Feat: Default to no multiprocessing.

Because multiprocessing is not open for public use, unless one really
wants to use it.  The test are incredibly coupled, so they needed some
massaging too.

Closes #314.

.travis.yml

@@ -18,8 +18,8 @@ install:
     - python setup.py develop
 # command to run tests
 script: 
-    - python  qcodes/test.py --skip-coverage
-    - python  qcodes/test.py --mp-spawn
+    - python  qcodes/test.py --skip-coverage -f
+    - python  qcodes/test.py --mp-spawn -f
 after_success:
     # install codacy coverage plugin only on traivs
     - pip install codacy-coverage

docs/examples/Tutorial.ipynb

@@ -475,10 +475,10 @@
     "# If you leave these out, you get a new timestamped DataSet each time.\n",
     "\n",
     "loop = qc.Loop(c0.sweep(0,20,0.1), delay=0.001).each(meter.amplitude)\n",
-    "data = loop.get_data_set(data_manager=False)\n",
+    "data = loop.get_data_set()\n",
     "plot = qc.QtPlot()\n",
     "plot.add(data.meter_amplitude)\n",
-    "_ = loop.with_bg_task(plot.update, 0.0005).run(name='testsweep',background=False)"
+    "_ = loop.with_bg_task(plot.update, 0.0005).run(name='testsweep')"
    ]
   },
   {
@@ -1386,7 +1386,7 @@
     "    meter.amplitude, # second measurement, at c2=1 -> amplitude_4 bcs it's action 4\n",
     "    qc.Task(c2.set, 0)\n",
     "    )\n",
-    "data = loop.get_data_set(data_manager=False)"
+    "data = loop.get_data_set()"
    ]
   },
   {
@@ -2199,7 +2199,7 @@
    "source": [
     "plot = qc.MatPlot(data.meter_amplitude_0, cmap=plt.cm.hot, figsize=(12, 4.5), subplots=(1, 2))\n",
     "plot.add(data.meter_amplitude_3, cmap=plt.cm.hot, subplot=2)\n",
-    "data2 = loop.with_bg_task(plot.update, 0.0005).run(name='2D_test',background=False)"
+    "data2 = loop.with_bg_task(plot.update, 0.0005).run(name='2D_test')"
    ]
   },
   {
@@ -2240,12 +2240,12 @@
     "    meter.amplitude, # second measurement, at c2=1 -> amplitude_4 bcs it's action 4\n",
     "    qc.Task(c2.set, 0)\n",
     "    )\n",
-    "data = loop.get_data_set(data_manager=False)\n",
+    "data = loop.get_data_set()\n",
     "\n",
     "plotQ = qc.QtPlot()\n",
     "plotQ.add(data.meter_amplitude_0, figsize=(1200, 500))\n",
     "plotQ.add(data.meter_amplitude_3, subplot=2)\n",
-    "data2 = loop.with_bg_task(plotQ.update, 0.0005).run(name='2D_test',background=False)"
+    "data2 = loop.with_bg_task(plotQ.update, 0.0005).run(name='2D_test')"
    ]
   },
   {
@@ -2275,7 +2275,7 @@
     "    qc.Loop(c2[-10:10:0.2], 0.001).each(meter.amplitude),\n",
     "    AverageGetter(meter.amplitude, c2[-10:10:0.2], 0.001)\n",
     ")\n",
-    "data = loop3.get_data_set(data_manager=False) \n"
+    "data = loop3.get_data_set() "
    ]
   },
   {
@@ -2324,7 +2324,7 @@
     "plotQ.add(data.meter_amplitude_3_0)\n",
     "plotQ.add(data.meter_amplitude_5_0, cmap='viridis', subplot=2)\n",
     "plotQ.add(data.meter_avg_amplitude, subplot=3)\n",
-    "data = loop3.with_bg_task(plotQ.update, 0.0005).run(name='TwoD_different_inner_test', background=False)"
+    "data = loop3.with_bg_task(plotQ.update, 0.0005).run(name='TwoD_different_inner_test')"
    ]
   },
   {
@@ -2365,11 +2365,11 @@
     "loop4 = qc.Loop(c1[-15:15:1], 0.01).each(\n",
     "    AverageAndRaw(meter.amplitude, c2[-10:10:0.2], 0.001)\n",
     ")\n",
-    "data4 = loop4.get_data_set(data_manager=False)\n",
+    "data4 = loop4.get_data_set()\n",
     "plotQ = qc.QtPlot()\n",
     "plotQ.add(data4.meter_amplitude, figsize=(1200, 500), cmap='viridis')\n",
     "plotQ.add(data4.meter_avg_amplitude, subplot=2)\n",
-    "data4 = loop4.with_bg_task(plotQ.update, 0.005).run(name='TwoD_average_test', background=False)"
+    "data4 = loop4.with_bg_task(plotQ.update, 0.005).run(name='TwoD_average_test')"
    ]
   }
  ],
@@ -2391,10 +2391,6 @@
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
    "version": "3.5.2"
-  },
-  "widgets": {
-   "state": {},
-   "version": "1.1.1"
   }
  },
  "nbformat": 4,

