use spawn on macos when not in a notebook

Author: jph00

fastcore/parallel.py

@@ -106,7 +106,7 @@ def parallel(f, items, *args, n_workers=defaults.cpus, total=None, progress=None
     kwpool = {}
     if threadpool: pool = ThreadPoolExecutor
     else:
-        if not method and sys.platform == 'darwin': method='fork'
+        if not method and sys.platform == 'darwin' and not IN_NOTEBOOK: method='spawn'
         if method: kwpool['mp_context'] = get_context(method)
         pool = ProcessPoolExecutor
     with pool(n_workers, pause=pause, **kwpool) as ex:
@@ -123,21 +123,21 @@ def add_one(x, a=1):
     time.sleep(random.random()/80)
     return x+a
 
-# %% ../nbs/03a_parallel.ipynb 22
+# %% ../nbs/03a_parallel.ipynb 21
 def run_procs(f, f_done, args):
     "Call `f` for each item in `args` in parallel, yielding `f_done`"
     processes = L(args).map(Process, args=arg0, target=f)
     for o in processes: o.start()
     yield from f_done()
     processes.map(Self.join())
 
-# %% ../nbs/03a_parallel.ipynb 23
+# %% ../nbs/03a_parallel.ipynb 22
 def _f_pg(obj, queue, batch, start_idx):
     for i,b in enumerate(obj(batch)): queue.put((start_idx+i,b))
 
 def _done_pg(queue, items): return (queue.get() for _ in items)
 
-# %% ../nbs/03a_parallel.ipynb 24
+# %% ../nbs/03a_parallel.ipynb 23
 def parallel_gen(cls, items, n_workers=defaults.cpus, **kwargs):
     "Instantiate `cls` in `n_workers` procs & call each on a subset of `items` in parallel."
     if not parallelable('n_workers', n_workers): n_workers = 0

nbs/03a_parallel.ipynb

@@ -215,7 +215,7 @@
        "Same as Python's ThreadPoolExecutor, except can pass `max_workers==0` for serial execution"
       ],
       "text/plain": [
-       "<nbdev.showdoc.BasicMarkdownRenderer at 0x1034390a0>"
+       "<nbdev.showdoc.BasicMarkdownRenderer>"
       ]
      },
      "execution_count": null,
@@ -276,7 +276,7 @@
        "Same as Python's ProcessPoolExecutor, except can pass `max_workers==0` for serial execution"
       ],
       "text/plain": [
-       "<nbdev.showdoc.BasicMarkdownRenderer at 0x10f325e20>"
+       "<nbdev.showdoc.BasicMarkdownRenderer>"
       ]
      },
      "execution_count": null,
@@ -312,7 +312,7 @@
     "    kwpool = {}\n",
     "    if threadpool: pool = ThreadPoolExecutor\n",
     "    else:\n",
-    "        if not method and sys.platform == 'darwin': method='fork'\n",
+    "        if not method and sys.platform == 'darwin' and not IN_NOTEBOOK: method='spawn'\n",
     "        if method: kwpool['mp_context'] = get_context(method)\n",
     "        pool = ProcessPoolExecutor\n",
     "    with pool(n_workers, pause=pause, **kwpool) as ex:\n",
@@ -345,7 +345,6 @@
    "source": [
     "inp,exp = range(50),range(1,51)\n",
     "\n",
-    "# test_eq(parallel(add_one, inp, method='spawn', n_workers=2, progress=False), exp)\n",
     "test_eq(parallel(add_one, inp, n_workers=2, progress=False), exp)\n",
     "test_eq(parallel(add_one, inp, threadpool=True, n_workers=2, progress=False), exp)\n",
     "test_eq(parallel(add_one, inp, n_workers=1, a=2), range(2,52))\n",
@@ -369,11 +368,11 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "0 2022-07-26 04:12:18.858918\n",
-      "1 2022-07-26 04:12:19.110316\n",
-      "2 2022-07-26 04:12:19.362060\n",
-      "3 2022-07-26 04:12:19.612606\n",
-      "4 2022-07-26 04:12:19.863821\n"
+      "0 2022-08-07 05:10:05.999916\n",
+      "1 2022-08-07 05:10:06.252031\n",
+      "2 2022-08-07 05:10:06.503603\n",
+      "3 2022-08-07 05:10:06.755216\n",
+      "4 2022-08-07 05:10:07.006702\n"
      ]
     }
    ],
@@ -387,17 +386,6 @@
     "parallel(print_time, range(5), n_workers=2, pause=0.25);"
    ]
   },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "def die_sometimes(x):\n",
-    "#     if 3<x<6: raise Exception(f\"exc: {x}\")\n",
-    "    return x*2"
-   ]
-  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -415,6 +403,11 @@
     }
    ],
    "source": [
+    "#|hide\n",
+    "def die_sometimes(x):\n",
+    "#     if 3<x<6: raise Exception(f\"exc: {x}\")\n",
+    "    return x*2\n",
+    "\n",
     "parallel(die_sometimes, range(8))"
    ]
   },
@@ -582,7 +575,6 @@
    "outputs": [],
    "source": [
     "#|hide\n",
-    "#|eval: false\n",
     "from nbdev import nbdev_export\n",
     "nbdev_export()"
    ]