prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  By default use core number as n_parallel for threaded scheduling
  Use core number as `n_parallel` for threaded scheduling, currently 1 thread by default.
  
  </issue>
  <code>
  [start of mars/session.py]
  1 #!/usr/bin/env python
  2 # -*- coding: utf-8 -*-
  3 # Copyright 1999-2018 Alibaba Group Holding Ltd.
  4 #
  5 # Licensed under the Apache License, Version 2.0 (the "License");
  6 # you may not use this file except in compliance with the License.
  7 # You may obtain a copy of the License at
  8 #
  9 #      http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 
  17 import numpy as np
  18 
  19 
  20 class LocalSession(object):
  21     def __init__(self):
  22         from .tensor.execution.core import Executor
  23 
  24         self._executor = Executor()
  25         self._endpoint = None
  26 
  27     @property
  28     def endpoint(self):
  29         return self._endpoint
  30 
  31     @endpoint.setter
  32     def endpoint(self, endpoint):
  33         if endpoint is not None:
  34             raise ValueError('Local session cannot set endpoint')
  35         self._endpoint = endpoint
  36 
  37     def run(self, *tensors, **kw):
  38         if self._executor is None:
  39             raise RuntimeError('Session has closed')
  40         return self._executor.execute_tensors(tensors, **kw)
  41 
  42     def decref(self, *keys):
  43         self._executor.decref(*keys)
  44 
  45     def __enter__(self):
  46         return self
  47 
  48     def __exit__(self, *_):
  49         self._executor = None
  50 
  51 
  52 class Session(object):
  53     _default_session = None
  54 
  55     def __init__(self, endpoint=None):
  56         if endpoint is not None:
  57             if 'http' in endpoint:
  58                 # connect to web
  59                 from .web.session import Session as WebSession
  60 
  61                 self._sess = WebSession(endpoint)
  62             else:
  63                 # connect to local cluster
  64                 from .deploy.local.session import LocalClusterSession
  65 
  66                 self._sess = LocalClusterSession(endpoint)
  67         else:
  68             self._sess = LocalSession()
  69 
  70         self._executed_keys = set()
  71 
  72     def run(self, *tensors, **kw):
  73         from . import tensor as mt
  74 
  75         ret_list = False
  76         if len(tensors) == 1 and isinstance(tensors[0], (tuple, list)):
  77             ret_list = True
  78             tensors = tensors[0]
  79         elif len(tensors) > 1:
  80             ret_list = True
  81 
  82         tensors = tuple(mt.tensor(t) for t in tensors)
  83         result = self._sess.run(*tensors, **kw)
  84         self._executed_keys.update(t.key for t in tensors)
  85         for t in tensors:
  86             t._execute_session = self
  87 
  88         ret = []
  89         for r, t in zip(result, tensors):
  90             if r is None:
  91                 ret.append(r)
  92                 continue
  93             if t.isscalar() and hasattr(r, 'item'):
  94                 ret.append(np.asscalar(r))
  95             else:
  96                 ret.append(r)
  97         if ret_list:
  98             return ret
  99         return ret[0]
  100 
  101     @property
  102     def endpoint(self):
  103         return self._sess.endpoint
  104 
  105     @endpoint.setter
  106     def endpoint(self, endpoint):
  107         self._sess.endpoint = endpoint
  108 
  109     def decref(self, *keys):
  110         if hasattr(self._sess, 'decref'):
  111             self._sess.decref(*keys)
  112 
  113     def __getattr__(self, attr):
  114         try:
  115             obj = self._sess.__getattribute__(attr)
  116             return obj
  117         except AttributeError:
  118             raise
  119 
  120     def __enter__(self):
  121         self._sess.__enter__()
  122         return self
  123 
  124     def __exit__(self, exc_type, exc_val, exc_tb):
  125         self._sess.__exit__(exc_type, exc_val, exc_tb)
  126 
  127     close = __exit__
  128 
  129     def as_default(self):
  130         Session._default_session = self
  131         return self
  132 
  133     @classmethod
  134     def default_or_local(cls):
  135         if cls._default_session is not None:
  136             return cls._default_session
  137 
  138         cls._default_session = Session()
  139         return cls._default_session
  140 
  141 
  142 def new_session(scheduler=None):
  143     return Session(scheduler)
  144
  [end of mars/session.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/mars/session.py b/mars/session.py
  --- a/mars/session.py
  +++ b/mars/session.py
  @@ -16,6 +16,11 @@
   
   import numpy as np
   
  +try:
  +    from .resource import cpu_count
  +except ImportError:
  +    from multiprocessing import cpu_count
  +
   
   class LocalSession(object):
       def __init__(self):
  @@ -37,6 +42,8 @@
       def run(self, *tensors, **kw):
           if self._executor is None:
               raise RuntimeError('Session has closed')
  +        if 'n_parallel' not in kw:
  +            kw['n_parallel'] = cpu_count()
           return self._executor.execute_tensors(tensors, **kw)
   