qcodes/data/data_set.py

@@ -27,7 +27,9 @@ class DataMode(Enum):
 
 
 def new_data(location=None, loc_record=None, name=None, overwrite=False,
-             io=None, data_manager=None, mode=DataMode.LOCAL, **kwargs):
+             io=None, data_manager=False, mode=DataMode.LOCAL, **kwargs):
+    # NOTE(giulioungaretti): leave this docstrings as it is, because
+    # documenting the types is silly in this case.
     """
     Create a new DataSet.
 
@@ -57,11 +59,11 @@ def new_data(location=None, loc_record=None, name=None, overwrite=False,
             says the root data directory is the current working directory, ie
             where you started the python session.
 
-        data_manager (DataManager or False, optional): manager for the
-            ``DataServer`` that offloads storage and syncing of this
-            ``DataSet``. Usually omitted (default None) to use the default
-            from ``get_data_manager()``. If ``False``, this ``DataSet`` will
-            store itself.
+        data_manager (Optional[bool]): use a manager for the
+            ``DataServer`` that offloads storage and syncing of this Defaults
+            to  ``False`` i.e. this ``DataSet`` will store itself without extra
+            processes. Set to ``True`` to use the default from
+            ``get_data_manager()``.
 
         mode (DataMode, optional): connection type to the ``DataServer``.
             ``DataMode.LOCAL``: this DataSet doesn't communicate across
@@ -105,11 +107,11 @@ def new_data(location=None, loc_record=None, name=None, overwrite=False,
     if location and (not overwrite) and io.list(location):
         raise FileExistsError('"' + location + '" already has data')
 
-    if data_manager is False:
+    if data_manager is True:
+        data_manager = get_data_manager()
+    else:
         if mode != DataMode.LOCAL:
             raise ValueError('DataSets without a data_manager must be local')
-    elif data_manager is None:
-        data_manager = get_data_manager()
 
     return DataSet(location=location, io=io, data_manager=data_manager,
                    mode=mode, **kwargs)
@@ -206,11 +208,11 @@ class DataSet(DelegateAttributes):
             says the root data directory is the current working directory, ie
             where you started the python session.
 
-        data_manager (DataManager or False, optional): manager for the
-            ``DataServer`` that offloads storage and syncing of this
-            ``DataSet``. Usually omitted (default None) to use the default
-            from ``get_data_manager()``. If ``False``, this ``DataSet`` will
-            store itself.
+        data_manager (Optional[bool]): use a manager for the
+            ``DataServer`` that offloads storage and syncing of this Defaults
+            to  ``False`` i.e. this ``DataSet`` will store itself without extra
+            processes.  Set to ``True`` to use the default from
+            ``get_data_manager()``.
 
         mode (DataMode, optional): connection type to the ``DataServer``.
             ``DataMode.LOCAL``: this DataSet doesn't communicate across
@@ -258,7 +260,7 @@ class DataSet(DelegateAttributes):
     background_functions = OrderedDict()
 
     def __init__(self, location=None, mode=DataMode.LOCAL, arrays=None,
-                 data_manager=None, formatter=None, io=None, write_period=5):
+                 data_manager=False, formatter=None, io=None, write_period=5):
         if location is False or isinstance(location, str):
             self.location = location
         else:
@@ -281,7 +283,7 @@ def __init__(self, location=None, mode=DataMode.LOCAL, arrays=None,
             for array in arrays:
                 self.add_array(array)
 
-        if data_manager is None and mode in SERVER_MODES:
+        if data_manager is True and mode in SERVER_MODES:
             data_manager = get_data_manager()
 
         if mode == DataMode.LOCAL:

qcodes/instrument/base.py

@@ -1,7 +1,8 @@
 """Instrument base class."""
-import weakref
-import time
 import logging
+import time
+import warnings
+import weakref
 
 from qcodes.utils.metadata import Metadatable
 from qcodes.utils.helpers import DelegateAttributes, strip_attrs, full_class
@@ -75,11 +76,12 @@ class Instrument(Metadatable, DelegateAttributes, NestedAttrAccess):
 
