Do a better job parallelizing the inital batch of tests when the

number of nodes is more than half the number of tests. This makes it
possible, for example, to run all tests in parallel, where previous
the maximum parallelization was half of all tests.

testing/test_dsession.py

@@ -27,6 +27,7 @@ class MockNode:
     def __init__(self):
         self.sent = []
         self.gateway = MockGateway()
+        self._shutdown = False
 
     def send_runtest_some(self, indices):
         self.sent.extend(indices)
@@ -37,6 +38,10 @@ class MockNode:
     def shutdown(self):
         self._shutdown = True
 
+    @property
+    def shutting_down(self):
+        return self._shutdown
+
 
 def dumpqueue(queue):
     while queue.qsize():
@@ -100,16 +105,15 @@ class TestLoadScheduling:
         assert sched.node2collection[node2] == collection
         sched.init_distribute()
         assert not sched.pending
-        assert not sched.tests_finished()
-        assert len(node1.sent) == 2
-        assert len(node2.sent) == 0
-        assert node1.sent == [0, 1]
+        assert sched.tests_finished()
+        assert len(node1.sent) == 1
+        assert len(node2.sent) == 1
+        assert node1.sent == [0]
+        assert node2.sent == [1]
         sched.remove_item(node1, node1.sent[0])
         assert sched.tests_finished()
-        sched.remove_item(node1, node1.sent[1])
-        assert sched.tests_finished()
 
-    def test_init_distribute_chunksize(self):
+    def test_init_distribute_batch_size(self):
         sched = LoadScheduling(2)
         sched.addnode(MockNode())
         sched.addnode(MockNode())
@@ -121,18 +125,56 @@ class TestLoadScheduling:
         # assert not sched.tests_finished()
         sent1 = node1.sent
         sent2 = node2.sent
-        assert sent1 == [0, 1]
-        assert sent2 == [2, 3]
+        assert sent1 == [0, 2]
+        assert sent2 == [1, 3]
         assert sched.pending == [4, 5]
         assert sched.node2pending[node1] == sent1
         assert sched.node2pending[node2] == sent2
         assert len(sched.pending) == 2
         sched.remove_item(node1, 0)
-        assert node1.sent == [0, 1, 4]
+        assert node1.sent == [0, 2, 4]
         assert sched.pending == [5]
-        assert node2.sent == [2, 3]
-        sched.remove_item(node1, 1)
-        assert node1.sent == [0, 1, 4, 5]
+        assert node2.sent == [1, 3]
+        sched.remove_item(node1, 2)
+        assert node1.sent == [0, 2, 4, 5]
+        assert not sched.pending
+
+    def test_init_distribute_fewer_tests_than_nodes(self):
+        sched = LoadScheduling(2)
+        sched.addnode(MockNode())
+        sched.addnode(MockNode())
+        sched.addnode(MockNode())
+        node1, node2, node3 = sched.nodes
+        col = ["xyz"] * 2
+        sched.addnode_collection(node1, col)
+        sched.addnode_collection(node2, col)
+        sched.init_distribute()
+        # assert not sched.tests_finished()
+        sent1 = node1.sent
+        sent2 = node2.sent
+        sent3 = node3.sent
+        assert sent1 == [0]
+        assert sent2 == [1]
+        assert sent3 == []
+        assert not sched.pending
+
+    def test_init_distribute_fewer_than_two_tests_per_node(self):
+        sched = LoadScheduling(2)
+        sched.addnode(MockNode())
+        sched.addnode(MockNode())
+        sched.addnode(MockNode())
+        node1, node2, node3 = sched.nodes
+        col = ["xyz"] * 5
+        sched.addnode_collection(node1, col)
+        sched.addnode_collection(node2, col)
+        sched.init_distribute()
+        # assert not sched.tests_finished()
+        sent1 = node1.sent
+        sent2 = node2.sent
+        sent3 = node3.sent
+        assert sent1 == [0, 3]
+        assert sent2 == [1, 4]
+        assert sent3 == [2]
         assert not sched.pending
 
     def test_add_remove_node(self):