       def decref(self, *keys):
  
verification_info: {"golden_diff": "diff --git a/mars/session.py b/mars/session.py\n--- a/mars/session.py\n+++ b/mars/session.py\n@@ -16,6 +16,11 @@\n \n import numpy as np\n \n+try:\n+    from .resource import cpu_count\n+except ImportError:\n+    from multiprocessing import cpu_count\n+\n \n class LocalSession(object):\n     def __init__(self):\n@@ -37,6 +42,8 @@\n     def run(self, *tensors, **kw):\n         if self._executor is None:\n             raise RuntimeError('Session has closed')\n+        if 'n_parallel' not in kw:\n+            kw['n_parallel'] = cpu_count()\n         return self._executor.execute_tensors(tensors, **kw)\n \n     def decref(self, *keys):\n", "issue": "By default use core number as n_parallel for threaded scheduling\nUse core number as `n_parallel` for threaded scheduling, currently 1 thread by default.\n", "before_files": [{"content": "#!/usr/bin/env python\n# -*- coding: utf-8 -*-\n# Copyright 1999-2018 Alibaba Group Holding Ltd.\n#\n# Licensed under the Apache License, Version 2.0 (the \"License\");\n# you may not use this file except in compliance with the License.\n# You may obtain a copy of the License at\n#\n#      http://www.apache.org/licenses/LICENSE-2.0\n#\n# Unless required by applicable law or agreed to in writing, software\n# distributed under the License is distributed on an \"AS IS\" BASIS,\n# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n# See the License for the specific language governing permissions and\n# limitations under the License.\n\nimport numpy as np\n\n\nclass LocalSession(object):\n    def __init__(self):\n        from .tensor.execution.core import Executor\n\n        self._executor = Executor()\n        self._endpoint = None\n\n    @property\n    def endpoint(self):\n        return self._endpoint\n\n    @endpoint.setter\n    def endpoint(self, endpoint):\n        if endpoint is not None:\n            raise ValueError('Local session cannot set endpoint')\n        self._endpoint = endpoint\n\n    def run(self, *tensors, **kw):\n        if self._executor is None:\n            raise RuntimeError('Session has closed')\n        return self._executor.execute_tensors(tensors, **kw)\n\n    def decref(self, *keys):\n        self._executor.decref(*keys)\n\n    def __enter__(self):\n        return self\n\n    def __exit__(self, *_):\n        self._executor = None\n\n\nclass Session(object):\n    _default_session = None\n\n    def __init__(self, endpoint=None):\n        if endpoint is not None:\n            if 'http' in endpoint:\n                # connect to web\n                from .web.session import Session as WebSession\n\n                self._sess = WebSession(endpoint)\n            else:\n                # connect to local cluster\n                from .deploy.local.session import LocalClusterSession\n\n                self._sess = LocalClusterSession(endpoint)\n        else:\n            self._sess = LocalSession()\n\n        self._executed_keys = set()\n\n    def run(self, *tensors, **kw):\n        from . import tensor as mt\n\n        ret_list = False\n        if len(tensors) == 1 and isinstance(tensors[0], (tuple, list)):\n            ret_list = True\n            tensors = tensors[0]\n        elif len(tensors) > 1:\n            ret_list = True\n\n        tensors = tuple(mt.tensor(t) for t in tensors)\n        result = self._sess.run(*tensors, **kw)\n        self._executed_keys.update(t.key for t in tensors)\n        for t in tensors:\n            t._execute_session = self\n\n        ret = []\n        for r, t in zip(result, tensors):\n            if r is None:\n                ret.append(r)\n                continue\n            if t.isscalar() and hasattr(r, 'item'):\n                ret.append(np.asscalar(r))\n            else:\n                ret.append(r)\n        if ret_list:\n            return ret\n        return ret[0]\n\n    @property\n    def endpoint(self):\n        return self._sess.endpoint\n\n    @endpoint.setter\n    def endpoint(self, endpoint):\n        self._sess.endpoint = endpoint\n\n    def decref(self, *keys):\n        if hasattr(self._sess, 'decref'):\n            self._sess.decref(*keys)\n\n    def __getattr__(self, attr):\n        try:\n            obj = self._sess.__getattribute__(attr)\n            return obj\n        except AttributeError:\n            raise\n\n    def __enter__(self):\n        self._sess.__enter__()\n        return self\n\n    def __exit__(self, exc_type, exc_val, exc_tb):\n        self._sess.__exit__(exc_type, exc_val, exc_tb)\n\n    close = __exit__\n\n    def as_default(self):\n        Session._default_session = self\n        return self\n\n    @classmethod\n    def default_or_local(cls):\n        if cls._default_session is not None:\n            return cls._default_session\n\n        cls._default_session = Session()\n        return cls._default_session\n\n\ndef new_session(scheduler=None):\n    return Session(scheduler)\n", "path": "mars/session.py"}]}