     _all_instruments = {}
 
-    def __new__(cls, *args, server_name='', **kwargs):
+    def __new__(cls, *args, server_name=None, **kwargs):
         """Figure out whether to create a base instrument or proxy."""
         if server_name is None:
             return super().__new__(cls)
         else:
+            warnings.warn("Multiprocessing is in beta, use at own risk", UserWarning)
             return RemoteInstrument(*args, instrument_class=cls,
                                     server_name=server_name, **kwargs)
 

qcodes/instrument/remote.py

@@ -43,7 +43,6 @@ class RemoteInstrument(DelegateAttributes):
 
     def __init__(self, *args, instrument_class=None, server_name='',
                  **kwargs):
-
         if server_name == '':
             server_name = instrument_class.default_server_name(**kwargs)
 

qcodes/loops.py

@@ -50,6 +50,7 @@
 import multiprocessing as mp
 import time
 import numpy as np
+import warnings
 
 from qcodes.station import Station
 from qcodes.data.data_set import new_data, DataMode
@@ -62,7 +63,10 @@
 from .actions import (_actions_snapshot, Task, Wait, _Measure, _Nest,
                       BreakIf, _QcodesBreak)
 
+# Switches off multiprocessing by default, cant' be altered after module import.
+# TODO(giulioungaretti) use config.
 
+USE_MP = False
 MP_NAME = 'Measurement'
 
 
@@ -640,7 +644,7 @@ def _check_signal(self):
             else:
                 raise ValueError('unknown signal', signal_)
 
-    def get_data_set(self, data_manager=None, *args, **kwargs):
+    def get_data_set(self, data_manager=False, *args, **kwargs):
         """
         Return the data set for this loop.
         If no data set has been created yet, a new one will be created and returned.
@@ -670,6 +674,7 @@ def get_data_set(self, data_manager=None, *args, **kwargs):
             if data_manager is False:
                 data_mode = DataMode.LOCAL
             else:
+                warnings.warn("Multiprocessing is in beta, use at own risk", UserWarning)
                 data_mode = DataMode.PUSH_TO_SERVER
 
             data_set = new_data(arrays=self.containers(), mode=data_mode,
@@ -688,20 +693,19 @@ def run_temp(self, **kwargs):
         return self.run(background=False, quiet=True,
                         data_manager=False, location=False, **kwargs)
 
-    def run(self, background=True, use_threads=True, quiet=False,
-            data_manager=None, station=None, progress_interval=False,
+    def run(self, background=USE_MP, use_threads=False, quiet=False,
+            data_manager=USE_MP, station=None, progress_interval=False,
             *args, **kwargs):
         """
         Execute this loop.
 
-        background: (default True) run this sweep in a separate process
+        background: (default False) run this sweep in a separate process
             so we can have live plotting and other analysis in the main process
         use_threads: (default True): whenever there are multiple `get` calls
             back-to-back, execute them in separate threads so they run in
             parallel (as long as they don't block each other)
         quiet: (default False): set True to not print anything except errors
-        data_manager: a DataManager instance (omit to use default,
-            False to store locally)
+        data_manager: set to True to use a DataManager. Default to False.
         station: a Station instance for snapshots (omit to use a previously
             provided Station, or the default Station)
         progress_interval (default None): show progress of the loop every x
@@ -737,6 +741,7 @@ def run(self, background=True, use_threads=True, quiet=False,
             prev_loop.join()
 
         data_set = self.get_data_set(data_manager, *args, **kwargs)
+
         self.set_common_attrs(data_set=data_set, use_threads=use_threads,
                               signal_queue=self.signal_queue)
 
@@ -762,6 +767,7 @@ def run(self, background=True, use_threads=True, quiet=False,
                   flush=True)
 
         if background:
+            warnings.warn("Multiprocessing is in beta, use at own risk", UserWarning)
             p = QcodesProcess(target=self._run_wrapper, name=MP_NAME)
             p.is_sweep = True
             p.signal_queue = self.signal_queue

qcodes/process/helpers.py

@@ -2,6 +2,7 @@
 
 import multiprocessing as mp
 import time
+import warnings
 
 MP_ERR = 'context has already been set'
 
