nbs/03a_parallel.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#default_exp parallel"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "from fastcore.utils import *\n",
    "from functools import wraps\n",
    "\n",
    "from multiprocessing import Process, Queue\n",
    "import concurrent.futures,time\n",
    "from multiprocessing import Manager, set_start_method\n",
    "from threading import Thread\n",
    "try:\n",
    "    if sys.platform == 'darwin' and IN_NOTEBOOK: set_start_method(\"fork\")\n",
    "except: pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from fastcore.test import *\n",
    "from nbdev.showdoc import *\n",
    "from fastcore.nb_imports import *"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Parallel\n",
    "\n",
    "> Threading and multiprocessing functions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def threaded(f):\n",
    "    \"Run `f` in a thread, and returns the thread\"\n",
    "    @wraps(f)\n",
    "    def _f(*args, **kwargs):\n",
    "        res = Thread(target=f, args=args, kwargs=kwargs)\n",
    "        res.start()\n",
    "        return res\n",
    "    return _f"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "first\n",
      "second\n"
     ]
    }
   ],
   "source": [
    "@threaded\n",
    "def _1():\n",
    "    time.sleep(0.05)\n",
    "    print(\"second\")\n",
    "\n",
    "@threaded\n",
    "def _2():\n",
    "    time.sleep(0.01)\n",
    "    print(\"first\")\n",
    "\n",
    "_1()\n",
    "_2()\n",
    "time.sleep(0.1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def startthread(f):\n",
    "    \"Like `threaded`, but start thread immediately\"\n",
    "    threaded(f)()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "first\n",
      "second\n"
     ]
    }
   ],
   "source": [
    "@startthread\n",
    "def _():\n",
    "    time.sleep(0.05)\n",
    "    print(\"second\")\n",
    "\n",
    "@startthread\n",
    "def _():\n",
    "    time.sleep(0.01)\n",
    "    print(\"first\")\n",
    "\n",
    "time.sleep(0.1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def _call(lock, pause, n, g, item):\n",
    "    l = False\n",
    "    if pause:\n",
    "        try:\n",
    "            l = lock.acquire(timeout=pause*(n+2))\n",
    "            time.sleep(pause)\n",
    "        finally:\n",
    "            if l: lock.release()\n",
    "    return g(item)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def parallelable(param_name, num_workers, f=None):\n",
    "    f_in_main = f == None or sys.modules[f.__module__].__name__ == \"__main__\"\n",
    "    if sys.platform == \"win32\" and IN_NOTEBOOK and num_workers > 0 and f_in_main:\n",
    "        print(\"Due to IPython and Windows limitation, python multiprocessing isn't available now.\")\n",
    "        print(f\"So `{param_name}` has to be changed to 0 to avoid getting stuck\")\n",
    "        return False\n",
    "    return True"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "class ThreadPoolExecutor(concurrent.futures.ThreadPoolExecutor):\n",
    "    \"Same as Python's ThreadPoolExecutor, except can pass `max_workers==0` for serial execution\"\n",
    "    def __init__(self, max_workers=defaults.cpus, on_exc=print, pause=0, **kwargs):\n",
    "        if max_workers is None: max_workers=defaults.cpus\n",
    "        store_attr()\n",
    "        self.not_parallel = max_workers==0\n",
    "        if self.not_parallel: max_workers=1\n",
    "        super().__init__(max_workers, **kwargs)\n",
    "\n",
    "    def map(self, f, items, *args, timeout=None, chunksize=1, **kwargs):\n",
    "        if self.not_parallel == False: self.lock = Manager().Lock()\n",
    "        g = partial(f, *args, **kwargs)\n",
    "        if self.not_parallel: return map(g, items)\n",
    "        _g = partial(_call, self.lock, self.pause, self.max_workers, g)\n",
    "        try: return super().map(_g, items, timeout=timeout, chunksize=chunksize)\n",
    "        except Exception as e: self.on_exc(e)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "<h4 id=\"ThreadPoolExecutor\" class=\"doc_header\"><code>class</code> <code>ThreadPoolExecutor</code><a href=\"\" class=\"source_link\" style=\"float:right\">[source]</a></h4>\n",
       "\n",
       "> <code>ThreadPoolExecutor</code>(**`max_workers`**=*`4`*, **`on_exc`**=*`print`*, **`pause`**=*`0`*, **\\*\\*`kwargs`**) :: [`ThreadPoolExecutor`](/parallel.html#ThreadPoolExecutor)\n",
       "\n",
       "Same as Python's ThreadPoolExecutor, except can pass `max_workers==0` for serial execution"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "show_doc(ThreadPoolExecutor, title_level=4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "class ProcessPoolExecutor(concurrent.futures.ProcessPoolExecutor):\n",
    "    \"Same as Python's ProcessPoolExecutor, except can pass `max_workers==0` for serial execution\"\n",
    "    def __init__(self, max_workers=defaults.cpus, on_exc=print, pause=0, **kwargs):\n",
    "        if max_workers is None: max_workers=defaults.cpus\n",
    "        store_attr()\n",
