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Lazy import progress_bar #812

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Merged
jph00 merged 1 commit into from
May 9, 2026
+24 −7
Merged

Lazy import progress_bar #812

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1 change: 1 addition & 0 deletions fastcore/_modidx.py
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Original file line number Diff line number Diff line change
Expand Up @@ -582,6 +582,7 @@
'fastcore.parallel._done_pg': ('parallel.html#_done_pg', 'fastcore/parallel.py'),
'fastcore.parallel._f_pg': ('parallel.html#_f_pg', 'fastcore/parallel.py'),
'fastcore.parallel.bg_task': ('parallel.html#bg_task', 'fastcore/parallel.py'),
'fastcore.parallel.import_progress_bar': ('parallel.html#import_progress_bar', 'fastcore/parallel.py'),
'fastcore.parallel.parallel': ('parallel.html#parallel', 'fastcore/parallel.py'),
'fastcore.parallel.parallel_async': ('parallel.html#parallel_async', 'fastcore/parallel.py'),
'fastcore.parallel.parallel_gen': ('parallel.html#parallel_gen', 'fastcore/parallel.py'),
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12 changes: 8 additions & 4 deletions fastcore/parallel.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,8 @@
# AUTOGENERATED! DO NOT EDIT! File to edit: ../nbs/03a_parallel.ipynb.

# %% auto #0
__all__ = ['threaded', 'startthread', 'startproc', 'parallelable', 'ThreadPoolExecutor', 'ProcessPoolExecutor', 'parallel',
'parallel_async', 'bg_task', 'run_procs', 'parallel_gen']
__all__ = ['threaded', 'startthread', 'startproc', 'parallelable', 'ThreadPoolExecutor', 'ProcessPoolExecutor',
'import_progress_bar', 'parallel', 'parallel_async', 'bg_task', 'run_procs', 'parallel_gen']

# %% ../nbs/03a_parallel.ipynb #569d18c6
from .imports import *
Expand Down Expand Up @@ -118,13 +118,16 @@ def map(self, f, items, *args, timeout=None, chunksize=1, **kwargs):
except Exception as e: self.on_exc(e)

# %% ../nbs/03a_parallel.ipynb #f5327cb3
try: from fastprogress import progress_bar
except: progress_bar = None
def import_progress_bar():
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@jph00 jph00 May 9, 2026

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FYI I don't think this is worth having a function for - it replaces 2 simple lines of code used in 2 places, with 4 less-simple lines of code in the function plus 2 lines to call it! :)

try: from fastprogress import progress_bar
except ImportError: return None
return progress_bar

# %% ../nbs/03a_parallel.ipynb #529e1bb1
def parallel(f, items, *args, n_workers=defaults.cpus, total=None, progress=None, pause=0,
method=None, threadpool=False, timeout=None, chunksize=1, **kwargs):
"Applies `func` in parallel to `items`, using `n_workers`"
progress_bar = import_progress_bar()
kwpool = {}
if threadpool: pool = ThreadPoolExecutor
else:
Expand Down Expand Up @@ -188,6 +191,7 @@ def _done_pg(queue, items): return (queue.get() for _ in items)
# %% ../nbs/03a_parallel.ipynb #1122caee
def parallel_gen(cls, items, n_workers=defaults.cpus, progress=True, **kwargs):
"Instantiate `cls` in `n_workers` procs & call each on a subset of `items` in parallel."
progress_bar = import_progress_bar()
if not parallelable('n_workers', n_workers): n_workers = 0
if n_workers==0:
yield from enumerate(list(cls(**kwargs)(items)))
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18 changes: 15 additions & 3 deletions nbs/03a_parallel.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -460,6 +460,14 @@
"show_doc(ProcessPoolExecutor, title_level=4)"
]
},
{
"cell_type": "markdown",
"id": "b1d7c809",
"metadata": {},
"source": [
"We define `import_progress_bar` to lazily import, `fastprogress` depends on `fasthtml` and takes about 1 sec to load"
]
},
{
"cell_type": "code",
"execution_count": null,
Expand All @@ -468,8 +476,10 @@
"outputs": [],
"source": [
"#| export\n",
"try: from fastprogress import progress_bar\n",
"except: progress_bar = None"
"def import_progress_bar():\n",
" try: from fastprogress import progress_bar\n",
" except ImportError: return None\n",
" return progress_bar"
]
},
{
Expand All @@ -483,6 +493,7 @@
"def parallel(f, items, *args, n_workers=defaults.cpus, total=None, progress=None, pause=0,\n",
" method=None, threadpool=False, timeout=None, chunksize=1, **kwargs):\n",
" \"Applies `func` in parallel to `items`, using `n_workers`\"\n",
" progress_bar = import_progress_bar()\n",
" kwpool = {}\n",
" if threadpool: pool = ThreadPoolExecutor\n",
" else:\n",
Expand Down Expand Up @@ -980,9 +991,10 @@
"metadata": {},
"outputs": [],
"source": [
"#| export \n",
"#| export\n",
"def parallel_gen(cls, items, n_workers=defaults.cpus, progress=True, **kwargs):\n",
" \"Instantiate `cls` in `n_workers` procs & call each on a subset of `items` in parallel.\"\n",
" progress_bar = import_progress_bar()\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",
Expand Down
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