@@ -23,6 +24,7 @@ def set_mp_method(method, force=False):
         with the *same* method raises an error, but here we only
         raise the error if you *don't* force *and* the context changes
     """
+    warnings.warn("Multiprocessing is in beta, use at own risk", UserWarning)
     try:
         mp.set_start_method(method, force=force)
     except RuntimeError as err:

qcodes/process/stream_queue.py

@@ -2,9 +2,10 @@
 
 import multiprocessing as mp
 import sys
-from datetime import datetime
 import time
 
+from datetime import datetime
+
 from .helpers import kill_queue
 
 

qcodes/tests/test_data.py

@@ -449,14 +449,14 @@ def test_from_server(self, gdm_mock):
         mock_dm.live_data = MockLive()
 
         # wrong location or False location - converts to local
-        data = DataSet(location='Jupiter', mode=DataMode.PULL_FROM_SERVER)
+        data = DataSet(location='Jupiter', data_manager=True, mode=DataMode.PULL_FROM_SERVER)
         self.assertEqual(data.mode, DataMode.LOCAL)
 
-        data = DataSet(location=False, mode=DataMode.PULL_FROM_SERVER)
+        data = DataSet(location=False,  data_manager=True, mode=DataMode.PULL_FROM_SERVER)
         self.assertEqual(data.mode, DataMode.LOCAL)
 
         # location matching server - stays in server mode
-        data = DataSet(location='Mars', mode=DataMode.PULL_FROM_SERVER,
+        data = DataSet(location='Mars',  data_manager=True, mode=DataMode.PULL_FROM_SERVER,
                        formatter=MockFormatter())
         self.assertEqual(data.mode, DataMode.PULL_FROM_SERVER)
         self.assertEqual(data.arrays, MockLive.arrays)
@@ -495,7 +495,7 @@ def test_to_server(self, gdm_mock):
         mock_dm.needs_restart = True
         gdm_mock.return_value = mock_dm
 
-        data = DataSet(location='Venus', mode=DataMode.PUSH_TO_SERVER)
+        data = DataSet(location='Venus', data_manager=True, mode=DataMode.PUSH_TO_SERVER)
         self.assertEqual(mock_dm.needs_restart, False, data)
         self.assertEqual(mock_dm.data_set, data)
         self.assertEqual(data.data_manager, mock_dm)

qcodes/tests/test_driver_testcase.py

@@ -34,7 +34,7 @@ class TestDriverTestCase(DriverTestCase):
     @classmethod
     def setUpClass(cls):
         cls.an_empty_model = EmptyModel()
-        cls.an_instrument = MockMock('a', model=cls.an_empty_model)
+        cls.an_instrument = MockMock('a', model=cls.an_empty_model, server_name='')
         super().setUpClass()
 
     @classmethod

qcodes/tests/test_instrument.py

@@ -31,6 +31,7 @@ def __init__(self, *args, **kwargs):
                            vals=Numbers(-10, 10), step=0.2,
                            delay=0.01,
                            max_delay='forever')
+        self.crahs()
 
 
 class GatesBadDelayValue(MockGates):
@@ -51,9 +52,9 @@ class TestInstrument(TestCase):
     def setUpClass(cls):
         cls.model = AMockModel()
 
-        cls.gates = MockGates(model=cls.model)
-        cls.source = MockSource(model=cls.model)
-        cls.meter = MockMeter(model=cls.model, keep_history=False)
+        cls.gates = MockGates(model=cls.model, server_name='')
+        cls.source = MockSource(model=cls.model, server_name='')
+        cls.meter = MockMeter(model=cls.model, keep_history=False, server_name='')
 
     def setUp(self):
         # reset the model state via the gates function
@@ -192,7 +193,7 @@ def test_remove_instance(self):
         with self.assertRaises(KeyError):
             Instrument.find_instrument('gates')
 
-        type(self).gates = MockGates(model=self.model)
+        type(self).gates = MockGates(model=self.model, server_name="")
         self.assertEqual(self.gates.instances(), [self.gates])
         self.assertEqual(Instrument.find_instrument('gates'), self.gates)
 
@@ -941,7 +942,7 @@ def setUp(self):
             name='testdummy', gates=['dac1', 'dac2', 'dac3'], server_name=None)
 
     def tearDown(self):
-        #TODO (giulioungaretti) remove ( does nothing ?)
+        # TODO (giulioungaretti) remove ( does nothing ?)
         pass
 
     def test_attr_access(self):