    "        self.not_parallel = max_workers==0\n",
    "        if self.not_parallel: max_workers=1\n",
    "        super().__init__(max_workers, **kwargs)\n",
    "\n",
    "    def map(self, f, items, *args, timeout=None, chunksize=1, **kwargs):\n",
    "        if not parallelable('max_workers', self.max_workers, f): self.max_workers = 0\n",
    "        self.not_parallel = self.max_workers==0\n",
    "        if self.not_parallel: self.max_workers=1\n",
    "\n",
    "        if self.not_parallel == False: self.lock = Manager().Lock()\n",
    "        g = partial(f, *args, **kwargs)\n",
    "        if self.not_parallel: return map(g, items)\n",
    "        _g = partial(_call, self.lock, self.pause, self.max_workers, g)\n",
    "        try: return super().map(_g, items, timeout=timeout, chunksize=chunksize)\n",
    "        except Exception as e: self.on_exc(e)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "<h4 id=\"ProcessPoolExecutor\" class=\"doc_header\"><code>class</code> <code>ProcessPoolExecutor</code><a href=\"\" class=\"source_link\" style=\"float:right\">[source]</a></h4>\n",
       "\n",
       "> <code>ProcessPoolExecutor</code>(**`max_workers`**=*`4`*, **`on_exc`**=*`print`*, **`pause`**=*`0`*, **\\*\\*`kwargs`**) :: [`ProcessPoolExecutor`](/parallel.html#ProcessPoolExecutor)\n",
       "\n",
       "Same as Python's ProcessPoolExecutor, except can pass `max_workers==0` for serial execution"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "show_doc(ProcessPoolExecutor, title_level=4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "try: from fastprogress import progress_bar\n",
    "except: progress_bar = None"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def parallel(f, items, *args, n_workers=defaults.cpus, total=None, progress=None, pause=0,\n",
    "             threadpool=False, timeout=None, chunksize=1, **kwargs):\n",
    "    \"Applies `func` in parallel to `items`, using `n_workers`\"\n",
    "    pool = ThreadPoolExecutor if threadpool else ProcessPoolExecutor\n",
    "    with pool(n_workers, pause=pause) as ex:\n",
    "        r = ex.map(f,items, *args, timeout=timeout, chunksize=chunksize, **kwargs)\n",
    "        if progress and progress_bar:\n",
    "            if total is None: total = len(items)\n",
    "            r = progress_bar(r, total=total, leave=False)\n",
    "        return L(r)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def add_one(x, a=1):\n",
    "    # this import is necessary for multiprocessing in notebook on windows\n",
    "    import random\n",
    "    time.sleep(random.random()/80)\n",
    "    return x+a"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "inp,exp = range(50),range(1,51)\n",
    "\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",
    "test_eq(parallel(add_one, inp, n_workers=0), exp)\n",
    "test_eq(parallel(add_one, inp, n_workers=0, a=2), range(2,52))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Use the `pause` parameter to ensure a pause of `pause` seconds between processes starting. This is in case there are race conditions in starting some process, or to stagger the time each process starts, for example when making many requests to a webserver. Set `threadpool=True` to use `ThreadPoolExecutor` instead of `ProcessPoolExecutor`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 2022-07-01 18:00:33.687478\n",
      "1 2022-07-01 18:00:33.938175\n",
      "2 2022-07-01 18:00:34.189594\n",
      "3 2022-07-01 18:00:34.440545\n",
      "4 2022-07-01 18:00:34.691130\n"
     ]
    }
   ],
   "source": [
    "from datetime import datetime\n",
    "\n",
    "def print_time(i): \n",
    "    time.sleep(random.random()/1000)\n",
    "    print(i, datetime.now())\n",
    "\n",
    "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,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(#8) [0,2,4,6,8,10,12,14]"
      ]
     },
     "execution_count": null,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "parallel(die_sometimes, range(8))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def run_procs(f, f_done, args):\n",
    "    \"Call `f` for each item in `args` in parallel, yielding `f_done`\"\n",
    "    processes = L(args).map(Process, args=arg0, target=f)\n",
    "    for o in processes: o.start()\n",
    "    yield from f_done()\n",
    "    processes.map(Self.join())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export\n",
    "def _f_pg(obj, queue, batch, start_idx):\n",
    "    for i,b in enumerate(obj(batch)): queue.put((start_idx+i,b))\n",
    "\n",
    "def _done_pg(queue, items): return (queue.get() for _ in items)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#export \n",
    "def parallel_gen(cls, items, n_workers=defaults.cpus, **kwargs):\n",
    "    \"Instantiate `cls` in `n_workers` procs & call each on a subset of `items` in parallel.\"\n",
    "    if not parallelable('n_workers', n_workers): n_workers = 0\n",
    "    if n_workers==0:\n",
    "        yield from enumerate(list(cls(**kwargs)(items)))\n",
    "        return\n",
