique application identifier for IOU.
-
-        :param node_id: Node identifier
-
-        :returns: IOU application identifier
-        """
-
-        return self._used_application_ids.get(node_id, 1)
-
     @staticmethod
     def get_legacy_vm_workdir(legacy_vm_id, name):
         """