diff --git a/daliuge-engine/test/manager/test_dm.py b/daliuge-engine/test/manager/test_dm.py
index 835ff8d6a..ed5e76c8d 100644
--- a/daliuge-engine/test/manager/test_dm.py
+++ b/daliuge-engine/test/manager/test_dm.py
@@ -151,7 +151,7 @@ def _test_runGraphInTwoNMs(
         return leaf_drop_data
 
 
-class TestDMParallel(NMTestsMixIn, unittest.TestCase):
+class TestDM(NMTestsMixIn, unittest.TestCase):
     def _deploy_error_graph(self, **kwargs):
         sessionId = f"s{random.randint(0, 1000)}"
         g = [
@@ -164,7 +164,7 @@ def _deploy_error_graph(self, **kwargs):
             },
             {"oid": "C", "type": "plain", "storage": Categories.MEMORY, "producers": ["B"]},
         ]
-        dm = self._start_dm(threads=multiprocessing.cpu_count(), **kwargs)
+        dm = self._start_dm(**kwargs)
         dm.createSession(sessionId)
         dm.addGraphSpec(sessionId, g)
         dm.deploySession(sessionId, ["A"])
@@ -209,8 +209,7 @@ def _test_runGraphOneDOPerDOM(self, repeats=1):
         rels = [DROPRel("B", DROPLinkType.CONSUMER, "A")]
         a_data = os.urandom(32)
         c_data = str(crc32(a_data, 0)).encode('utf8')
-        node_managers = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
-
+        node_managers = [self._start_dm() for _ in range(2)]
         ids = [0] * repeats
         for n in range(repeats):
             choice = 0
@@ -254,9 +253,9 @@ def test_runGraphSeveralDropsPerDM(self):
 
         :see: `self.test_runGraphSingleDOPerDOM`
         """
-        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
+        dm1, dm2 = [self._start_dm() for _ in range(2)]
 
-        sessionId = f"s{random.randint(0, 1000)}"
+        sessionId = "s1"
         g1 = [
             {"oid": "A", "type": "plain", "storage": Categories.MEMORY, "consumers": ["C"]},
             {"oid": "B", "type": "plain", "storage": Categories.MEMORY},
@@ -325,7 +324,7 @@ def test_runWithFourDMs(self):
         B, F, G, K and N are AppDOs; the rest are plain in-memory DROPs
         """
 
-        dm1, dm2, dm3, dm4 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(4)]
+        dm1, dm2, dm3, dm4 = [self._start_dm() for _ in range(4)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         g1 = [memory("A", expectedSize=1)]
@@ -411,7 +410,7 @@ def test_many_relationships(self):
         =======    ====================
         """
 
-        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
+        dm1, dm2 = [self._start_dm() for _ in range(2)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         N = 100
@@ -469,7 +468,7 @@ def test_runGraphSeveralDropsPerDM_with_get_consumer_nodes(self):
         ip_addr_1 = "8.8.8.8"
         ip_addr_2 = "8.8.8.9"
 
-        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()//2) for _ in range(2)]
+        dm1, dm2 = [self._start_dm() for _ in range(2)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         g1 = [
@@ -585,7 +584,7 @@ def test_run_streaming_consumer_remotely2(self):
         self._test_runGraphInTwoNMs(g1, g2, rels, a_data, e_data, leaf_oid="E")
 
 
-class TestDM(NMTestsMixIn, unittest.TestCase):
+class TestDMParallel(NMTestsMixIn, unittest.TestCase):
     def _deploy_error_graph(self, **kwargs):
         sessionId = f"s{random.randint(0, 1000)}"
         g = [
@@ -598,7 +597,7 @@ def _deploy_error_graph(self, **kwargs):
             },
             {"oid": "C", "type": "plain", "storage": Categories.MEMORY, "producers": ["B"]},
         ]
-        dm = self._start_dm(**kwargs)
+        dm = self._start_dm(threads=multiprocessing.cpu_count(), **kwargs)
         dm.createSession(sessionId)
         dm.addGraphSpec(sessionId, g)
         dm.deploySession(sessionId, ["A"])
@@ -643,7 +642,8 @@ def _test_runGraphOneDOPerDOM(self, repeats=1):
         rels = [DROPRel("B", DROPLinkType.CONSUMER, "A")]
         a_data = os.urandom(32)
         c_data = str(crc32(a_data, 0)).encode('utf8')
-        node_managers = [self._start_dm() for _ in range(2)]
+        node_managers = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
+
         ids = [0] * repeats
         for n in range(repeats):
             choice = 0
@@ -687,9 +687,9 @@ def test_runGraphSeveralDropsPerDM(self):
 
         :see: `self.test_runGraphSingleDOPerDOM`
         """
-        dm1, dm2 = [self._start_dm() for _ in range(2)]
+        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
 
-        sessionId = "s1"
+        sessionId = f"s{random.randint(0, 1000)}"
         g1 = [
             {"oid": "A", "type": "plain", "storage": Categories.MEMORY, "consumers": ["C"]},
             {"oid": "B", "type": "plain", "storage": Categories.MEMORY},
@@ -758,7 +758,7 @@ def test_runWithFourDMs(self):
         B, F, G, K and N are AppDOs; the rest are plain in-memory DROPs
         """
 
-        dm1, dm2, dm3, dm4 = [self._start_dm() for _ in range(4)]
+        dm1, dm2, dm3, dm4 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(4)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         g1 = [memory("A", expectedSize=1)]
@@ -844,7 +844,7 @@ def test_many_relationships(self):
         =======    ====================
         """
 
-        dm1, dm2 = [self._start_dm() for _ in range(2)]
+        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()) for _ in range(2)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         N = 100
@@ -902,7 +902,7 @@ def test_runGraphSeveralDropsPerDM_with_get_consumer_nodes(self):
         ip_addr_1 = "8.8.8.8"
         ip_addr_2 = "8.8.8.9"
 
-        dm1, dm2 = [self._start_dm() for _ in range(2)]
+        dm1, dm2 = [self._start_dm(threads=multiprocessing.cpu_count()//2) for _ in range(2)]
 
         sessionId = f"s{random.randint(0, 1000)}"
         g1 = [