[bugfix] Fix crash of local scheduler with flexible allocation

reframe/core/schedulers/__init__.py

@@ -334,3 +334,9 @@ def finished(self):
             raise JobNotStartedError('cannot poll an unstarted job')
 
         return self.scheduler.finished(self)
+
+
+class Node(abc.ABC):
+    @abc.abstractmethod
+    def is_available(self):
+        '''Return ``True`` if this node is available, ``False`` otherwise.'''

reframe/core/schedulers/local.py

@@ -56,10 +56,10 @@ def emit_preamble(self, job):
         return []
 
     def allnodes(self):
-        return [socket.gethostname()]
+        return [_LocalNode(socket.gethostname())]
 
     def filternodes(self, job, nodes):
-        return [socket.gethostname()]
+        return [_LocalNode(socket.gethostname())]
 
     def _kill_all(self, job):
         '''Send SIGKILL to all the processes of the spawned job.'''
@@ -169,3 +169,11 @@ def finished(self, job):
             return False
 
         return True
+
+
+class _LocalNode(sched.Node):
+    def __init__(self, name):
+        self._name = name
+
+    def is_available(self):
+        return True

reframe/core/schedulers/slurm.py

@@ -166,7 +166,7 @@ def allnodes(self):
             raise JobError('could not retrieve node information') from e
 
         node_descriptions = completed.stdout.splitlines()
-        return create_nodes(node_descriptions)
+        return _create_nodes(node_descriptions)
 
     def _get_default_partition(self):
         completed = _run_strict('scontrol -a show -o partitions')
@@ -272,13 +272,13 @@ def _get_reservation_nodes(self, reservation):
 
         completed = _run_strict('scontrol -a show -o %s' % reservation_nodes)
         node_descriptions = completed.stdout.splitlines()
-        return create_nodes(node_descriptions)
+        return _create_nodes(node_descriptions)
 
     def _get_nodes_by_name(self, nodespec):
         completed = os_ext.run_command('scontrol -a show -o node %s' %
                                        nodespec)
         node_descriptions = completed.stdout.splitlines()
-        return create_nodes(node_descriptions)
+        return _create_nodes(node_descriptions)
 
     def _set_nodelist(self, job, nodespec):
         if job.nodelist is not None:
@@ -485,16 +485,16 @@ def cancel(self, job):
         self._cancelled = True
 
 
-def create_nodes(descriptions):
+def _create_nodes(descriptions):
     nodes = set()
     for descr in descriptions:
         with suppress(JobError):
-            nodes.add(SlurmNode(descr))
+            nodes.add(_SlurmNode(descr))
 
     return nodes
 
 
-class SlurmNode:
+class _SlurmNode(sched.Node):
     '''Class representing a Slurm node.'''
 
     def __init__(self, node_descr):

unittests/test_schedulers.py

@@ -16,7 +16,7 @@
 from reframe.core.launchers.registry import getlauncher
 from reframe.core.schedulers import Job
 from reframe.core.schedulers.registry import getscheduler
-from reframe.core.schedulers.slurm import SlurmNode, create_nodes
+from reframe.core.schedulers.slurm import _SlurmNode, _create_nodes
 
 
 class _TestJob(abc.ABC):
@@ -304,8 +304,14 @@ def test_cancel_term_ignore(self):
         self.assertProcessDied(sleep_pid)
 
     def test_guess_num_tasks(self):
+        # We want to trigger bug #1087 (Github), that's we set allocation
+        # policy to idle.
         self.testjob.num_tasks = 0
-        assert self.testjob.guess_num_tasks() == 1
+        self.testjob._sched_flex_alloc_nodes = 'idle'
+        self.prepare()
+        self.testjob.submit()
+        self.testjob.wait()
+        assert self.testjob.num_tasks == 1
 
 
 class TestSlurmJob(_TestJob, unittest.TestCase):
@@ -611,7 +617,7 @@ def create_dummy_nodes(obj):
 
                              'Node invalid_node2 not found']
 
-        return create_nodes(node_descriptions)
+        return _create_nodes(node_descriptions)
 
     def create_reservation_nodes(self, res):
         return {n for n in self.testjob.scheduler.allnodes()
@@ -906,15 +912,15 @@ def setUp(self):
             'failed [reframe_user@01 Jan 2018]'
         )
 
-        self.allocated_node = SlurmNode(allocated_node_description)
-        self.allocated_node_copy = SlurmNode(allocated_node_description)
-        self.idle_node = SlurmNode(idle_node_description)
-        self.idle_drained = SlurmNode(idle_drained_node_description)
-        self.no_partition_node = SlurmNode(no_partition_node_description)
+        self.allocated_node = _SlurmNode(allocated_node_description)
+        self.allocated_node_copy = _SlurmNode(allocated_node_description)
+        self.idle_node = _SlurmNode(idle_node_description)
+        self.idle_drained = _SlurmNode(idle_drained_node_description)
+        self.no_partition_node = _SlurmNode(no_partition_node_description)
 
     def test_no_node_name(self):
         with self.assertRaises(JobError):
-            SlurmNode(self.no_name_node_description)
+            _SlurmNode(self.no_name_node_description)
 
     def test_states(self):
         self.assertEqual(self.allocated_node.states, {'ALLOCATED'})