    "    batches = L(chunked(items, n_chunks=n_workers))\n",
    "    idx = L(itertools.accumulate(0 + batches.map(len)))\n",
    "    queue = Queue()\n",
    "    if progress_bar: items = progress_bar(items, leave=False)\n",
    "    f=partial(_f_pg, cls(**kwargs), queue)\n",
    "    done=partial(_done_pg, queue, items)\n",
    "    yield from run_procs(f, done, L(batches,idx).zip())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "\n",
       "<style>\n",
       "    /* Turns off some styling */\n",
       "    progress {\n",
       "        /* gets rid of default border in Firefox and Opera. */\n",
       "        border: none;\n",
       "        /* Needs to be in here for Safari polyfill so background images work as expected. */\n",
       "        background-size: auto;\n",
       "    }\n",
       "    .progress-bar-interrupted, .progress-bar-interrupted::-webkit-progress-bar {\n",
       "        background: #F44336;\n",
       "    }\n",
       "</style>\n"
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/html": [],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "class _C:\n",
    "    def __call__(self, o): return ((i+1) for i in o)\n",
    "\n",
    "items = range(5)\n",
    "\n",
    "res = L(parallel_gen(_C, items, n_workers=0))\n",
    "idxs,dat1 = zip(*res.sorted(itemgetter(0)))\n",
    "test_eq(dat1, range(1,6))\n",
    "\n",
    "res = L(parallel_gen(_C, items, n_workers=3))\n",
    "idxs,dat2 = zip(*res.sorted(itemgetter(0)))\n",
    "test_eq(dat2, dat1)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "`cls` is any class with `__call__`. It will be passed `args` and `kwargs` when initialized. Note that `n_workers` instances of `cls` are created, one in each process. `items` are then split in `n_workers` batches and one is sent to each `cls`. The function then returns a generator of tuples of item indices and results."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "\n",
       "<style>\n",
       "    /* Turns off some styling */\n",
       "    progress {\n",
       "        /* gets rid of default border in Firefox and Opera. */\n",
       "        border: none;\n",
       "        /* Needs to be in here for Safari polyfill so background images work as expected. */\n",
       "        background-size: auto;\n",
       "    }\n",
       "    .progress-bar-interrupted, .progress-bar-interrupted::-webkit-progress-bar {\n",
       "        background: #F44336;\n",
       "    }\n",
       "</style>\n"
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/html": [],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "class TestSleepyBatchFunc:\n",
    "    \"For testing parallel processes that run at different speeds\"\n",
    "    def __init__(self): self.a=1\n",
    "    def __call__(self, batch):\n",
    "        for k in batch:\n",
    "            time.sleep(random.random()/4)\n",
    "            yield k+self.a\n",
    "\n",
    "x = np.linspace(0,0.99,20)\n",
    "\n",
    "res = L(parallel_gen(TestSleepyBatchFunc, x, n_workers=2))\n",
    "test_eq(res.sorted().itemgot(1), x+1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#hide\n",
    "from subprocess import Popen, PIPE\n",
    "# test num_workers > 0 in scripts works when python process start method is spawn\n",
    "process = Popen([\"python\", \"parallel_test.py\"], stdout=PIPE)\n",
    "_, err = process.communicate(timeout=10)\n",
    "exit_code = process.wait()\n",
    "test_eq(exit_code, 0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Export -"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Converted 00_test.ipynb.\n",
      "Converted 01_basics.ipynb.\n",
      "Converted 02_foundation.ipynb.\n",
      "Converted 03_xtras.ipynb.\n",
      "Converted 03a_parallel.ipynb.\n",
      "Converted 03b_net.ipynb.\n",
      "Converted 04_dispatch.ipynb.\n",
      "Converted 05_transform.ipynb.\n",
      "Converted 06_docments.ipynb.\n",
      "Converted 07_meta.ipynb.\n",
      "Converted 08_script.ipynb.\n",
      "Converted index.ipynb.\n",
      "Converted parallel_win.ipynb.\n"
     ]
    }
   ],
   "source": [
    "#hide\n",
    "from nbdev.export import notebook2script\n",
    "notebook2script()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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  "jupytext": {
   "split_at_heading": true
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   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
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  "language_info": {
   "codemirror_mode": {
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   "file_extension": ".py",
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   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.9.10"
  },
  "toc": {
   "base_numbering": 1,
   "nav_menu": {},
   "number_sections": false,
   "sideBar": true,
   "skip_h1_title": false,
   "title_cell": "Table of Contents",
   "title_sidebar": "Contents",
   "toc_cell": false,
   "toc_position": {},
   "toc_section_display": true,
   "toc_window_display": false
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}